Nat Plants , IF:13.256 , 2020 Jun , V6 (6) : P686-698 doi: 10.1038/s41477-020-0666-7
Robust organ size requires robust timing of initiation orchestrated by focused auxin and cytokinin signalling.
Weill Institute for Cell and Molecular Biology and School of Integrative Plant Science, Section of Plant Biology, Cornell University, Ithaca, NY, USA.; Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education, College of Horticulture and Landscape Architecture, Southwest University, Beibei, China.; Academy of Agricultural Sciences of Southwest University, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Beibei, China.; Laboratoire de Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, INRIA, Lyon, France.; Lycee Auguste et Louis Lumiere, Lyon, France.; Institute of Nuclear Agricultural Sciences, Key Laboratory of Nuclear Agricultural Sciences of Ministry of Agriculture and Zhejiang Province, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, China.; Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, Cologne, Germany.; Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.; Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan.; John Innes Centre, Norwich, UK.; Department of Mathematics, Stockholm University, Stockholm, Sweden.; Laboratoire de Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, INRIA, Lyon, France. arezki.boudaoud@ens-lyon.fr.; Weill Institute for Cell and Molecular Biology and School of Integrative Plant Science, Section of Plant Biology, Cornell University, Ithaca, NY, USA. ahr75@cornell.edu.
Organ size and shape are precisely regulated to ensure proper function. The four sepals in each Arabidopsis thaliana flower must maintain the same size throughout their growth to continuously enclose and protect the developing bud. Here we show that DEVELOPMENT RELATED MYB-LIKE 1 (DRMY1) is required for both timing of organ initiation and proper growth, leading to robust sepal size in Arabidopsis. Within each drmy1 flower, the initiation of some sepals is variably delayed. Late-initiating sepals in drmy1 mutants remain smaller throughout development, resulting in variability in sepal size. DRMY1 focuses the spatiotemporal signalling patterns of the plant hormones auxin and cytokinin, which jointly control the timing of sepal initiation. Our findings demonstrate that timing of organ initiation, together with growth and maturation, contribute to robust organ size.
PMID: 32451448
Nat Plants , IF:13.256 , 2020 Jun , V6 (6) : P699-707 doi: 10.1038/s41477-020-0661-z
Auxin export from proximal fruits drives arrest in temporally competent inflorescences.
School of Biosciences, University of Nottingham, Loughborough, UK.; School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK.; Department of Forest Genetics and Plant Physiology, Umea Plant Science Centre, Swedish University of Agricultural Sciences, Umea, Sweden.; School of Biosciences, University of Nottingham, Loughborough, UK. zoe.wilson@nottingham.ac.uk.; School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK. t.a.bennett@leeds.ac.uk.
A well-defined set of regulatory pathways control entry into the reproductive phase in flowering plants, but little is known about the mechanistic control of the end-of-flowering despite this being a critical process for optimization of fruit and seed production. Complete fruit removal, or lack of fertile fruit-set, prevents timely inflorescence arrest in Arabidopsis, leading to a previous proposal that a cumulative fruit/seed-derived signal causes simultaneous 'global proliferative arrest'. Recent studies have suggested that inflorescence arrest involves gene expression changes in the inflorescence meristem that are, at least in part, controlled by the FRUITFULL-APETALA2 pathway; however, there is limited understanding of how this process is coordinated at the whole-plant level. Here, we provide a framework for the communication previously inferred in the global proliferative arrest model. We show that the end-of-flowering in Arabidopsis is not 'global' and does not occur synchronously between branches, but rather that the arrest of each inflorescence is a local process, driven by auxin export from fruit proximal to the inflorescence apex. Furthermore, we show that inflorescences are competent for arrest only once they reach a certain developmental age. Understanding the regulation of inflorescence arrest will be of major importance to extending and maximizing crop yields.
PMID: 32451444
Nat Commun , IF:12.121 , 2020 Jun , V11 (1) : P2965 doi: 10.1038/s41467-020-16803-7
Local auxin competition explains fragmented differentiation patterns.
Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland.; Department of Plant Molecular Biology, University of Lausanne, Biophore Building, CH-1015, Lausanne, Switzerland. christian.hardtke@unil.ch.; Theoretical Biology, Department of Biology, Utrecht University, 3584 CH, Utrecht, The Netherlands. K.H.W.J.tenTusscher@uu.nl.
Trajectories of cellular ontogeny are tightly controlled and often involve feedback-regulated molecular antagonism. For example, sieve element differentiation along developing protophloem cell files of Arabidopsis roots requires two antagonistic regulators of auxin efflux. Paradoxically, loss-of-function in either regulator triggers similar, seemingly stochastic differentiation failures of individual sieve element precursors. Here we show that these patterning defects are distinct and non-random. They can be explained by auxin-dependent bistability that emerges from competition for auxin between neighboring cells. This bistability depends on the presence of an auxin influx facilitator, and can be triggered by either flux enhancement or repression. Our results uncover a hitherto overlooked aspect of auxin uptake, and highlight the contributions of local auxin influx, efflux and biosynthesis to protophloem formation. Moreover, the combined experimental-modeling approach suggests that without auxin efflux homeostasis, auxin influx interferes with coordinated differentiation.
PMID: 32528082
Plant Cell , IF:9.618 , 2020 Jun doi: 10.1105/tpc.19.00428
A CEP Peptide Receptor-like Kinase Regulates Auxin Biosynthesis and Ethylene Signaling to Coordinate Root Growth and Symbiotic Nodulation in Medicago truncatula.
State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University CITY: Beijing China [CN].; China Agricultural University, Beijing, China CITY: Beijing China [CN].; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing CITY: Beijing China [CN].; Paris Diderot University CITY: Gif sur Yvette France [FR].; Noble Research Institute, LLC CITY: Ardmore STATE: Oklahoma POSTAL_CODE: 73401 United States Of America [US].; CNRS CITY: Gif-sur-Yvette France [FR].; China Agricultural University, Beijing, China CITY: Beijing STATE: Beijing POSTAL_CODE: 100193 China [CN].; State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University CITY: Beijing POSTAL_CODE: 100193 China [CN] wangt@cau.edu.cn.
Because of the high energy consumed during symbiotic nitrogen fixation, legumes must balance growth and symbiotic nodulation. Both lateral roots and nodules form on the root system and the developmental coordination of these organs according to reduced nitrogen (N) availability remains elusive. We show that the Compact Root Architecture 2 (MtCRA2) receptor-like kinase is essential to promote the initiation of early symbiotic nodulation and to inhibit root growth in response to low-N. MtCEP1 peptides can activate MtCRA2 under N-starvation conditions, leading to a repression of MtYUC2 auxin biosynthesis gene expression, and therefore of auxin root responses. Accordingly, the compact root architecture phenotype of cra2 can be mimicked by an auxin treatment or by over-expressing MtYUC2, and conversely, a treatment with YUC inhibitors or a MtYUC2 knock-out rescues the cra2 root phenotype. The MtCEP1-activated CRA2 can additionally interact with and phosphorylate the MtEIN2 ethylene signaling component at Ser643 and Ser924, preventing its cleavage and therefore repressing ethylene responses, thus locally promoting the root susceptibility to rhizobia. In agreement, the cra2 low nodulation phenotype is rescued by an ein2 mutation. Overall, by reducing auxin biosynthesis and inhibiting ethylene signaling, the MtCEP1/MtCRA2 pathway balances root and nodule development under low-N conditions.
PMID: 32586912
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Jun , V117 (26) : P15322-15331 doi: 10.1073/pnas.2003346117
Wounding-induced changes in cellular pressure and localized auxin signalling spatially coordinate restorative divisions in roots.
Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria.; Institute of Science and Technology Austria, 3400 Klosterneuburg, Austria jiri.friml@ist.ac.at.
Wound healing in plant tissues, consisting of rigid cell wall-encapsulated cells, represents a considerable challenge and occurs through largely unknown mechanisms distinct from those in animals. Owing to their inability to migrate, plant cells rely on targeted cell division and expansion to regenerate wounds. Strict coordination of these wound-induced responses is essential to ensure efficient, spatially restricted wound healing. Single-cell tracking by live imaging allowed us to gain mechanistic insight into the wound perception and coordination of wound responses after laser-based wounding in Arabidopsis root. We revealed a crucial contribution of the collapse of damaged cells in wound perception and detected an auxin increase specific to cells immediately adjacent to the wound. This localized auxin increase balances wound-induced cell expansion and restorative division rates in a dose-dependent manner, leading to tumorous overproliferation when the canonical TIR1 auxin signaling is disrupted. Auxin and wound-induced turgor pressure changes together also spatially define the activation of key components of regeneration, such as the transcription regulator ERF115. Our observations suggest that the wound signaling involves the sensing of collapse of damaged cells and a local auxin signaling activation to coordinate the downstream transcriptional responses in the immediate wound vicinity.
PMID: 32541049
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Jun , V117 (23) : P12784-12790 doi: 10.1073/pnas.2001211117
Loss of function of the Pad-1 aminotransferase gene, which is involved in auxin homeostasis, induces parthenocarpy in Solanaceae plants.
Institute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO), Tsu, 514-2392 Mie, Japan; mtosts@affrc.go.jp.; Institute of Vegetable and Floriculture Science, National Agriculture and Food Research Organization (NARO), Tsu, 514-2392 Mie, Japan.; Plant Breeding and Experiment Station, Takii and Company, Limited, Konan, 520-3231 Shiga, Japan.
Fruit development normally occurs after pollination and fertilization; however, in parthenocarpic plants, the ovary grows into the fruit without pollination and/or fertilization. Parthenocarpy has been recognized as a highly attractive agronomic trait because it could stabilize fruit yield under unfavorable environmental conditions. Although natural parthenocarpic varieties are useful for breeding Solanaceae plants, their use has been limited, and little is known about their molecular and biochemical mechanisms. Here, we report a parthenocarpic eggplant mutant, pad-1, which accumulates high levels of auxin in the ovaries. Map-based cloning showed that the wild-type (WT) Pad-1 gene encoded an aminotransferase with similarity to Arabidopsis VAS1 gene, which is involved in auxin homeostasis. Recombinant Pad-1 protein catalyzed the conversion of indole-3-pyruvic acid (IPyA) to tryptophan (Trp), which is a reverse reaction of auxin biosynthetic enzymes, tryptophan aminotransferases (TAA1/TARs). The RNA level of Pad-1 gene increased during ovary development and reached its highest level at anthesis stage in WT. This suggests that the role of Pad-1 in WT unpollinated ovary is to prevent overaccumulation of IAA resulting in precocious fruit-set. Furthermore, suppression of the orthologous genes of Pad-1 induced parthenocarpic fruit development in tomato and pepper plants. Our results demonstrated that the use of pad-1 genes would be powerful tools to improve fruit production of Solanaceae plants.
PMID: 32461365
New Phytol , IF:8.512 , 2020 Jun doi: 10.1111/nph.16778
PuHox52-mediated hierarchical multilayered gene regulatory network promotes adventitious root formation in Populus ussuriensis.
State Key Laboratory of Tree Genetics and Breeding, Northeast Forestry University, Harbin, 150040, China.; Anhui Province Key Laboratory of Medical Physics and Technology, Center of Medical Physics and Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230000, China.; Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510000, China.; College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI, 49931, USA.
Adventitious root (AR) formation is critically important in vegetative propagation through cuttings in some plants, especially woody species. However, the underlying molecular mechanisms remain elusive. Here, we report the identification of a poplar homeobox gene, PuHox52, which was rapidly induced (within 15 min) at the basal ends of stems upon cutting and played a key regulatory role in adventitious rooting. We demonstrated that overexpression of PuHox52 significantly increased the number of ARs while suppression of PuHox52 had the opposite effect. A multilayered hierarchical gene regulatory network (ML-hGRN) mediated by PuHox52 was reverse-engineered and demonstrated to govern AR formation process. PuHox52 regulated AR formation through up-regulation of nine hub regulators, including a jasmonate signaling pathway gene, PuMYC2. and an auxin signaling pathway gene, PuAGL12. We also identified coherent type 4 feed-forward loops within this ML-hGRN; PuHox52 repressed PuHDA9 that encodes a histone deacetylase and led to an increase in acetylation and presumably expression of three hub regulators, PuWRKY51, PuLBD21, and PuIAA7. Our results indicate that the ML-hGRN mediated by PuHox52 governs AR formation at the basal ends of stem cuttings from poplar trees.
PMID: 32589766
New Phytol , IF:8.512 , 2020 Jun doi: 10.1111/nph.16732
PIFs coordinate shade avoidance by inhibiting auxin repressor ARF18 and metabolic regulator QQS.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, College of Life Sciences, Shandong University, Qingdao, Shandong, 266237, China.; Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Shandong, 250014, China.; The key Laboratory of Plant Stress Biology, School of Life Science, Henan University, Kaifeng, 475004, China.; Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, 266237, China.; Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, Brno, 004205, Czech Republic.
Shade avoidance syndrome (SAS) arises in densely growing plants that compete for light. In Arabidopsis thaliana, phytochrome interacting factor (PIF) proteins link the perception of shade to stem elongation via auxin production. Here, we report that PIFs inhibit the shade-induced expression of AUXIN RESPONSE FACTOR 18 (ARF18), and ARF18 represses auxin signaling. Therefore, PIF-mediated inhibition of ARF18 enhances auxin-dependent hypocotyl elongation in simulated shade. Furthermore, we show that both PIFs and ARF18 directly repress qua-quine starch (QQS), which controls the allocation of carbon and nitrogen. Shade-repressed QQS attenuates the conversion of starch to protein and thus reduced leaf area. Our results suggest that PIF-dependent gene regulation coordinates multiple SAS responses, including altered stem growth via ARF18, as well as altered leaf growth and metabolism via QQS.
PMID: 32521046
New Phytol , IF:8.512 , 2020 Jun , V226 (6) : P1781-1795 doi: 10.1111/nph.16500
Auxin-activated MdARF5 induces the expression of ethylene biosynthetic genes to initiate apple fruit ripening.
College of Horticulture, Shenyang Agricultural University, Shenyang, 110866, China.; Liaoning Institute of Pomology, Xiongyue, 115009, China.
The gaseous plant hormone ethylene induces the ripening of climacteric fruit, including apple (Malus domestica). Another phytohormone, auxin, is known to promote ethylene production in many horticultural crops, but the regulatory mechanism remains unclear. Here, we found that auxin application induces ethylene production in apple fruit before the stage of commercial harvest, when they are not otherwise capable of ripening naturally. The expression of MdARF5, a member of the auxin response factor transcription factor (TF) family involved in the auxin signaling pathway, was enhanced by treatment with the synthetic auxin naphthaleneacetic acid (NAA). Further studies revealed that MdARF5 binds to the promoter of MdERF2, encoding a TF in the ethylene signaling pathway, as well as the promoters of two 1-aminocyclopropane-1-carboxylic acid synthase (ACS) genes (MdACS3a and MdACS1) and an ACC oxidase (ACO) gene, MdACO1, all of which encode key steps in ethylene biosynthesis, thereby inducing their expression. We also observed that auxin-induced ethylene production was dependent on the methylation of the MdACS3a promoter. Our findings reveal that auxin induces ethylene biosynthesis in apple fruit through activation of MdARF5 expression.
PMID: 32083754
New Phytol , IF:8.512 , 2020 Jun , V226 (6) : P1809-1821 doi: 10.1111/nph.16483
CEP receptor signalling controls root system architecture in Arabidopsis and Medicago.
Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia.; The Hounsfield Facility, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK.; Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, Universite, Paris Sud, Universite, Paris Diderot, INRA, Univ d'Evry, Universite Paris-Saclay, 91190, Gif-sur-Yvette, France.; School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK.
Root system architecture (RSA) influences the effectiveness of resources acquisition from soils but the genetic networks that control RSA remain largely unclear. We used rhizoboxes, X-ray computed tomography, grafting, auxin transport measurements and hormone quantification to demonstrate that Arabidopsis and Medicago CEP (C-TERMINALLY ENCODED PEPTIDE)-CEP RECEPTOR signalling controls RSA, the gravitropic set-point angle (GSA) of lateral roots (LRs), auxin levels and auxin transport. We showed that soil-grown Arabidopsis and Medicago CEP receptor mutants have a narrower RSA, which results from a steeper LR GSA. Grafting showed that CEPR1 in the shoot controls GSA. CEP receptor mutants exhibited an increase in rootward auxin transport and elevated shoot auxin levels. Consistently, the application of auxin to wild-type shoots induced a steeper GSA and auxin transport inhibitors counteracted the CEP receptor mutant's steep GSA phenotype. Concordantly, CEP peptides increased GSA and inhibited rootward auxin transport in wild-type but not in CEP receptor mutants. The results indicated that CEP-CEP receptor-dependent signalling outputs in Arabidopsis and Medicago control overall RSA, LR GSA, shoot auxin levels and rootward auxin transport. We propose that manipulating CEP signalling strength or CEP receptor downstream targets may provide means to alter RSA.
PMID: 32048296
New Phytol , IF:8.512 , 2020 Jun , V226 (6) : P1796-1808 doi: 10.1111/nph.16472
Hydrotropism in the primary roots of maize.
Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA.; College of Grassland Agriculture, Northwest A&F University, 712100, Yangling, China.; Department of Mathematics and Statistics, South Dakota State University, Brookings, SD, 57007, USA.; Department of Biology, Genetics Institute, Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL, 32610, USA.
Recent studies mainly in Arabidopsis have renewed interest and discussion in some of the key issues in hydrotropism of roots, such as the site of water sensing and the involvement of auxin. We examined hydrotropism in maize (Zea mays) primary roots. We determined the site of water sensing along the root using a nonintrusive method. Kinematic analysis was conducted to investigate spatial root elongation during hydrotropic response. Indole-3-acetic acid (IAA) and other hormones were quantified using LC-MS/MS. The transcriptome was analyzed using RNA sequencing. Main results: The very tip of the root is the most sensitive to the hydrostimulant. Hydrotropic bending involves coordinated adjustment of spatial cell elongation and cell flux. IAA redistribution occurred in maize roots, preceding hydrotropic bending. The redistribution is caused by a reduction of IAA content on the side facing a hydrostimulant, resulting in a higher IAA content on the dry side. Transcriptomic analysis of the elongation zone prior to bending identified IAA response and lignin synthesis/wall cross-linking as some of the key processes occurring during the early stages of hydrotropic response. We conclude that maize roots differ from Arabidopsis in the location of hydrostimulant sensing and the involvement of IAA redistribution.
PMID: 32020611
New Phytol , IF:8.512 , 2020 Jun , V226 (6) : P1753-1765 doi: 10.1111/nph.16463
Conifers exhibit a characteristic inactivation of auxin to maintain tissue homeostasis.
Umea Plant Science Centre, Department of Plant Physiology, Umea University (Umu), 90736, Umea, Sweden.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences (SLU), 90183, Umea, Sweden.; Laboratory of Growth Regulators, Faculty of Science, Palacky University & Institute of Experimental Botany, The Czech Academy of Sciences, Slechtitelu 27, CZ-78371, Olomouc, Czech Republic.; Departmebt of Chemical Biology and Genetics, Faculty of Science, Centre of the Region Hana for Biotechnological and Agricultural Research, Palacky University, CZ-78371, Olomouc, Czech Republic.; Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Universite Paris-Saclay, 78000, Versailles, France.
Dynamic regulation of the concentration of the natural auxin (IAA) is essential to coordinate most of the physiological and developmental processes and responses to environmental changes. Oxidation of IAA is a major pathway to control auxin concentrations in angiosperms and, along with IAA conjugation, to respond to perturbation of IAA homeostasis. However, these regulatory mechanisms remain poorly investigated in conifers. To reduce this knowledge gap, we investigated the different contributions of the IAA inactivation pathways in conifers. MS-based quantification of IAA metabolites under steady-state conditions and after perturbation was investigated to evaluate IAA homeostasis in conifers. Putative Picea abies GH3 genes (PaGH3) were identified based on a comprehensive phylogenetic analysis including angiosperms and basal land plants. Auxin-inducible PaGH3 genes were identified by expression analysis and their IAA-conjugating activity was explored. Compared to Arabidopsis, oxidative and conjugative pathways differentially contribute to reduce IAA concentrations in conifers. We demonstrated that the oxidation pathway plays a marginal role in controlling IAA homeostasis in spruce. By contrast, an excess of IAA rapidly activates GH3-mediated irreversible conjugation pathways. Taken together, these data indicate that a diversification of IAA inactivation mechanisms evolved specifically in conifers.
PMID: 32004385
New Phytol , IF:8.512 , 2020 Jun , V226 (5) : P1375-1383 doi: 10.1111/nph.16446
Auxin canalization and vascular tissue formation by TIR1/AFB-mediated auxin signaling in Arabidopsis.
University of Silesia in Katowice, Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, Katowice, Poland.; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, CZ-62-500, Brno, Czech Republic.; Institute of Science and Technology (IST), 3400, Klosterneuburg, Austria.; Laboratory of Growth Regulators and Department of Chemical Biology and Genetics, Centre of Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 27, 783 71, Olomouc, Czech Republic.
Plant survival depends on vascular tissues, which originate in a self-organizing manner as strands of cells co-directionally transporting the plant hormone auxin. The latter phenomenon (also known as auxin canalization) is classically hypothesized to be regulated by auxin itself via the effect of this hormone on the polarity of its own intercellular transport. Correlative observations supported this concept, but molecular insights remain limited. In the current study, we established an experimental system based on the model Arabidopsis thaliana, which exhibits auxin transport channels and formation of vasculature strands in response to local auxin application. Our methodology permits the genetic analysis of auxin canalization under controllable experimental conditions. By utilizing this opportunity, we confirmed the dependence of auxin canalization on a PIN-dependent auxin transport and nuclear, TIR1/AFB-mediated auxin signaling. We also show that leaf venation and auxin-mediated PIN repolarization in the root require TIR1/AFB signaling. Further studies based on this experimental system are likely to yield better understanding of the mechanisms underlying auxin transport polarization in other developmental contexts.
PMID: 31971254
Curr Opin Plant Biol , IF:8.356 , 2020 Jun , V55 : P21-27 doi: 10.1016/j.pbi.2020.02.002
Old Town Roads: routes of auxin biosynthesis across kingdoms.
Department of Biology, Washington University, St. Louis, MO 63130, United States; Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, MO 63130, United States. Electronic address: nmorffy@wustl.edu.; Department of Biology, Washington University, St. Louis, MO 63130, United States; Center for Science and Engineering Living Systems (CSELS), Washington University, St. Louis, MO 63130, United States; Center for Engineering MechanoBiology, Washington University, St. Louis, MO 63130, United States. Electronic address: strader@wustl.edu.
Auxin is an important signaling molecule synthesized in organisms from multiple kingdoms of life, including land plants, green algae, and bacteria. In this review, we highlight the similarities and differences in auxin biosynthesis among these organisms. Tryptophan-dependent routes to IAA are found in land plants, green algae and bacteria. Recent sequencing efforts show that the indole-3-pyruvic acid pathway, one of the primary biosynthetic pathways in land plants, is also found in the green algae. These similarities raise questions about the origin of auxin biosynthesis. Future studies comparing auxin biosynthesis across kingdoms will shed light on its origin and role outside of the plant lineage.
PMID: 32199307
EMBO Rep , IF:7.497 , 2020 Jun , V21 (6) : Pe50164 doi: 10.15252/embr.202050164
KUP9 maintains root meristem activity by regulating K(+) and auxin homeostasis in response to low K.
State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, China.; The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, College of Life Sciences, Shandong University, Qingdao, China.
Potassium (K) is essential for plant growth and development. Here, we show that the KUP/HAK/KT K(+) transporter KUP9 controls primary root growth in Arabidopsis thaliana. Under low-K(+) conditions, kup9 mutants displayed a short-root phenotype that resulted from reduced numbers of root cells. KUP9 was highly expressed in roots and specifically expressed in quiescent center (QC) cells in root tips. The QC acts to maintain root meristem activity, and low-K(+) conditions induced QC cell division in kup9 mutants, resulting in impaired root meristem activity. The short-root phenotype and enhanced QC cell division in kup9 mutants could be rescued by exogenous auxin treatment or by specifically increasing auxin levels in QC cells, suggesting that KUP9 affects auxin homeostasis in QC cells. Further studies showed that KUP9 mainly localized to the endoplasmic reticulum (ER), where it mediated K(+) and auxin efflux from the ER lumen to the cytoplasm in QC cells under low-K(+) conditions. These results demonstrate that KUP9 maintains Arabidopsis root meristem activity and root growth by regulating K(+) and auxin homeostasis in response to low-K(+) stress.
PMID: 32250038
Plant Physiol , IF:6.902 , 2020 Jun doi: 10.1104/pp.20.00302
Rice GROWTH-REGULATING FACTOR7 Modulates Plant Architecture through Regulating GA and IAA Metabolism.
Wuhan University CITY: Wuhan STATE: Hubei China [CN].; Wuhan University CITY: Wuhan STATE: Hubei POSTAL_CODE: 430072 China [CN].; Wuhan University CITY: Wuhan STATE: Hubei China [CN] shaoqingli@whu.edu.cn.
Plant-specific GROWTH-REGULATING FACTORs (GRFs) participate in central developmental processes, including leaf and root development; inflorescence, flower and seed formation; senescence; and tolerance to stresses. In rice (Oryza sativa), there are 12 GRFs, but the role of the miR396-OsGRF7 regulatory module remains unknown. Here, we report that OsGRF7 shapes plant architecture via the regulation of auxin and gibberellin metabolism in rice. OsGRF7 is mainly expressed in lamina joints, nodes, internodes, axillary buds, and young inflorescences. Overexpression of OsGRF7 causes a semidwarf and compact plant architecture with an increased culm wall thickness and narrowed leaf angles mediated by shortened cell length, altered cell arrangement, and increased parenchymal cell layers in the culm and adaxial side of the lamina joints. Knock-out and knock-down lines of OsGRF7 exhibit contrasting phenotypes with severe degradation of parenchymal cells in the culm and lamina joints at maturity. Further analysis indicated that OsGRF7 binds the ACRGDA motif in the promoters of Cytochrome P450 gene (OsCYP714B1) and AUXIN RESPONSE FACTOR 12 (OsARF12), which are involved in the gibberellin synthesis and auxin signaling pathways, respectively. Correspondingly, OsGRF7 alters the contents of endogenous gibberellins and auxins and sensitivity to exogenous phytohormones. These findings establish OsGRF7 as a crucial component in the OsmiR396-OsGRF-plant hormone regulatory network that controls rice plant architecture.
PMID: 32581114
Plant Physiol , IF:6.902 , 2020 Jun doi: 10.1104/pp.20.00243
Low blue light enhances phototropism by releasing cryptochrome 1-mediated inhibition of PIF4 expression.
University of Lausanne CITY: CH-1015 Lausanne Switzerland [CH].; Fundacion Instituto Leloir CITY: Ciudad de Buenos Aires Argentina [AR].; Laboratoire Reproduction et Developpement des Plantes, ENS de Lyon, CNRS CITY: Lyon France [FR].; Ecole Normale Superieure de Lyon CITY: Lyon POSTAL_CODE: 69364 France [FR].; IFEVA, Facultad de Agronomia, Universidad de Buenos Aires, 1417 CITY: Buenos Aires Argentina [AR].; Universidad de Buenos Aires CITY: Buenos Aires Argentina [AR].; University of Lausanne CITY: CH-1015 Lausanne POSTAL_CODE: . Switzerland [CH] christian.fankhauser@unil.ch.
Shade-avoiding plants, including Arabidopsis (Arabidopsis thaliana), display a number of growth responses, such as elongation of stem-like structures and repositioning of leaves, elicited by shade cues, including a reduction in the blue and red portions of the solar spectrum and a low red to far-red ratio. Shade also promotes phototropism of de-etiolated seedlings through repression of phytochrome B (phyB), presumably to enhance capture of unfiltered sunlight. Here we show that both low blue light and a low red to far-red light ratio are required to rapidly enhance phototropism in Arabidopsis seedlings. However, prolonged low blue light treatments are sufficient to promote phototropism through reduced cryptochrome 1 (cry1) activation. The enhanced phototropic response of cry1 mutants in the lab and in response to natural canopies depends on PHYTOCHROME INTERACTING FACTORs (PIFs). In favorable light conditions, cry1 limits the expression of PIF4, while in low blue light PIF4 expression increases, which contributes to phototropic enhancement. The analysis of quantitative DII-Venus, an auxin signaling reporter, indicates that low blue light leads to enhanced auxin signaling in the hypocotyl and, upon phototropic stimulation, a steeper auxin signaling gradient across the hypocotyl. We conclude that phototropic enhancement by canopy shade results from the combined activities of phytochrome B and cry1 that converge on PIF regulation.
PMID: 32554507
Plant Physiol , IF:6.902 , 2020 Jun , V183 (2) : P416-417 doi: 10.1104/pp.20.00489
Mix, Match, and Maize: A Synthetic System for Maize Nuclear Auxin Response Circuits.
Donald Danforth Plant Science Center, Saint Louis, Missouri 63132 dthiruppathi@danforthcenter.org.
PMID: 32493797
Plant Physiol , IF:6.902 , 2020 Jun doi: 10.1104/pp.20.00251
Conversion of unstable compounds can contribute to the auxin pool during sample preparation.
University of Tasmania CITY: Hobart STATE: TAS Australia [AU].; University of Tasmania School of Biological Sciences, POB 252-55, Churchill Avenue CITY: Hobart STATE: TAS POSTAL_CODE: 7001 Australia [AU] john.ross@utas.edu.au.
PMID: 32482907
Semin Cell Dev Biol , IF:6.691 , 2020 Jun doi: 10.1016/j.semcdb.2020.06.011
There and back again: An evolutionary perspective on long-distance coordination of plant growth and development.
School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.; School of Biology, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK. Electronic address: t.a.bennett@leeds.ac.uk.
Vascular plants, unlike bryophytes, have a strong root-shoot dichotomy in which the tissue systems are mutually interdependent; roots are completely dependent on shoots for photosynthetic sugars, and shoots are completely dependent on roots for water and mineral nutrients. Long-distance communication between shoot and root is therefore critical for the growth, development and survival of vascular plants, especially with regard to variable environmental conditions. However, this long-distance signalling does not appear an ancestral feature of land plants, and has likely arisen in vascular plants to service the radical alterations in body-plan seen in this taxon. In this review, we examine the defined hormonal root-to-shoot and shoot-to-root signalling pathways that coordinate the growth of vascular plants, with a particular view to understanding how these pathways may have evolved. We highlight the completely divergent roles of isopentenyl-adenine and trans-zeatin cytokinin species in long-distance signalling, and ask whether cytokinin can really be considered as a single class of hormones in the light of recent research. We also discuss the puzzlingly sparse evidence for auxin as a shoot-to-root signal, the evolutionary re-purposing of strigolactones and gibberellins as hormonal signals, and speculate on the possible role of sugars as long-distance signals. We conclude by discussing the 'design principles' of long-distance signalling in vascular plants.
PMID: 32576500
Plant Cell Environ , IF:6.362 , 2020 Jun doi: 10.1111/pce.13824
PIF4 and PIF5 regulate axillary branching via bud abscisic acid and stem auxin signaling.
Department of Plant and Microbial Biology, University of California Berkeley, CA, U.S.A.; Department of Soil and Crop Sciences, Texas A&M University and Texas A&M AgriLife Research, College Station, TX, U.S.A.; Libertyville, Illinois, U.S.A.
The ratio of red light to far-red light (R:FR) is perceived by phytochrome B (phyB) and informs plants of nearby competition. A low R:FR indicative of competition induces the shade avoidance syndrome and suppresses branching by incompletely understood mechanisms. PHYTOCHROME INTERACTING FACTORs (PIFs) are transcription factors targeted by phytochromes to evoke photomorphogenic responses. PIF4 and PIF5 promote shade avoidance responses and become inactivated by direct interaction with active phyB in the nucleus. Here, genetic and physiological assays show that PIF4 and PIF5 contribute to the suppression of branching resulting from phyB loss of function and a low R:FR, though roles for other PIFs or pathways may exist. The suppression of branching is associated with PIF4/PIF5 promotion of the expression of the branching inhibitor BRANCHED 1 and abscisic acid (ABA) accumulation in axillary buds, and is dependent on the function of the key ABA biosynthetic enzyme NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3. However, PIF4/PIF5 function is not confined to a single hormonal pathway, as they also promote stem indole-3-acetic acid accumulation and stimulate systemic auxin signaling, which contribute to the suppression of bud growth when phyB is inactive. This article is protected by copyright. All rights reserved.
PMID: 32542798
Plant Cell Environ , IF:6.362 , 2020 Jun doi: 10.1111/pce.13820
Balancing of hormonal biosynthesis and catabolism pathways, a strategy to ameliorate the negative effects of heat stress on reproductive growth.
Plant BioSystems, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada.
In pea (Pisum sativum L.), moderate heat stress during early flowering/fruit set increased seed/ovule abortion, and concomitantly produced fruits with reduced ovary (pericarp) length, and fewer seeds at maturity. Plant hormonal networks coordinate seed and pericarp growth and development. To determine if these hormonal networks are modulated in response to heat stress, we analyzed the gene expression patterns and associated these patterns with precursors, and bioactive and inactive metabolites of the auxin, gibberellin (GA), abscisic acid (ABA), and ethylene biosynthesis/catabolism pathways in young developing seeds and pericarps of non-stressed and 4-day heat-stressed fruits. Our data suggest that within the developing seeds heat stress decreased bioactive GA levels reducing GA growth-related processes, and that increased ethylene levels may have promoted this inhibitory response. In contrast, heat stress increased auxin biosynthesis gene expression and auxin levels in the seeds and pericarps, and seed ABA levels, both effects can increase seed sink strength. We hypothesize that seeds with higher auxin- and ABA-induced sink strength and adequate bioactive GA levels will set and continue to grow, while the seeds with lower sink strength (low auxin, ABA, and GA levels) will become more sensitive to heat stress-induced ethylene leading to ovule/seed abortion. This article is protected by copyright. All rights reserved.
PMID: 32515497
Plant Cell Environ , IF:6.362 , 2020 Jun doi: 10.1111/pce.13817
Volatiles from the fungal phytopathogen Penicillium aurantiogriseum modulate root metabolism and architecture through proteome resetting.
Instituto de Agrobiotecnologia (Consejo Superior de Investigaciones Cientificas/Gobierno de Navarra), Avenida de Pamplona 123, 31192 Mutilva, Navarra, Spain.; Department of Chemical Biology and Genetics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, Olomouc CZ-78371, Czech Republic.; Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), OT Gatersleben, Corrensstr. 3, D-06466 Stadt Seeland, Germany.; Instituto de Bioquimica Vegetal y Fotosintesis, Consejo Superior de Investigaciones Cientificas and Universidad de Sevilla, Avenida Americo Vespucio, 49, Sevilla, Spain.
Volatile compounds (VCs) emitted by the fungal phytopathogen Penicillium aurantiogriseum promote root growth and developmental changes in Arabidopsis. Here we characterized the metabolic and molecular responses of roots to fungal volatiles. Proteomic analyses revealed that these compounds reduce the levels of aquaporins, the iron carrier IRT1 and apoplastic peroxidases. Fungal VCs also increased the levels of enzymes involved in the production of mevalonate (MVA)-derived isoprenoids, nitrogen assimilation and conversion of methionine to ethylene and cyanide. Consistently, fungal VC-treated roots accumulated high levels of hydrogen peroxide (H2 O2 ), MVA-derived cytokinins, ethylene, cyanide and long-distance nitrogen transport amino acids. qRT-PCR analyses showed that many proteins differentially expressed by fungal VCs are encoded by VC non-responsive genes. Expression patterns of hormone reporters and developmental characterization of mutants provided evidence for the involvement of cyanide scavenging and enhanced auxin, ethylene, cytokinin and H2 O2 signaling in the root architecture changes promoted by fungal VCs. Our findings show that VCs from P. aurantiogriseum modify root metabolism and architecture, and improve nutrient and water use efficiencies through transcriptionally and non-transcriptionally regulated proteome resetting mechanisms. Some of these mechanisms are subject to long-distance regulation by photosynthesis and differ from those triggered by VCs emitted by beneficial microorganisms.
PMID: 32515071
Plant Cell Environ , IF:6.362 , 2020 Jun doi: 10.1111/pce.13814
Root isoprene formation alters lateral root development.
Research Unit Environmental Simulation, Institute of Biochemical Plant Pathology, Helmholtz Zentrum Munchen, Neuherberg, Germany.; Research Unit Protein Science, Helmholtz Zentrum Munchen, Neuherberg, Germany.; Forest Botany, Albert-Ludwigs-Universitat Freiburg, Freiburg im Breisgau, Germany.; Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China.; Forest Botany and Tree Physiology, University of Gottingen, Gottingen, Germany.
Isoprene is a C5 volatile organic compound, which can protect aboveground plant tissue from abiotic stress such as short-term high temperatures and accumulation of reactive oxygen species (ROS). Here, we uncover new roles for isoprene in the plant belowground tissues. By analysing Populus x canescens isoprene synthase (PcISPS) promoter reporter plants, we discovered PcISPS promoter activity in certain regions of the roots including the vascular tissue, the differentiation zone and the root cap. Treatment of roots with auxin or salt increased PcISPS promoter activity at these sites, especially in the developing lateral roots (LR). Transgenic, isoprene non-emitting poplar roots revealed an accumulation of O2 (-) in the same root regions where PcISPS promoter activity was localized. Absence of isoprene emission, moreover, increased the formation of LRs. Inhibition of NAD(P)H oxidase activity suppressed LR development, suggesting the involvement of ROS in this process. The analysis of the fine root proteome revealed a constitutive shift in the amount of several redox balance, signalling and development related proteins, such as superoxide dismutase, various peroxidases and linoleate 9S-lipoxygenase, in isoprene non-emitting poplar roots. Together our results indicate for isoprene a ROS-related function, eventually co-regulating the plant-internal signalling network and development processes in root tissue.
PMID: 32495947
Plant Cell Environ , IF:6.362 , 2020 Jun , V43 (6) : P1545-1557 doi: 10.1111/pce.13738
Sugar enhances waterlogging-induced adventitious root formation in cucumber by promoting auxin transport and signalling.
Department of Horticulture, School of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China.; Department of Food Science, School of Food Science and Engineering, Yangzhou University, Yangzhou, China.
Waterlogging is a severe environmental stress that causes severe crop productivity losses. Cucumber (Cucumis sativus L.) survives waterlogging by producing adventitious roots (ARs) that enhance gas exchange. Little is known about the role of light and sugars in the waterlogging-induced production of ARs. The role of these factors in AR production was therefore studied in cucumber seedlings grown in the absence or presence of waterlogging and different light conditions. The effect of photosynthesis was studied by removing the shoots of the seedlings and replacing them with exogenous applications of sucrose or stachyose. Shoot removal inhibited AR emergence and elongation. However, the exogenous application of sugars fully restored AR emergence and partially restored root elongation. The exogenous application of a synthetic auxin restored AR emergence but not AR elongation. Transcriptome profiling analysis was used to determine the effects of light on gene expression in the hypocotyls under these conditions. The levels of transcripts encoding proteins involved in auxin transport and signalling were higher in the light and following the exogenous application of sucrose and stachyose. These results show that the waterlogging-induced emergence of ARs is regulated by the interaction between sugars and auxin, whereas AR elongation depends only on sugars alone.
PMID: 32020637
Plant J , IF:6.141 , 2020 Jun doi: 10.1111/tpj.14875
Barley HISTIDINE KINASE 1 (HvHK1) coordinates transfer cell specification in the young endosperm.
Department of Physiology and Cell Biology, Leibniz Institute for Plant Genetics and Crop Plant Research (IPK), Seeland/OT Gatersleben, D-06466, Germany.; Department of Molecular Genetics, Leibniz Institute for Plant Genetics and Crop Plant Research (IPK), Seeland/OT Gatersleben, D-06466, Germany.
Cereal endosperm represents the most important source of the world's food; nevertheless, the molecular mechanisms underlying cell and tissue differentiation in cereal grains remain poorly understood. Endosperm cellularization commences at the maternal-filial intersection of grains and generates endosperm transfer cells (ETCs), a cell type with a prominent anatomy optimized for efficient nutrient transport. Barley HISTIDINE KINASE1 (HvHK1) was identified as a receptor component with spatially restricted expression in the syncytial endosperm where ETCs emerge. Here, we demonstrate its function in ETC fate acquisition using RNA interference-mediated downregulation of HvHK1. Repression of HvHK1 impairs cell specification in the central ETC region and the development of transfer cell morphology, and consecutively defects differentiation of adjacent endosperm tissues. Coinciding with reduced expression of HvHK1, disturbed cell plate formation and fusion were observed at the initiation of endosperm cellularization, revealing that HvHK1 triggers initial cytokinesis of ETCs. Cell-type-specific RNA sequencing confirmed loss of transfer cell identity, compromised cell wall biogenesis and reduced transport capacities in aberrant cells and elucidated two-component signaling and hormone pathways that are mediated by HvHK1. Gene regulatory network modeling was used to specify the direct targets of HvHK1; this predicted non-canonical auxin signaling elements as the main regulatory links governing cellularization of ETCs, potentially through interaction with type-B response regulators. This work provides clues to previously unknown molecular mechanisms directing ETC specification, a process with fundamental impact on grain yield in cereals.
PMID: 32530511
Plant J , IF:6.141 , 2020 Jun , V102 (6) : P1172-1186 doi: 10.1111/tpj.14690
ATP binding cassette transporters ABCG1 and ABCG16 affect reproductive development via auxin signalling in Arabidopsis.
Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.; College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Laboratory of Sugarcane Biology, College of Agriculture, Guangxi University, Nanning, 530004, China.; College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Angiosperm reproductive development is a complex event that includes floral organ development, male and female gametophyte formation and interaction between the male and female reproductive organs for successful fertilization. Previous studies have revealed the redundant function of ATP binding cassette subfamily G (ABCG) transporters ABCG1 and ABCG16 in pollen development, but whether they are involved in other reproductive processes is unknown. Here we show that ABCG1 and ABCG16 were not only expressed in anthers and stamen filaments but also enriched in pistil tissues, including the stigma, style, transmitting tract and ovule. We further demonstrated that pistil-expressed ABCG1 and ABCG16 promoted rapid pollen tube growth through their effects on auxin distribution and auxin flow in the pistil. Moreover, disrupted auxin homeostasis in stamen filaments was associated with defective filament elongation. Our work reveals the key functions of ABCG1 and ABCG16 in reproductive development and provides clues for identifying ABCG1 and ABCG16 substrates in Arabidopsis.
PMID: 31944421
Plant J , IF:6.141 , 2020 Jun , V102 (5) : P1026-1041 doi: 10.1111/tpj.14684
Regulation of ovule initiation by gibberellins and brassinosteroids in tomato and Arabidopsis: two plant species, two molecular mechanisms.
Instituto de Biologia Molecular y Celular de Plantas (IBMCP), Universidad Politecnica de Valencia (UPV)-Consejo Superior de Investigaciones Cientificas (CSIC), CPI 8E, Ingeniero Fausto Elio s/n, 46022, Valencia, Spain.; Department of Plant and Microbial Biology, Program in Genetics, North Carolina State, Raleigh, NC, USA.
Ovule primordia formation is a complex developmental process with a strong impact on the production of seeds. In Arabidopsis this process is controlled by a gene network, including components of the signalling pathways of auxin, brassinosteroids (BRs) and cytokinins. Recently, we have shown that gibberellins (GAs) also play an important role in ovule primordia initiation, inhibiting ovule formation in both Arabidopsis and tomato. Here we reveal that BRs also participate in the control of ovule initiation in tomato, by promoting an increase on ovule primordia formation. Moreover, molecular and genetic analyses of the co-regulation by GAs and BRs of the control of ovule initiation indicate that two different mechanisms occur in tomato and Arabidopsis. In tomato, GAs act downstream of BRs. BRs regulate ovule number through the downregulation of GA biosynthesis, which provokes stabilization of DELLA proteins that will finally promote ovule primordia initiation. In contrast, in Arabidopsis both GAs and BRs regulate ovule number independently of the activity levels of the other hormone. Taken together, our data strongly suggest that different molecular mechanisms could operate in different plant species to regulate identical developmental processes even, as for ovule primordia initiation, if the same set of hormones trigger similar responses, adding a new level of complexity.
PMID: 31930587
Plant J , IF:6.141 , 2020 Jun , V102 (5) : P948-964 doi: 10.1111/tpj.14677
Rice siR109944 suppresses plant immunity to sheath blight and impacts multiple agronomic traits by affecting auxin homeostasis.
College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.; Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, 210095, China.; Department of Microbiology & Plant Pathology, University of California, Riverside, CA, 92521, USA.
Plant small RNAs (sRNAs) play significant roles in regulating various developmental processes and hormone signalling pathways involved in plant responses to a wide range of biotic and abiotic stresses. However, the functions of sRNAs in response to rice sheath blight remain unclear. We screened rice (Oryza sativa) sRNA expression patterns against Rhizoctonia solani and found that Tourist-miniature inverted-repeat transposable element (MITE)-derived small interfering RNA (siRNA) (here referred to as siR109944) expression was clearly suppressed upon R. solani infection. One potential target of siR109944 is the F-Box domain and LRR-containing protein 55 (FBL55), which encode the transport inhibitor response 1 (TIR1)-like protein. We found that rice had significantly enhanced susceptibility when siR109944 was overexpressed, while FBL55 OE plants showed resistance to R. solani challenge. Additionally, multiple agronomic traits of rice, including root length and flag leaf inclination, were affected by siR109944 expression. Auxin metabolism-related and signalling pathway-related genes were differentially expressed in the siR109944 OE and FBL55 OE plants. Importantly, pre-treatment with auxin enhanced sheath blight resistance by affecting endogenous auxin homeostasis in rice. Furthermore, transgenic Arabidopsis overexpressing siR109944 exhibited early flowering, increased tiller numbers, and increased susceptibility to R. solani. Our results demonstrate that siR109944 has a conserved function in interfering with plant immunity, growth, and development by affecting auxin homeostasis in planta. Thus, siR109944 provides a genetic target for plant breeding in the future. Furthermore, exogenous application of indole-3-acetic acid (IAA) or auxin analogues might effectively protect field crops against diseases.
PMID: 31923320
J Exp Bot , IF:5.908 , 2020 Jun , V71 (12) : P3383-3385 doi: 10.1093/jxb/eraa178
The quick and the dead: a new model for the essential role of ABA accumulation in synthetic auxin herbicide mode of action.
Colorado State University, Department of Agricultural Biology, Fort Collins, CO, USA.
PMID: 32569383
J Exp Bot , IF:5.908 , 2020 Jun , V71 (11) : P3241-3246 doi: 10.1093/jxb/eraa196
Understanding the algae to land plant transition.
University of Osnabruck, Division of Botany, Osnabruck, Germany.; University of Innsbruck, Department of Botany, Innsbruck, Austria.
PMID: 32529251
J Exp Bot , IF:5.908 , 2020 Jun , V71 (12) : P3512-3523 doi: 10.1093/jxb/eraa119
EARLY BUD BREAK 1 triggers bud break in peach trees by regulating hormone metabolism, the cell cycle, and cell wall modifications.
College of Horticulture Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, China.; State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, Shandong, China.; Shandong Collaborative Innovation Center for Fruit & Vegetable Production with High Quality and Efficiency, Tai'an, Shandong, China.; Laiyang City Bureau of Natural Resources and Planning, Yantai, Shangdong, China.
In a previous study we identified EARLY BUD BREAK 1 (EBB1), an ERF transcription factor, in peach (Prunus persica var. nectarina cultivar Zhongyou 4); however, little is known of how PpEBB1 may regulate bud break. To verify the function of PpEBB1 in bud break, PpEBB1 was transiently transformed into peach buds, resulting in early bud break. Bud break occurred earlier in PpEBB1-oe poplar (Populus trichocarpa) obtained by heterologous transformation than in wild type (WT), consistent with the peach bud results, indicating that PpEBB1 can promote bud break. To explore how PpEBB1 affects bud break, differentially expressed genes (DEGs) between WT and PpEBB1-oe poplar plants were identified by RNA-sequencing. The expression of DEGs associated with hormone metabolism, cell cycle, and cell wall modifications changed substantially according to qRT-PCR. Auxin, ABA, and total trans-zeatin-type cytokinin levels were higher in the PpEBB1-oe plants than in WT plants, while the total N6-(Delta 2-isopentenyl)-adenine-type cytokinins was lower. Yeast two-hybrid and bimolecular fluorescence complementation assays verified that a cell wall modification-related protein (PpEXBL1) interacted with PpEBB1 suggesting that PpEBB1 could interact with these cell wall modification proteins directly. Overall, our study proposed a multifaceted explanation for how PpEBB1 regulates bud break and showed that PpEBB1 promotes bud break by regulating hormone metabolism, the cell cycle, and cell wall modifications.
PMID: 32507879
J Exp Bot , IF:5.908 , 2020 Jun doi: 10.1093/jxb/eraa256
The amino acid transporter OsAAP1 mediates growth and grain yield by regulating neutral amino acids uptake and reallocation in Oryza sativa.
State Key Laboratory of Genetic Engineering, Department of Genetics, School of Life Sciences, Fudan University, Shanghai, China.; National Key Laboratory of Crop Genetic Improvement, Center of Integrative Biology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.; Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Agricultural Sciences, Guizhou University, Guiyang, China.
Nitrogen (N) is a major element necessary for crop yield. In most plants, organic nitrogen is primarily transported in the form of amino acids. Here, we show that OsAAP1 (Amino Acid Permease 1) functions as a positive regulator of growth and grain yield in rice. We found that the OsAAP1 gene is highly expressed in rice axillary buds, leaves, and young panicles and that the OsAAP1 protein is localized to both the plasma membrane and the nuclear membrane. Compared with the wild type ZH11, OsAAP1 overexpressing (OE) lines exhibited increased filled grain numbers as a result of enhanced tillering while RNA interference (RNAi) and CRISPR (Osaap1) knockout lines showed the opposite phenotype. In addition, OsAAP1-OE lines had higher concentrations of neutral and acidic amino acids, but lower concentrations of basic amino acids in the straw. An exogenous treatment with neutral amino acids more strongly promoted axillary bud outgrowth in the OE lines than that in the WT, RNAi or Osaap1 lines. Transcriptome analysis of Osaap1 further demonstrated that OsAAP1 may affect the nitrogen transport and metabolism, auxin, cytokinin and strigolactone signaling in regulating rice tillering. Taken together, these results support that increasing neutral amino acid uptake and reallocation via OsAAP1 could improve growth and grain yield in rice.
PMID: 32485736
J Exp Bot , IF:5.908 , 2020 Jun , V71 (13) : P3843-3853 doi: 10.1093/jxb/eraa241
Auxin-mediated responses under salt stress: from developmental regulation to biotechnological applications.
Departamento de Genetica Molecular y Microbiologia, Facultad de Ciencias Biologicas and Departamento de Fruticultura y Enologia, Facultad de Agronomia e Ingenieria Forestal. Pontificia Universidad Catolica de Chile, Avenida Libertador Bernardo O'Higgins, Santiago, Chile.
As sessile organisms, plants are exposed to multiple abiotic stresses commonly found in nature. To survive, plants have developed complex responses that involve genetic, epigenetic, cellular, and morphological modifications. Among different environmental cues, salt stress has emerged as a critical problem contributing to yield losses and marked reductions in crop production. Moreover, as the climate changes, it is expected that salt stress will have a significant impact on crop production in the agroindustry. On a mechanistic level, salt stress is known to be regulated by the crosstalk of many signaling molecules such as phytohormones, with auxin having been described as a key mediator of the process. Auxin plays an important role in plant developmental responses and stress, modulating a complex balance of biosynthesis, transport, and signaling that among other things, finely tune physiological changes in plant architecture and Na+ accumulation. In this review, we describe current knowledge on auxin's role in modulating the salt stress response. We also discuss recent and potential biotechnological approaches to tackling salt stress.
PMID: 32433743
J Exp Bot , IF:5.908 , 2020 Jun , V71 (11) : P3287-3295 doi: 10.1093/jxb/eraa169
The evolutionary origins of auxin transport: what we know and what we need to know.
Department of Experimental Plant Biology, Faculty of Science, Charles University, Vinicna, Czech Republic.; The Czech Academy of Sciences, Institute of Experimental Botany, Rozvojova, Czech Republic.
Auxin, represented by indole-3-acetic acid (IAA), has for a long time been studied mainly with respect to the development of land plants, and recent evidence confirms that canonical nuclear auxin signaling is a land plant apomorphy. Increasing sequential and physiological data show that the presence of auxin transport machinery pre-dates the emergence of canonical signaling. In this review, we summarize the present state of knowledge regarding the origins of auxin transport in the green lineage (Viridiplantae), integrating both data from wet lab experiments and sequence evidence on the presence of PIN-FORMED (PIN), PIN-LIKES (PILS), and AUXIN RESISTANT 1/LIKE-AUX1 (AUX1/LAX) homologs. We discuss a high divergence of auxin carrier homologs among algal lineages and emphasize the urgent need for the establishment of good molecular biology models from within the streptophyte green algae. We further postulate and discuss two hypotheses for the ancestral role of auxin in the green lineage. First, auxin was present as a by-product of cell metabolism and the evolution of its transport was stimulated by the need for IAA sequestration and cell detoxification. Second, auxin was primarily a signaling compound, possibly of bacterial origin, and its activity in the pre-plant green algae was a consequence of long-term co-existence with bacteria in shared ecological consortia.
PMID: 32246155
J Exp Bot , IF:5.908 , 2020 Jun , V71 (12) : P3701-3709 doi: 10.1093/jxb/eraa124
Transcriptomics in Erigeron canadensis reveals rapid photosynthetic and hormonal responses to auxin herbicide application.
Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA.; Bioinformatics Core, Purdue University, West Lafayette, IN, USA.
The perception pathway for endogenous auxin has been well described, yet the mode of action of synthetic auxin herbicides, used for >70 years, remains uncharacterized. We utilized transcriptomics and targeted physiological studies to investigate the unknown rapid response to synthetic auxin herbicides in the globally problematic weed species Erigeron canadensis. Synthetic auxin herbicide application consistently and rapidly down-regulated the photosynthetic machinery. At the same time, there was considerable perturbation to the expression of many genes related to phytohormone metabolism and perception. In particular, auxin herbicide application enhanced the expression of the key abscisic acid biosynthetic gene, 9-cis-epoxycarotenoid deoxygenase (NCED). The increase in NCED expression following auxin herbicide application led to a rapid biosynthesis of abscisic acid (ABA). This increase in ABA levels was independent of a loss of cell turgor or an increase in ethylene levels, both proposed triggers for rapid ABA biosynthesis. The levels of ABA in the leaf after auxin herbicide application continued to increase as plants approached death, up to >3-fold higher than in the leaves of plants that were drought stressed. We propose a new model in which synthetic auxin herbicides trigger plant death by the whole-scale, rapid, down-regulation of photosynthetic processes and an increase in ABA levels through up-regulation of NCED expression, independent of ethylene levels or a loss of cell turgor.
PMID: 32161961
Environ Microbiol , IF:4.933 , 2020 Jun , V22 (6) : P2053-2079 doi: 10.1111/1462-2920.14952
The auxin-inducible phosphate transporter AsPT5 mediates phosphate transport and is indispensable for arbuscule formation in Chinese milk vetch at moderately high phosphate supply.
State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, Lingnan Guangdong Laboratory of Modern Agriculture, Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China.; State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, China.
Phosphorus is a macronutrient that is essential for plant survival. Most land plants have evolved the ability to form a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi, which enhances phosphate (Pi) acquisition. Modulation of Pi transporter systems is the master strategy used by mycorrhizal plants to adapt to ambient Pi concentrations. However, the specific functions of PHOSPHATE TRANSPORTER 1 (PHT1) genes, which are Pi transporters that are responsive to high Pi availability, are largely unknown. Here, we report that AsPT5, an Astragalus sinicus (Chinese milk vetch) member of the PHT1 gene family, is conserved across dicotyledons and is constitutively expressed in a broad range of tissues independently of Pi supply, but is remarkably induced by indole-3-acetic acid (auxin) treatment under moderately high Pi conditions. Subcellular localization experiments indicated that AsPT5 localizes to the plasma membrane of plant cells. Using reverse genetics, we showed that AsPT5 not only mediates Pi transport and remodels root system architecture but is also essential for arbuscule formation in A. sinicus under moderately high Pi concentrations. Overall, our study provides insight into the function of AsPT5 in Pi transport, AM development and the cross-talk between Pi nutrition and auxin signalling in mycorrhizal plants.
PMID: 32079042
Ecotoxicol Environ Saf , IF:4.872 , 2020 Jun , V196 : P110498 doi: 10.1016/j.ecoenv.2020.110498
Effect of rhizospheric inoculation of isolated arsenic (As) tolerant strains on growth, As-uptake and bacterial communities in association with Adiantum capillus-veneris.
Plant Ecology and Climate Change Science, National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226001, UP, India; Department of Botany, University of Lucknow, UP, India. Electronic address: naina.marwa@gmail.com.; Division of Microbial Technology, National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226001, UP, India.; Plant Ecology and Climate Change Science, National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226001, UP, India.; Department of Botany, University of Lucknow, UP, India.; Plant Ecology and Climate Change Science, National Botanical Research Institute, Rana Pratap Marg, Lucknow, 226001, UP, India. Electronic address: nanditasingh8@yahoo.co.in.
Two arsenic (As) hyper-tolerant bacterial strains NM01 Paracoccus versutus and NM04 Aeromonas caviae were isolated from As polluted site of West Bengal, India. The strains not only possess the potential to tolerate up to 20,000 mgl(-1) As(V) and 10,000 mgl(-1) As(III) but also possess plant growth promoting (PGP) traits like phosphate solubilization, siderophore production, IAA production. Greenhouse pot experiments were conducted to assess the effect of rhizospheric inoculation of both the strains individually and in consortia in As accumulation by Adiantum capillus-veneries. It was observed that the microbial inoculation significantly (p < 0.05) increased the synthesis of thiolic compounds and thus, enhanced As accumulation with translocation factor (TF) > 1. The strains regulated endogenous phytohormone up to 90% and 77.9% increase in auxin of consortia inoculated root and shoot, respectively. Interestingly, inoculation of the isolated strains augmented rhizospheric microbial diversity which was negatively affected by heavy metal. The results of high-throughput Illumina MiSeq sequencing technique to observe the composition of the bacterial community revealed 11,536 unique bacterial operational taxonomic units (OTUs) from As + S (non-inoculated), whereas 11,884 from Consortia As + S (inoculated) rhizospheric soil samples. Inoculated soil displayed higher bacterial diversity indices (ACE and Chao 1) with the dominant bacterial phyla Proteobacteria, Actinobacteria and Firmicutes. Our results highlight the innate PGP abilities of the strains and its potential to facilitate phytoextraction by enhancing As accumulation in the shoot.
PMID: 32247957
Inorg Chem , IF:4.825 , 2020 Jun , V59 (11) : P7779-7788 doi: 10.1021/acs.inorgchem.0c00844
pH- and Time-Dependent Release of Phytohormones from Diruthenium Complexes.
Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid, Ciudad Universitaria, E-28040 Madrid, Spain.; Laboratorio de Difraccion de Rayos X de Monocristal, Servicio Interdepartamental de Investigacion, Universidad Autonoma de Madrid, E-28049 Madrid, Spain.; Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Nicolas Cabrera 1, E-28049 Madrid, Spain.
The controlled release of functionally active compounds is important in a variety of applications. Here, we have synthesized, characterized, and studied the magnetic properties of three novel metal-metal-bonded tris(formamidinato) Ru2(5+) complexes. We have used different auxin-related hormones, indole-3-acetate (IAA), 2,4-dichlorophenoxyacetate (2,4-D), and 1-naphthaleneacetate (NAA), to generate [Ru2Cl(mu-DPhF)3(mu-IAA)] (RuIAA), [Ru2Cl(mu-DPhF)3(mu-2,4-D)] (Ru2,4-D), and [Ru2Cl(mu-DPhF)3(mu-NAA)] (RuNAA) (DPhF = N,N'-diphenylformamidinate). The crystal structures of RuIAA, RuIAA.THF, Ru2,4-D.CH2Cl2, and RuNAA.0.5THF have been determined by single-crystal X-ray diffraction. To assess the releasing capacity of the bound hormone, we have employed a biological assay that relied on Arabidopsis thaliana plants expressing an auxin reporter gene and we demonstrate that the release of the phytohormones from RuIAA, Ru2,4-D, and RuNAA is pH- and time-dependent. These studies serve as a proof of concept showing the potential of these types of compounds as biological molecule carriers.
PMID: 32412249
J Mol Biol , IF:4.76 , 2020 Jun , V432 (14) : P4010-4022 doi: 10.1016/j.jmb.2020.04.007
Determinants of PB1 Domain Interactions in Auxin Response Factor ARF5 and Repressor IAA17.
Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea.; Protein Structure Research Team, Korea Basic Science Institute, 162 Yeongudanji-Ro, Ochang-Eup, Cheongju-Si, Chungcheongbuk-7Do 28119, Republic of Korea.; Protein Structure Research Team, Korea Basic Science Institute, 162 Yeongudanji-Ro, Ochang-Eup, Cheongju-Si, Chungcheongbuk-7Do 28119, Republic of Korea. Electronic address: ksryu@kbsi.re.kr.; Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea; Institute for Biomedical Sciences, Shinshu University, Minamiminowa, Nagano 399-4598, Japan. Electronic address: jysuh@snu.ac.kr.
Auxin is a plant hormone that is central to plant growth and development from embryogenesis to senescence. Auxin signaling is mediated by auxin response transcription factors (ARFs) and Aux/IAA repressors that regulate the expression of a multitude of auxin response genes. ARF and Aux/IAA proteins assemble into homomeric and heteromeric complexes via their conserved PB1 domains. Here we report the first crystal structure of the PB1 complex between ARF5 and IAA17 of Arabidopsis thaliana, which represents the transcriptionally repressed state at low auxin levels. The PB1 domains assemble in a head-to-tail manner with a backbone arrangement similar to that of the ARF5:ARF5 PB1 complex. The ARF5:IAA17 complex, however, reveals distinct points of contact that promote the ARF5:IAA17 interaction over the ARF5:ARF5 interaction. Specifically, surface charges at the interface form salt-bridges that distinguish the homomeric and heteromeric complexes, revealing common and specific interfaces between transcriptionally repressed and derepressed states. Further, the salt-bridges can be reconfigured to switch the affinity between homomeric and heteromeric complexes in an incremental manner. The complex structure combined with quantitative binding analyses would be essential for deciphering the PB1 interaction code underlying the transcriptional regulation of auxin signaling.
PMID: 32305460
Int J Mol Sci , IF:4.556 , 2020 Jun , V21 (13) doi: 10.3390/ijms21134593
Crosstalk between Hydrogen Sulfide and Other Signal Molecules Regulates Plant Growth and Development.
Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
Hydrogen sulfide (H2S), once recognized only as a poisonous gas, is now considered the third endogenous gaseous transmitter, along with nitric oxide (NO) and carbon monoxide (CO). Multiple lines of emerging evidence suggest that H2S plays positive roles in plant growth and development when at appropriate concentrations, including seed germination, root development, photosynthesis, stomatal movement, and organ abscission under both normal and stress conditions. H2S influences these processes by altering gene expression and enzyme activities, as well as regulating the contents of some secondary metabolites. In its regulatory roles, H2S always interacts with either plant hormones, other gasotransmitters, or ionic signals, such as abscisic acid (ABA), ethylene, auxin, CO, NO, and Ca(2+). Remarkably, H2S also contributes to the post-translational modification of proteins to affect protein activities, structures, and sub-cellular localization. Here, we review the functions of H2S at different stages of plant development, focusing on the S-sulfhydration of proteins mediated by H2S and the crosstalk between H2S and other signaling molecules.
PMID: 32605208
Int J Mol Sci , IF:4.556 , 2020 Jun , V21 (12) doi: 10.3390/ijms21124498
The Regulation of CIN-like TCP Transcription Factors.
State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing 100871, China.; School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China.
TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR 1 and 2 (TCP) family proteins are the plant-specific transcription factors extensively participating in diverse developmental processes by integrating external cues with internal signals. The roles of CINCINNATA (CIN)-like TCPs are conserved in control of the morphology and size of leaves, petal development, trichome formation and plant flowering. The tight regulation of CIN-like TCP activity at transcriptional and post-transcriptional levels are central for plant developmental plasticity in response to the ever-changing environmental conditions. In this review, we summarize recent progresses with regard to the function and regulation of CIN-like TCPs. CIN-like TCPs are regulated by abiotic and biotic cues including light, temperature and pathogens. They are also finely controlled by microRNA319 (miRNA319), chromatin remodeling complexes and auxin homeostasis. The protein degradation plays critical roles in tightly controlling the activity of CIN-like TCPs as well.
PMID: 32599902
Int J Mol Sci , IF:4.556 , 2020 Jun , V21 (12) doi: 10.3390/ijms21124195
From Single Cell to Plants: Mesophyll Protoplasts as a Versatile System for Investigating Plant Cell Reprogramming.
Institute of Biology II/Molecular Plant Physiology, Centre for BioSystems Analysis, BIOSS Centre for Biological Signalling Studies University of Freiburg, 79104 Freiburg, Germany.; Institute of Cell Biology and Genetic Engineering of the National Academy of Sciences of Ukraine, 03143 Kyiv, Ukraine.; Plant Cytogenetics and Molecular Biology Group, Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, 40-032 Katowice, Poland.
Plants are sessile organisms that have a remarkable developmental plasticity, which ensures their optimal adaptation to environmental stresses. Plant cell totipotency is an extreme example of such plasticity, whereby somatic cells have the potential to form plants via direct shoot organogenesis or somatic embryogenesis in response to various exogenous and/or endogenous signals. Protoplasts provide one of the most suitable systems for investigating molecular mechanisms of totipotency, because they are effectively single cell populations. In this review, we consider the current state of knowledge of the mechanisms that induce cell proliferation from individual, differentiated somatic plant cells. We highlight initial explant metabolic status, ploidy level and isolation procedure as determinants of successful cell reprogramming. We also discuss the importance of auxin signalling and its interaction with stress-regulated pathways in governing cell cycle induction and further stages of plant cell totipotency.
PMID: 32545519
J Agric Food Chem , IF:4.192 , 2020 Jun , V68 (24) : P6770-6775 doi: 10.1021/acs.jafc.0c00749
Imaging of Multiple Plant Hormones in Roots of Rice (Oryza sativa) Using Nanoparticle-Assisted Laser Desorption/Ionization Mass Spectrometry.
Department of Bioscience and Biotechnology, Fukui Prefectural University, 4-1-1 Matsuoka-Kenjojima, Eiheiji, Fukui 910-1195, Japan.; Faculty of Food and Agricultural Sciences, Fukushima University, Kanayagawa, Fukushima 960-1296, Japan.
Plant hormones can act in synergistic and antagonistic ways in response to biotic and abiotic stresses and in plant growth and development. Thus, a technique is needed to simultaneously determine the distributions and concentrations of several plant hormones. Previously, we reported that localizations of two plant hormones [cytokinin (CK) and abscisic acid (ABA)] can be simultaneously visualized in a plant tissue using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). In MALDI-MS, however, self-ionization of an organic matrix occasionally interferes with ionizations of small molecules (<500 m/z) including most plant hormones. Another technique, nanoparticle-assisted laser desorption/ionization (Nano-PALDI), can avoid matrix self-ionization using nanoparticles to assist the ionization of analytes. Here, we compared the ionization efficiencies of common plant hormones by MALDI-MS and Nano-PALDI-MS. For the comparison, we prepared a standard mix of seven plant hormones [ABA, auxin (IAA), brassinosteroid (Br), two CKs (trans-zeatin, tZ, and 6-(gamma,gamma-dimethylallylamino) purine, iP), jasmonic acid, and salicylic acid (SA)], an ethylene precursor (1-aminocyclopropane-1-carboxylic acid, ACC), and a heavy hydrogen-labeled ABA (D6-ABA). Basic MALDI-MS detected all compounds except IAA, Br, and D6-ABA, while Nano-PALDI-MS detected all nine compounds. By Nano-PALDI-MS imaging (MSI), each of the abovementioned hormones and ACC were also detected in root cross sections of rice which were incubated in the hormone mix for 2 h. In the elongation zone of untreated roots, Nano-PALDI-MSI revealed high levels of ABA and CKs in the outer part of roots and much lower levels in the stele, but Br, SA, and ACC were broadly distributed in the cross section. IAA seemed to be distributed in the epidermis, cortex, and stele. Multiple-hormone imaging using Nano-PALDI-MS has great potential for investigating the roles of hormone signaling in crop development and stress responses.
PMID: 32437141
Physiol Plant , IF:4.148 , 2020 Jun doi: 10.1111/ppl.13158
Gibberellins and auxin regulate soybean hypocotyl elongation under low light and high-temperature interaction.
Sichuan Engineering Research Center for Crop Strip Intercropping System, Sichuan Agricultural University, Chengdu, 611130, China.; Key Laboratory of Crop Ecophysiology and Farming System in Southwest China (Ministry of Agriculture), Sichuan Agricultural University, Chengdu, 611130, China.; College of Agronomy, Sichuan Agricultural University, Chengdu, 611130, China.
Soybean is an important oilseed crop grown globally. However, two examples of environmental stresses that drastically regulate soybean growth are low light and high temperature. Emerging evidence suggests a possible interconnection between these two environmental stimuli. Low light and high temperature as individual factors have been reported to regulate plant hypocotyl elongation. However, their interactive signal effect on soybean growth and development remains largely unclear. Here, we report that gibberellins (GAs) and auxin are required for soybean hypocotyl elongation under low light and high temperature interaction. Our analysis indicated that low light and high temperature interaction enhanced the regulation of soybean hypocotyl elongation and that the endogenous GA3 , GA7 , indole-3-acetic acid (IAA) and indole-3-pyruvate (IPA) contents significantly increased. Again, analysis of the effect of exogenous phytohormones and biosynthesis inhibitors treatments showed that exogenous GA, IAA, and paclobutrazol (PAC), 2, 3, 5,-triiodobenzoic acid (TIBA) treatments significantly regulated soybean seedlings growth under low light and high temperature interaction. Further qRT-PCR analysis showed that the expression level of GA biosynthesis pathway genes (GmGA3ox1, GmGA3ox2, and GmGA3) and auxin biosynthesis pathway genes (GmYUCCA3, GmYUCCA5, and GmYUCCA7) significantly increased under (i) low light and high temperature interaction and (ii) exogenous GA and IAA treatments. Altogether, these observations support the hypothesis that gibberellins and auxin regulate soybean hypocotyl elongation under low light and high temperature stress interaction. This article is protected by copyright. All rights reserved.
PMID: 32588443
Physiol Plant , IF:4.148 , 2020 Jun , V169 (2) : P214-227 doi: 10.1111/ppl.13063
WEG1, which encodes a cell wall hydroxyproline-rich glycoprotein, is essential for parental root elongation controlling lateral root formation in rice.
Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi, 464-8601, Japan.; Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan.; International Center for Research and Education in Agriculture, Nagoya University, Nagoya, Aichi, 464-8601, Japan.; Department of Horticulture, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya.; Kihara Institute for Biological Research, Yokohama City University, Yokohama, Kanagawa, 244-0813, Japan.; PREST, JST, Kawaguchi, Saitama, 332-0012, Japan.
Lateral roots (LRs) determine the overall root system architecture, thus enabling plants to efficiently explore their underground environment for water and nutrients. However, the mechanisms regulating LR development are poorly understood in monocotyledonous plants. We characterized a rice mutant, wavy root elongation growth 1 (weg1), that produced higher number of long and thick LRs (L-type LRs) formed from the curvatures of its wavy parental roots caused by asymmetric cell growth in the elongation zone. Consistent with this phenotype, was the expression of the WEG1 gene, which encodes a putative member of the hydroxyproline-rich glycoprotein family that regulates cell wall extensibility, in the root elongation zone. The asymmetric elongation growth in roots is well known to be regulated by auxin, but we found that the distribution of auxin at the apical region of the mutant and the wild-type roots was symmetric suggesting that the wavy root phenotype in rice is independent of auxin. However, the accumulation of auxin at the convex side of the curvatures, the site of L-type LR formation, suggested that auxin likely induced the formation of L-type LRs. This was supported by the need of a high amount of exogenous auxin to induce the formation of L-type LRs. These results suggest that the MNU-induced weg1 mutated gene regulates the auxin-independent parental root elongation that controls the number of likely auxin-induced L-type LRs, thus reflecting its importance in improving rice root architecture.
PMID: 31925781
Plant Cell Physiol , IF:4.062 , 2020 Jun doi: 10.1093/pcp/pcaa086
OsHDA710-mediated Histone Deacetylation Regulates Callus Formation of Rice Mature Embryo.
Institute of Genetic and Regenerative Biology, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, College of Life Sciences, Zhejiang University, Hangzhou, China.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, China.; Key Laboratory of Plant Nutrition and Fertilizers, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, China.; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, China.
Histone deacetylases (HDACs) play important roles in the regulation of eukaryotic gene expression. The role of HDACs in specialized transcriptional regulation and biological processes is poorly understood. In this study, we evaluated the global expression patterns of genes related to epigenetic modifications during callus initiation in rice. We found that the repression of HDAC activity by trichostatin A (TSA) or by OsHDA710 mutation (hda710) results in impaired callus formation of rice mature embryo and increased global histone H3 acetylation levels. The HDAC inhibition decreased auxin response and cell proliferation in callus formation. Meanwhile, the transcriptional repressors OsARF18 and OsARF22 were upregulated in the callus of hda710. The ChIP-qPCR analysis demonstrated that the callus of hda710 exhibited enhanced histone H3 acetylation levels at the chromatin regions of OsARF18 and OsARF22. Furthermore, we found that OsARF18 and OsARF22 were regulated through the OsHDA710 recruitment to their target loci. Additionally, overexpression of OsARF18 decreased the transcription of downstream genes PLT1 and PLT2, and inhibited callus formation of mature embryo. These results demonstrate that OsHDA710 regulates callus formation by suppressing repressive OsARFs via histone deacetylation during callus formation of rice mature embryo. This indicates that OsHDA710-mediated histone deacetylation is an epigenetic regulation pathway for maintaining auxin response during cell dedifferentiation.
PMID: 32592489
Plant Cell Physiol , IF:4.062 , 2020 Jun doi: 10.1093/pcp/pcaa089
The Role of Auxin in Late Stamen Development.
IBPM-CNR c/o Dip. Biologia e Biotecnologie, Sapienza Universita di Roma, Italy.
PMID: 32592488
Plant Cell Physiol , IF:4.062 , 2020 Jun doi: 10.1093/pcp/pcaa088
Letter to the Editor: Author Response - The role of auxin in late stamen development.
Max Planck Institute for Plant Breeding Research, Carl-von-Linne-Weg 10, 50829 Cologne, Germany.
PMID: 32592487
Plant Cell Physiol , IF:4.062 , 2020 Jun doi: 10.1093/pcp/pcaa081
The N-Terminal Acetyltransferase Naa50 Regulates Arabidopsis Growth and Osmotic Stress Response.
College of Life Sciences, Shanxi Normal University, Linfen, Shanxi, China.; College of Life Sciences, Capital Normal University, Beijing, China.; Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
N-terminal acetylation is one of the most common protein modifications in eukaryotes. The function of Naa50, the catalytic subunit of the evolutionarily conserved N-terminal acetyltransferase E complex, has not been reported in Arabidopsis. In this study, we found that a loss of Naa50 resulted in a pleiotropic phenotype that included dwarfism and sterility, premature leaf senescence, and a shortened primary root. Further analysis revealed that root cell patterning and various root cell properties were severely impaired in naa50 mutant plants. Moreover, defects in auxin distribution were observed due to the mislocalization of PIN auxin transporters. In contrast to its homologs in yeast and animals, Naa50 showed no co-immunoprecipitation with any subunit of the N-terminal acetyltransferase A complex. Moreover, plants lacking Naa50 displayed hypersensitive to abscisic acid and osmotic stress. Therefore, our results suggest that protein N-terminal acetylation catalyzed by Naa50 plays an essential role in Arabidopsis growth and osmotic stress responses.
PMID: 32544241
Plant Cell Physiol , IF:4.062 , 2020 Jun , V61 (6) : P1134-1143 doi: 10.1093/pcp/pcaa038
Early Establishment of Photosynthesis and Auxin Biosynthesis Plays a Key Role in Early Biomass Heterosis in Brassica napus (Canola) Hybrids.
Agriculture and Food, Commonwealth Scientific and Industrial Research Organization, Canberra, Australian Capital Territory 2600, Australia.; School of Life Sciences, Faculty of Science, University of Technology, Sydney, New South Wales 2007, Australia.
Heterosis or hybrid vigor has been used widely for more than a decade in Canola (Brassica napus) production. Canola hybrids show heterosis in a variety of traits compared to parents, including increased biomass at the early stages of seedling establishment, which is a critical developmental step that impacts future plant growth and seed yield. In this study, we examined transcriptomes of two parental lines, Garnet (Gar) and NX0052 (0052), and their reciprocal hybrids, Gar/0052, at 4 and 8 days after sowing (DAS). In hybrids, early seedling biomass heterosis is correlated with earlier expression of genes in photosynthesis pathways relative to parents. The hybrids also showed early expression of genes in the auxin biosynthesis pathway, consistent with the higher auxin concentrations detected in hybrid seedlings at 4 DAS. Auxin is a key phytohormone that regulates plant development promoting cell expansion and cell proliferation. Consistent with the increased levels of auxin, hybrids have larger and more palisade cells than the parents at the same time point. We propose a possible mechanism of early biomass heterosis through the early establishment of photosynthesis and auxin biosynthesis, providing insights into how transcriptional changes in hybrids are translated into phenotypical heterosis. This finding could be utilized in future Canola breeding to identify hybrid combinations with the superior early seedling establishment and strong levels of hybrid vigor in later plant development.
PMID: 32215572
Sci Rep , IF:3.998 , 2020 Jun , V10 (1) : P10294 doi: 10.1038/s41598-020-67153-9
Complete genome sequence of sixteen plant growth promoting Streptomyces strains.
International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India. s.gopalakrishnan@cgiar.org.; International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India. vivek22@gmail.com.; School of Life Sciences, University of Hyderabad, Hyderabad, India. vivek22@gmail.com.; International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India.; International Crops Research Institute for the Semi-Arid Tropics, Hyderabad, India. r.k.varshney@cgiar.org.
The genome sequences of 16 Streptomyces strains, showing potential for plant growth-promotion (PGP) activities in rice, sorghum, chickpea and pigeonpea, isolated from herbal vermicompost, have been decoded. The genome assemblies of the 16 Streptomyces strains ranged from 6.8 Mb to 8.31 Mb, with a GC content of 72 to 73%. The extent of sequence similarity (in terms of shared ortholog) in 16 Streptomyces strains showed 70 to 85% common genes to the closest publicly available Streptomyces genomes. It was possible to identify ~1,850 molecular functions across these 16 strains, of which close to 50% were conserved across the genomes of Streptomyces strains, whereas, ~10% were strain specific and the rest were present in various combinations. Genome assemblies of the 16 Streptomyces strains have also provided genes involved in key pathways related to PGP and biocontrol traits such as siderophores, auxin, hydrocyanic acid, chitinase and cellulase. Further, the genome assemblies provided better understanding of genetic similarity among target strains and with the publically available Streptomyces strains.
PMID: 32581303
Sci Rep , IF:3.998 , 2020 Jun , V10 (1) : P9171 doi: 10.1038/s41598-020-66172-w
Engineering and use of proteinoid polymers and nanocapsules containing agrochemicals.
The Institute of Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel.; Gilat Research Center, Agricultural Research Organization, Mobile Post Negev 2, Gilat, 8531100, Israel.; The Institute of Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan, 5290002, Israel. shlomo.margel@biu.ac.il.; Gilat Research Center, Agricultural Research Organization, Mobile Post Negev 2, Gilat, 8531100, Israel. lironk@volcani.agri.gov.il.
To address global challenges such as population growth and climate change, introduction of new technologies and innovations in agriculture are paramount. Polymer-based formulations of agrochemicals have received much attention in recent years, and there is strong motivation to develop agrochemicals that are not harmful to the environment. Proteinoid polymers are produced by thermal step-growth polymerization of natural and unnatural amino acids. Under suitable gentle conditions, the proteinoid polymers may self-assemble to form nano-sized hollow proteinoid nanoparticles (NPs) of a relatively narrow size distribution. Agrochemical molecules may be encapsulated within these hollow proteinoid NPs, integrated in the crude proteinoid shell, or bound covalently/physically to the NP surface. In the present manuscript we prepared and characterized four model proteinoid polymers and NPs: P(KEf), P(KF), P(EWH-PLLA) and P(KWH-PLLA), where Ef denotes the unnatural herbicidal amino acid glufosinate. The NPs were fluorescently labeled and loaded with agrochemicals such as the plant hormone auxin. In addition, the NP surface was hydrophobized by covalent conjugation of dodecyl aldehyde via its surface primary amine groups. Following treatment of the plants with the different fluorescent-labeled NPs, fluorescent microscopic techniques enabled to localize the NPs and observe the accumulation in the plant's vascular system. Next, using genetically modified plants, which express fluorescent protein and are responsive to the level of auxin, we demonstrated the possibility to deliver encapsulated agrochemicals into cells. We also illustrated that the proteinoid NPs are non-toxic to human umbilical vein endothelial cells, and apart from P(KEf) also to lettuce plants.
PMID: 32514082
Sci Rep , IF:3.998 , 2020 Jun , V10 (1) : P9082 doi: 10.1038/s41598-020-65909-x
Transcriptome Analysis by RNA-Seq Reveals Genes Related to Plant Height in Two Sets of Parent-hybrid Combinations in Easter lily (Lilium longiflorum).
Department of Horticulture, Sunchon National University, 255, Jungang-ro, Suncheon, Jeonnam, 57922, Republic of Korea.; Department of Horticulture, Patuakhali Science and Technology University, Dumki, Patuakhali, 8602, Bangladesh.; Department of Genetics and Plant Breeding, Bangladesh Agricultural University, Mymensingh, 2202, Bangladesh.; Department of Fisheries Science, Chonnam National University, 50, Daehak-ro, Yeosu, Jeonnam, 59626, Republic of Korea.; Department of Aquaculture, Patuakhali Science and Technology University, Dumki, Patuakhali, 8602, Bangladesh.; Department of Floriculture, Korea National College of Agriculture and Fisheries, 1515, Kongjwipatjwi-ro, Wansan-gu, Jeonju-si, Jeollabuk-do, 54874, Republic of Korea.; Department of Horticulture, Sunchon National University, 255, Jungang-ro, Suncheon, Jeonnam, 57922, Republic of Korea. nis@sunchon.ac.kr.
In this study, two different hybrids of Easter lily (Lilium longiflorum), obtained from two cross combinations, along with their four parents were sequenced by high-throughput RNA-sequencing (RNA-Seq) to find out differentially expressed gene in parent-hybrid combinations. The leaf mRNA profiles of two hybrids and their four parents were RNA-sequenced with a view to identify the potential candidate genes related to plant height heterosis. In both cross combinations, based to morphological traits mid-parent heterosis (MPH) was higher than high-parent heterosis (HPH) for plant height, leaf length, and number of flowers whereas HPH was higher than MPH for flowering time. A total of 4,327 differentially expressed genes (DEGs) were identified through RNA-Seq between the hybrids and their parents based on fold changes (FC) >/= 2 for up- and
PMID: 32494055
Sci Rep , IF:3.998 , 2020 Jun , V10 (1) : P8860 doi: 10.1038/s41598-020-65734-2
Duplication and divergence: New insights into AXR1 and AXL functions in DNA repair and meiosis.
Departamento de Genetica, Fisiologia y Microbiologia. Facultad de Biologia, Universidad Complutense de Madrid, Madrid, 28040, Spain.; Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.; Departamento de Genetica, Fisiologia y Microbiologia. Facultad de Biologia, Universidad Complutense de Madrid, Madrid, 28040, Spain. pradillo@bio.ucm.es.
Rubylation is a conserved regulatory pathway similar to ubiquitination and essential in the response to the plant hormone auxin. In Arabidopsis thaliana, AUXIN RESISTANT1 (AXR1) functions as the E1-ligase in the rubylation pathway. The gene AXR1-LIKE (AXL), generated by a relatively recent duplication event, can partially replace AXR1 in this pathway. We have analysed mutants deficient for both proteins and complementation lines (with the AXR1 promoter and either AXR1 or AXL coding sequences) to further study the extent of functional redundancy between both genes regarding two processes: meiosis and DNA repair. Here we report that whereas AXR1 is essential to ensure the obligatory chiasma, AXL seems to be dispensable during meiosis, although its absence slightly alters chiasma distribution. In addition, expression of key DNA repair and meiotic genes is altered when either AXR1 or AXL are absent. Furthermore, our results support a significant role for both genes in DNA repair that was not previously described. These findings highlight that AXR1 and AXL show a functional divergence in relation to their involvement in homologous recombination, exemplifying a duplicate retention model in which one copy tends to have more sub-functions than its paralog.
PMID: 32483285
Genes (Basel) , IF:3.759 , 2020 Jun , V11 (6) doi: 10.3390/genes11060655
Transcriptional Basis for Differential Thermosensitivity of Seedlings of Various Tomato Genotypes.
Department of Biosciences, Molecular Cell Biology of Plants, Goethe University, D-60438 Frankfurt am Main, Germany.; Buchmann Institute for Molecular Life Sciences, Goethe University, D-60438 Frankfurt am Main, Germany.; Frankfurt Institute of Advanced Studies (FIAS), D-60438 Frankfurt am Main, Germany.; Institute of Bioinformatics, University Medicine Greifswald, D-17475 Greifswald, Germany.
Transcriptional reprograming after the exposure of plants to elevated temperatures is a hallmark of stress response which is required for the manifestation of thermotolerance. Central transcription factors regulate the stress survival and recovery mechanisms and many of the core responses controlled by these factors are well described. In turn, pathways and specific genes contributing to variations in the thermotolerance capacity even among closely related plant genotypes are not well defined. A seedling-based assay was developed to directly compare the growth and transcriptome response to heat stress in four tomato genotypes with contrasting thermotolerance. The conserved and the genotype-specific alterations of mRNA abundance in response to heat stress were monitored after exposure to three different temperatures. The transcripts of the majority of genes behave similarly in all genotypes, including the majority of heat stress transcription factors and heat shock proteins, but also genes involved in photosynthesis and mitochondrial ATP production. In turn, genes involved in hormone and RNA-based regulation, such as auxin- and ethylene-related genes, or transcription factors like HsfA6b, show a differential regulation that associates with the thermotolerance pattern. Our results provide an inventory of genes likely involved in core and genotype-dependent heat stress response mechanisms with putative role in thermotolerance in tomato seedlings.
PMID: 32560080
Genes (Basel) , IF:3.759 , 2020 Jun , V11 (6) doi: 10.3390/genes11060633
Nitrate Signaling, Functions, and Regulation of Root System Architecture: Insights from Arabidopsis thaliana.
Key Laboratory of Tobacco Biology and Processing, Ministry of Agriculture, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.; Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China.; Key Laboratory for Tobacco Gene Resources, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, China.
Root system architecture (RSA) is required for the acquisition of water and mineral nutrients from the soil. One of the essential nutrients, nitrate (NO3(-)), is sensed and transported by nitrate transporters NRT1.1 and NRT2.1 in the plants. Nitrate transporter 1.1 (NRT1.1) is a dual-affinity nitrate transporter phosphorylated at the T101 residue by calcineurin B-like interacting protein kinase (CIPKs); it also regulates the expression of other key nitrate assimilatory genes. The differential phosphorylation (phosphorylation and dephosphorylation) strategies and underlying Ca(2+) signaling mechanism of NRT1.1 stimulate lateral root growth by activating the auxin transport activity and Ca(2+)-ANR1 signaling at the plasma membrane and the endosomes, respectively. NO3(-) additionally functions as a signal molecule that forms a signaling system, which consists of a vast array of transcription factors that control root system architecture that either stimulate or inhibit lateral and primary root development in response to localized and high nitrate (NO3(-)), respectively. This review elucidates the so-far identified nitrate transporters, nitrate sensing, signal transduction, and the key roles of nitrate transporters and its downstream transcriptional regulatory network in the primary and lateral root development in Arabidopsis thaliana under stress conditions.
PMID: 32526869
Plant Physiol Biochem , IF:3.72 , 2020 Jun , V151 : P378-390 doi: 10.1016/j.plaphy.2020.03.047
A natural indole alkaloid, norharmane, affects PIN expression patterns and compromises root growth in Arabidopsis thaliana.
Department of Plant Biology and Soil Science, Faculty of Biology, University of Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain; CITACA, Agri-Food Research and Transfer Cluster, Campus da Auga, University of Vigo, Ourense, Spain. Electronic address: davidlopez@uvigo.es.; Department of Plant Biology and Soil Science, Faculty of Biology, University of Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain; CITACA, Agri-Food Research and Transfer Cluster, Campus da Auga, University of Vigo, Ourense, Spain. Electronic address: aitanacostasgil@gmail.com.; Department of Plant Biology and Soil Science, Faculty of Biology, University of Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain; CITACA, Agri-Food Research and Transfer Cluster, Campus da Auga, University of Vigo, Ourense, Spain. Electronic address: mreigosa@uvigo.es.; Department of Plant Biology and Soil Science, Faculty of Biology, University of Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain; Dipartimento di AGRARIA, Universita Mediterranea di Reggio Calabria, Feo di Vito, I-89124, Reggio Calabria, Italy. Electronic address: fabrizio.araniti@unirc.it.; Department of Plant Biology and Soil Science, Faculty of Biology, University of Vigo, Campus Lagoas-Marcosende s/n, 36310, Vigo, Spain; CITACA, Agri-Food Research and Transfer Cluster, Campus da Auga, University of Vigo, Ourense, Spain. Electronic address: adela@uvigo.es.
Norharmane is an indole alkaloid that can be found in several terrestrial plants, as well as in some dinoflagellates and cyanobacteria. The aim of this study was to focus on the way this metabolite impacts the plant metabolism of the model species Arabidopsis thaliana. This metabolite caused increase of secondary and adventitious roots, as well as torsion, toxic effects, and a decrease in root length. Moreover, norharmane altered the cellular arrangement, resulting in unfinished cell walls, decreased auxin content and inhibited PIN proteins activity. All the alterations suggest that norharmane alters polar auxin transport by inhibiting PIN2, PIN3 and PIN7 transport proteins, thus causing a significant inhibitory effect on the growth of A. thaliana seedlings.
PMID: 32278957
Plant Physiol Biochem , IF:3.72 , 2020 Jun , V151 : P124-131 doi: 10.1016/j.plaphy.2020.03.016
Role of ethylene crosstalk in seed germination and early seedling development: A review.
College of Forestry, Henan University of Science and Technology, 263 Kaiyuan Avenue, Luoyang, 471023, PR China. Electronic address: ahammed@haust.edu.cn.; Crop Research Unit (Genetics and Plant Breeding), Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, 741252, India.; Department of Agricultural Biotechnology, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, 741252, India.; Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, Jiangxi Agricultural University, Nanchang, 330045, China.; Key Laboratory of Tea Quality and Safety Control, Ministry of Agriculture, Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 310008, PR China. Electronic address: lixin@tricaas.com.
Seed germination and early seedling development are two critical phases in plant lifecycle that largely determine crop yield. Phytohormones play an essential role in governing these developmental processes; of these, ethylene (ET; C2H4), the smallest gaseous hormone, plays a major role via crosstalk with other hormones. Typically, the mechanism of hormone (for instance, auxin, cytokinins, ET, and gibberellins) action is determined by cellular context, revealing either synergistic or antagonistic relations. Significant progress has been made, so far, on unveiling ET crosstalk with other hormones and environmental signals, such as light. In particular, stimulatory and inhibitory effects of ET on hypocotyl growth in light and dark, respectively, and its interaction with other hormones provide an ideal model to study the growth-regulatory pathways. In this review, we aim at exploring the mechanisms of multifarious phenomena that occur via ET crosstalk during the germination of seeds (overcoming dormancy), and all through the development of seedlings. Understanding the remarkably complex mechanism of ET crosstalk that emerges from the interaction between hormones and other molecular players to modulate plant growth, remains a challenge in plant developmental biology.
PMID: 32220785
Plant Physiol Biochem , IF:3.72 , 2020 Jun , V151 : P69-76 doi: 10.1016/j.plaphy.2020.03.013
The CmbZIP1 transcription factor of chrysanthemum negatively regulates shoot branching.
Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China. Electronic address: yuancunquan@163.com.; Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China. Electronic address: tian.5.shi@163.com.; Department of Ornamental Horticulture, China Agricultural University, Beijing, 100193, China. Electronic address: zhaolj5073@163.com.
The basic region/leucine zipper (bZIP) transcription factors play key roles in regulating diverse biological processes in plants. However, their participation in shoot branching has been rarely reported. Here, we isolated a CmbZIP1 transcription factor gene, a member of the bZIP family, from chrysanthemum. Subcellular localization analysis indicated that CmbZIP1 is a nuclear protein. Tissue-specific expression analysis indicated that CmbZIP1 was principally expressed in apical bud and axillary bud. Expression patterns analysis results showed that CmbZIP1 expression was suppressed in axillary buds in response to decapitation but increased in response to shade. Overexpression of CmbZIP1 in Arabidopsis inhibits its shoot branching. In addition, expression of auxin efflux protein PIN-FORMED 1 (PIN1) and auxin signaling components AUXIN RESISTANT 1/3 (AXR1, AXR3) were significantly up-regulated in overexpressing plants in comparison with wild type plants. Moreover, the transcript expression of BRANCHED 2 (AtBRC2) was also significantly up-regulated in overexpressing plants compared with the wild type. Altogether, these results suggest important and negative roles of CmbZIP1 in shoot branching. Our study extends the understanding of the function of bZIP transcription factors in plants and provides valuable gene resources for improving the architectural traits of ornamental plants.
PMID: 32200192
Mol Plant Microbe Interact , IF:3.696 , 2020 Jun : PMPMI02200047R doi: 10.1094/MPMI-02-20-0047-R
Dual Role of Auxin in Regulating Plant Defense and Bacterial Virulence Gene Expression During Pseudomonas syringae PtoDC3000 Pathogenesis.
Department of Biology, Washington University, St. Louis, MO, U.S.A.; Division of Biological Sciences, Section of Cell & Developmental Biology, University California San Diego, San Diego, CA, U.S.A.
Modification of host hormone biology is a common strategy used by plant pathogens to promote disease. For example, the bacterial pathogen strain Pseudomonas syringae DC3000 (PtoDC3000) produces the plant hormone auxin (indole-3-acetic acid [IAA]) to promote PtoDC3000 growth in plant tissue. Previous studies suggest that auxin may promote PtoDC3000 pathogenesis through multiple mechanisms, including both suppression of salicylic acid (SA)-mediated host defenses and via an unknown mechanism that appears to be independent of SA. To test if host auxin signaling is important during pathogenesis, we took advantage of Arabidopsis thaliana lines impaired in either auxin signaling or perception. We found that disruption of auxin signaling in plants expressing an inducible dominant axr2-1 mutation resulted in decreased bacterial growth and that this phenotype was suppressed by introducing the sid2-2 mutation, which impairs SA synthesis. Thus, host auxin signaling is required for normal susceptibility to PtoDC3000 and is involved in suppressing SA-mediated defenses. Unexpectedly, tir1 afb1 afb4 afb5 quadruple-mutant plants lacking four of the six known auxin coreceptors that exhibit decreased auxin perception, supported increased levels of bacterial growth. This mutant exhibited elevated IAA levels and reduced SA-mediated defenses, providing additional evidence that auxin promotes disease by suppressing host defense. We also investigated the hypothesis that IAA promotes PtoDC3000 virulence through a direct effect on the pathogen and found that IAA modulates expression of virulence genes, both in culture and in planta. Thus, in addition to suppressing host defenses, IAA acts as a microbial signaling molecule that regulates bacterial virulence gene expression.
PMID: 32407150
Plant Sci , IF:3.591 , 2020 Jun , V295 : P110268 doi: 10.1016/j.plantsci.2019.110268
Impact of overexpression of 9-cis-epoxycarotenoid dioxygenase on growth and gene expression under salinity stress.
Department of Plant Nutrition, CEBAS-CSIC, Murcia, Spain. Electronic address: cmandujar@cebas.csic.es.; Department of Plant Nutrition, CEBAS-CSIC, Murcia, Spain.; Instituto de Bioingenieria, Universidad Miguel Hernandez, Elche, Alicante, Spain.; The Lancaster Environment Centre, Lancaster University, Lancaster, UK.; Cranfield Soil and AgriFood Institute, Cranfield University, Bedfordshire, UK.
To better understand abscisic acid (ABA)'s role in the salinity response of tomato (Solanum lycopersicum L.), two independent transgenic lines, sp5 and sp12, constitutively overexpressing the LeNCED1 gene (encoding 9-cis-epoxycarotenoid dioxygenase, a key enzyme in ABA biosynthesis) and the wild type (WT) cv. Ailsa Craig, were cultivated hydroponically with or without the addition of 100mM NaCl. Independent of salinity, LeNCED1 overexpression (OE) increased ABA concentration in leaves and xylem sap, and salinity interacted with the LeNCED1 transgene to enhance ABA accumulation in xylem sap and roots. Under control conditions, LeNCED1 OE limited root and shoot biomass accumulation, which was correlated with decreased leaf gas exchange. In salinized plants, LeNCED1 OE reduced the percentage loss in shoot and root biomass accumulation, leading to a greater total root length than WT. Root qPCR analysis of the sp12 line under control conditions revealed upregulated genes related to ABA, jasmonic acid and ethylene synthesis and signalling, gibberellin and auxin homeostasis and osmoregulation processes. Under salinity, LeNCED1 OE prevented the induction of genes involved in ABA metabolism and GA and auxin deactivation that occurred in WT, but the induction of ABA signalling and stress-adaptive genes was maintained. Thus, complex changes in phytohormone and stress-related gene expression are associated with constitutive upregulation of a single ABA biosynthesis gene, alleviating salinity-dependent growth limitation.
PMID: 32534608
Planta , IF:3.39 , 2020 Jun , V252 (1) : P2 doi: 10.1007/s00425-020-03409-y
Spatial and developmental synthesis of endogenous sesquiterpene lactones supports function in growth regulation of sunflower.
Institute of Biology, University of Hohenheim, Garbenstrasse 30, 70593, Stuttgart, Germany. O.Spring@uni-hohenheim.de.; Institute of Biology, University of Hohenheim, Garbenstrasse 30, 70593, Stuttgart, Germany.
MAIN CONCLUSION: Tissue-specific occurrence and formation of endogenous sesquiterpene lactones has been assessed and suggests physiological function as antagonists of auxin-induced plant growth in sunflower. Sunflower, Helianthus annuus, accumulate high concentrations of bioactive sesquiterpene lactones (STL) in glandular trichomes, but in addition, structurally different STL occur in only trace amounts in the inner tissues. The spatial and temporal production of these endogenous STL during early phases of plant development is widely unknown and their physiological function as putative natural growth regulators is yet speculative. By means of HPLC and MS analysis it was shown that costunolide, dehydrocostuslactone, 8-epixanthatin and tomentosin are already present in dry seeds and can be extracted in low amounts from cotyledons, hypocotyls and roots of seedlings during the first days after germination. Semi-quantitative and RT-qPCR experiments with genes of the key enzymes of two independent routes of the endogenous STL biosynthesis confirmed the early and individual expression in these organs and revealed a gradual down regulation during the first 72-96 h after germination. Light irradiation of the plants led to a fast, but transient increase of STL in parts of the hypocotyl which correlated with growth retardation of the stem. One-sided external application of costunolide on hypocotyls conferred reduced growth of the treated side, thus resulting in the curving of the stem towards the side of the application. This indicates the inhibiting effects of STL on plant growth. The putative function of endogenous STL in sunflower as antagonists of auxin in growth processes is discussed.
PMID: 32504343
Molecules , IF:3.267 , 2020 Jun , V25 (12) doi: 10.3390/molecules25122759
Effect of Growth Regulators on Stevia rebaudiana Bertoni Callus Genesis and Influence of Auxin and Proline to Steviol Glycosides, Phenols, Flavonoids Accumulation, and Antioxidant Activity In Vitro.
Institute of Biology and Plant Biotechnology, Agriculture Academy, Vytautas Magnus University, Donelaicio str. 58, 44248 Kaunas, Lithuania.
Stevia is a plant containing many active compounds, but usually propagated by stem cuttings because of low seed-yield-germination ability. The aim of this study was to investigate the impact of plant-growth regulators on stevia callus induction and growth from somatic tissue, as well as to determine the effect alpha-naphthalene acetic acid (NAA) and proline (PRO) on the amount of stevioside, rebaudioside A, phenols, flavonoids, and antioxidant activity. Stem and leaf segments were inoculated on a Murashige and Skoog (MS) medium supplemented with different concentrations of NAA and 6-benzylaminopurine (BAP) for callus genesis. The amount of steviol glycosides (SGs) was evaluated using high-performance liquid chromatography (HPLC), and the amounts of total phenols, flavonoids, and antioxidant activity by spectrophotometric methods. The highest callus-induction frequency and callus-mass increase were obtained from the leaf explants in MS medium supplemented with 2.0 muM NAA. The highest amount of SGs, phenols, and flavonoids, and stronger antioxidant activity were determined in the cellular compounds of callus from leaf explant. PRO reduced the amount of SGs and flavonoids. The significantly highest amount of total phenolic compounds was obtained in the callus from leaf explants in the medium supplemented with 2.0 microM NAA and 2.0 microM PRO.
PMID: 32549269
Phytopathology , IF:3.234 , 2020 Jun doi: 10.1094/PHYTO-02-20-0046-R
Auxin profiling and GmPIN expression in Phytophthora sojae-soybean root interactions.
The Ohio State University, Plant Pathology, Wooster, Ohio, United States; anna.stasko@ndsu.edu.; The Ohio State University, Plant Pathology, Wooster, Ohio, United States; batnini.2@osu.edu.; The Ohio State University, Plant Pathology, Wooster, Ohio, United States; bolanos-carriel.1@osu.edu.; The Ohio State University, 2647, Horticulture and Crop Science, Wooster, Ohio, United States; lin.1518@osu.edu.; The Ohio State University, 2647, Horticulture and Crop Science, Wooster, Ohio, United States; lin.1418@osu.edu.; The Ohio State University, Horticulture and Crop Science, Wooster, Ohio, United States; blakeslee.19@osu.edu.; The Ohio State University, Plant Pathology, 1680 Madison Ave., Wooster, Ohio, United States, 44691; dorrance.1@osu.edu.
Auxin (indole-3-acetic acid, IAA) has been implicated as a susceptibility factor in both beneficial and pathogenic molecular plant-microbe interactions. Previous studies have identified a large number of auxin-related genes underlying quantitative disease resistance loci (QDRLs) for Phytophthora sojae. Thus, we hypothesized that auxin may be involved the P. sojae-soybean interaction. The levels of IAA and related metabolites were measured in mycelia and media supernatant as well as in mock and inoculated soybean roots in a time course assay. The expression of eleven soybean Pin-formed (GmPIN) auxin efflux transporter genes was also examined. Tryptophan, an auxin precursor, was detected in the P. sojae mycelia and media supernatant. During colonization of roots, levels of IAA and related metabolites were significantly higher in both moderately resistant Conrad and moderately susceptible Sloan inoculated roots compared to mock controls at 48 hours post inoculation (hpi) in one experiment and at 72 hpi in a second, with Sloan accumulating higher levels of the auxin catabolite IAA-Ala than Conrad. Additionally, one GmPIN at 24 hpi, one at 48 hpi, and three at 72 hpi had higher expression in inoculated compared to the mock control roots in Conrad. The ability of resistant cultivars to cope with auxin accumulation may play an important role in quantitative disease resistance. Levels of jasmonic acid (JA), another plant hormone associated with defense responses, were also higher in inoculated roots at these same time points, suggesting that JA also plays a role during the later stages of infection.
PMID: 32602813
BMC Microbiol , IF:2.989 , 2020 Jun , V20 (1) : P175 doi: 10.1186/s12866-020-01822-7
Thermotolerance effect of plant growth-promoting Bacillus cereus SA1 on soybean during heat stress.
School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea.; Natural and Medical Sciences Research Center, University of Nizwa, 616, Nizwa, Oman.; School of Applied Biosciences, Kyungpook National University, Daegu, 41566, Republic of Korea. ijlee@knu.ac.kr.
BACKGROUND: Incidences of heat stress due to the changing global climate can negatively affect the growth and yield of temperature-sensitive crops such as soybean variety, Pungsannamul. Increased temperatures decrease crop productivity by affecting biochemical, physiological, molecular, and morphological factors either individually or in combination with other abiotic stresses. The application of plant growth-promoting endophytic bacteria (PGPEB) offers an ecofriendly approach for improving agriculture crop production and counteracting the negative effects of heat stress. RESULTS: We isolated, screened and identified thermotolerant B. cereus SA1 as a bacterium that could produce biologically active metabolites, such as gibberellin, indole-3-acetic acid, and organic acids. SA1 inoculation improved the biomass, chlorophyll content, and chlorophyll fluorescence of soybean plants under normal and heat stress conditions for 5 and 10 days. Heat stress increased abscisic acid (ABA) and reduced salicylic acid (SA); however, SA1 inoculation markedly reduced ABA and increased SA. Antioxidant analysis results showed that SA1 increased the ascorbic acid peroxidase, superoxide dismutase, and glutathione contents in soybean plants. In addition, heat stress markedly decreased amino acid contents; however, they were increased with SA1 inoculation. Heat stress for 5 days increased heat shock protein (HSP) expression, and a decrease in GmHSP expression was observed after 10 days; however, SA1 inoculation augmented the heat stress response and increased HSP expression. The stress-responsive GmLAX3 and GmAKT2 were overexpressed in SA1-inoculated plants and may be associated with decreased reactive oxygen species generation, altered auxin and ABA stimuli, and enhanced potassium gradients, which are critical in plants under heat stress. CONCLUSION: The current findings suggest that B. cereus SA1 could be used as a thermotolerant bacterium for the mitigation of heat stress damage in soybean plants and could be commercialized as a biofertilizer only in case found non-pathogenic.
PMID: 32571217
Biochem Biophys Res Commun , IF:2.985 , 2020 Jun , V527 (1) : P124-130 doi: 10.1016/j.bbrc.2020.04.082
The nuclear localized RIN13 induces cell death through interacting with ARF1.
State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture, College of Life Sciences, Wuhan University, Wuhan, 430072, China.; State Key Laboratory of Cotton Biology, State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, 475004, China. Electronic address: liuwencheng@henu.edu.cn.; State Key Laboratory of Hybrid Rice, Key Laboratory for Research and Utilization of Heterosis in Indica Rice of Ministry of Agriculture, College of Life Sciences, Wuhan University, Wuhan, 430072, China. Electronic address: zygao@whu.edu.cn.
Resistance to Pseudomonas syringae pv. Maculicola 1 (RPM1) is a crucial immune receptor conferring plant enhanced resistance to pathogenic bacteria. RPM1-interacting protein 13 (RIN13) enhances RPM1-mediated disease resistance through interacting with the central domain of RPM1 in Arabidopsis, while the underlying mechanism remains elusive. Here, we report the subcellular localization and function of RIN13 using the Nicotiana benthamiana (N. benthamiana) transient expression system. Our results showed that RIN13 is exclusively localized in the nucleus, and RIN13 (231-300) fragment is responsible for its nuclear localization. Transient expression of RIN13 in N. benthamiana leaves can accelerate leaf senescence and cell death, and affect the activities of ROS-scavenging enzymes, and the C-terminus of RIN13 is crucial for its function. Furthermore, we identified a RIN13-interacting protein, Auxin Response Factor 1 (ARF1), and found that similar to RIN13, ARF1 can also promote leaf senescence and cell death. In addition, expression of RIN13 in N. benthamiana leaves can facilitate the translocation of ARF1 into the nucleus. Collectively, our study revealed a possible mechanism of RIN13 in accelerating leaf senescence and cell death by changing the subcellular localization of ARF1.
PMID: 32446355
Plants (Basel) , IF:2.762 , 2020 Jun , V9 (7) doi: 10.3390/plants9070816
Micropropagation of Alocasia longiloba Miq and Comparative Antioxidant Properties of Ethanolic Extracts of the Field-Grown Plant, In Vitro Propagated and In Vitro-Derived Callus.
Faculty of Agro-Based Industry, University Malaysia Kelantan, Jeli 17600, Kelantan, Malaysia.; Institute of Food Security and Sustainable Agriculture, University Malaysia Kelantan, Jeli 17600, Kelantan, Malaysia.; Faculty of Earth Science, University Malaysia Kelantan, Jeli 17600, Kelantan, Malaysia.; Department of Biochemistry, Yogi Vemana University, Vemanapuram, Kadapa 516003, Andhra Pradesh, India.; Department of Microbiology, Sri Venkateswara University, Tirupathi 517502, Andhra Pradesh, India.; Department of Paraclinical Science, Faculty of Veterinary Medicine, University Malaysia Kelantan, Pengkalan Chepa, 16100 Kota Bharu, Kelantan, Malaysia.
In this study, an efficient micropropagation protocol was developed for A. longiloba and the antioxidant properties of field-grown plant, in vitro-derived greenhouse-grown plant and in vitro-derived callus extracts were compared. The A. longiloba seeds tested using tetrazolium chloride salt exhibited 89% viability. Due to poor germination capacity of A. longiloba seeds, the seeds were treated with gibberellic acid (GA3) or sulfuric acid (H2SO4). The maximum seed germination of 87% was observed at 30% H2SO4 treatment after 19.00 d, whereas GA3 treatment showed maximum germination of 53% after 22 d. In vitro shoot multiplication was carried out using various types of cytokinins alone or in combination with auxin. Among them, 6-benzyl amino purine (BAP) single treatment was found to be the best hormone. The highest shoot-length (7.26 cm) and maximum number of shoots per explant (18) were recorded at 3-mg L(-1) BAP. For in vitro rooting, indole-3-acetic acid at 0.5-mg L(-1) was found to be the optimum concentration. Callus was induced using various types of auxins alone or in combinations with cytokinins. The highest percentage of callus of 91 and fresh weight of 6 g was obtained with 3-mg L(-1) IAA. The plantlets produced in the current study were subjected to acclimatization. The combination of topsoil and peat moss at 1:2 ratio was found to be the best soil media. In this study, in vitro-derived callus extract showed the highest phenolic content (538 mg GAE), followed by extracts of field-grown plant parts, i.e., fruit and petiole (504 and 300 mg GAE) while in vitro plant extract showed the lowest (98 mg GAE). Meanwhile, the highest flavonoids was recorded in petiole extract. Comparative antioxidant activity study shows, in vitro-derived callus exhibited better DPPH-radical-scavenging activity (IC50: 0.113-mg mL(-1)) whereas the extracts of petiole, fruit and in vitro plant showed 0.126-, 0.137- and 0.173-mg mL(-1), respectively. At the same time, the fruit extract showed better (IC50: 0.088-mg mL(-1)) ABTS radical scavenging activity than all extracts tested. In conclusion, the in vitro-derived callus extract could be favored for high TPC and better DPPH scavenging activity. Hence, the present study was conducted to establish an efficient micropropagation protocol and to compare the antioxidant activity of the field-grown plant, in vitro plant and in vitro derived callus extracts of A. longiloba.
PMID: 32610545
Plants (Basel) , IF:2.762 , 2020 Jun , V9 (6) doi: 10.3390/plants9060713
Transcriptome and Network Analyses of Heterostyly in Turnera subulata Provide Mechanistic Insights: Are S-Loci a Red-Light for Pistil Elongation?
School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA 99164-4236, USA.; Department of Biology, York University, 4700 Keele Street, Toronto, ON M3J1P3, Canada.
Heterostyly employs distinct hermaphroditic floral morphs to enforce outbreeding. Morphs differ structurally in stigma/anther positioning, promoting cross-pollination, and physiologically blocking self-fertilization. Heterostyly is controlled by a self-incompatibility (S)-locus of a small number of linked S-genes specific to short-styled morph genomes. Turnera possesses three S-genes, namely TsBAHD (controlling pistil characters), TsYUC6, and TsSPH1 (controlling stamen characters). Here, we compare pistil and stamen transcriptomes of floral morphs of T. subulata to investigate hypothesized S-gene function(s) and whether hormonal differences might contribute to physiological incompatibility. We then use network analyses to identify genetic networks underpinning heterostyly. We found a depletion of brassinosteroid-regulated genes in short styled (S)-morph pistils, consistent with hypothesized brassinosteroid-inactivating activity of TsBAHD. In S-morph anthers, auxin-regulated genes were enriched, consistent with hypothesized auxin biosynthesis activity of TsYUC6. Evidence was found for auxin elevation and brassinosteroid reduction in both pistils and stamens of S- relative to long styled (L)-morph flowers, consistent with reciprocal hormonal differences contributing to physiological incompatibility. Additional hormone pathways were also affected, however, suggesting S-gene activities intersect with a signaling hub. Interestingly, distinct S-genes controlling pistil length, from three species with independently evolved heterostyly, potentially intersect with phytochrome interacting factor (PIF) network hubs which mediate red/far-red light signaling. We propose that modification of the activities of PIF hubs by the S-locus could be a common theme in the evolution of heterostyly.
PMID: 32503265
Plants (Basel) , IF:2.762 , 2020 Jun , V9 (6) doi: 10.3390/plants9060705
Auxin: Hormonal Signal Required for Seed Development and Dormancy.
Departamento de Biologia Funcional (Area Fisiologia Vegetal), Facultad de Farmacia, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
The production of viable seeds is a key event in the life cycle of higher plants. Historically, abscisic acid (ABA) and gibberellin (GAs) were considered the main hormones that regulate seed formation. However, auxin has recently emerged as an essential player that modulates, in conjunction with ABA, different cellular processes involved in seed development as well as the induction, regulation and maintenance of primary dormancy (PD). This review examines and discusses the key role of auxin as a signaling molecule that coordinates seed life. The cellular machinery involved in the synthesis and transport of auxin, as well as their cellular and tissue compartmentalization, is crucial for the development of the endosperm and seed-coat. Thus, auxin is an essential compound involved in integuments development, and its transport from endosperm is regulated by AGAMOUS-LIKE62 (AGL62) whose transcript is specifically expressed in the endosperm. In addition, recent biochemical and genetic evidence supports the involvement of auxins in PD. In this process, the participation of the transcriptional regulator ABA INSENSITIVE3 (ABI3) is critical, revealing a cross-talk between auxin and ABA signaling. Future experimental aimed at advancing knowledge of the role of auxins in seed development and PD are also discussed.
PMID: 32492815
Protoplasma , IF:2.751 , 2020 Jun doi: 10.1007/s00709-020-01508-x
Transcriptional analysis reveals sodium nitroprusside affects alfalfa in response to PEG-induced osmotic stress at germination stage.
College of Life Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Lanzhou, 730070, Gansu Province, People's Republic of China.; College of Life Science and Technology, Gansu Agricultural University, No. 1 Yingmen Village, Anning District, Lanzhou, 730070, Gansu Province, People's Republic of China. weixh@gsau.edu.cn.; College of Business Administration, Kent State University, Kent, OH, USA.; College of Agronomy, Gansu Agricultural University, Lanzhou, China.
Drought is one of the most common environmental factors that affect alfalfa germination and development. Nitric oxide (NO) could mediate stress tolerance in plants. The goal of this study was to determine exogenous NO donor-mediated drought adaption molecular mechanisms during the alfalfa germination stage. In this study, physiological and transcriptome analyses were performed on 7 days of the growth period seedlings by sodium nitroprusside (SNP) and polyethylene glycol (PEG) treatment. The results showed that SNP supplementation alleviated malondialdehyde accumulation, increased levels of proline and soluble sugars, and enhanced antioxidant enzyme activity under osmotic stress conditions. RNA-Seq experiments identified 5828 genes exhibiting differential expression in seedlings treated with PEG, SNP, or SNP+PEG relative to seedlings treated with distilled water. Of these DEGs, 3235 were upregulated, and 2593 were downregulated relative to the controls. Fifteen DEGs were amplified by qRT-PCR to verify the changes in expression determined by RNA-Seq, revealing that PIF3, glnA, PLCG1, and RP-S11e exhibited enhanced expression under the SNP+PEG treatment. SNP was found to modulate redox homeostasis-related genes such as GSTs, SOD2, GPX, and RBOH, and triggered calcium signaling transduction. It also induced some key genes relating to the abscisic acid, ethylene, and auxin signaling transduction in response to PEG stress. Conversely, genes associated with secondary metabolite biosynthesis and the metabolism of starch and sucrose during osmotic stress were downregulated by SNP. These results provide new insights into SNP-mediated drought adaption mechanisms at transcriptome-wide in alfalfa and reveal key drought tolerance pathways in this species.
PMID: 32556557
Antonie Van Leeuwenhoek , IF:2.674 , 2020 Jun doi: 10.1007/s10482-020-01434-1
Isolation and characterization of plant growth-promoting rhizobacteria and their effects on the growth of Medicago sativa L. under salinity conditions.
National Engineering Research Center for Biotechnology, School of Biological and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu Road(s), Nanjing, 211816, China.; National Engineering Research Center for Biotechnology, School of Biological and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu Road(s), Nanjing, 211816, China. ngao@njtech.edu.cn.; National Engineering Research Center for Biotechnology, School of Biological and Pharmaceutical Engineering, Nanjing Tech University, No. 30, Puzhu Road(s), Nanjing, 211816, China. yinghanjie@njtech.edu.cn.
Plant growth-promoting rhizobacteria are a group of free-living bacteria that colonize plant rhizosphere and benefit plant root growth, thereby increasing host plant to cope with salinity induced stress. The aim of this study was to (1) isolate and characterize auxin-producing bacteria showing a high plant growth-promoting (PGP) potential, and (2) evaluate the PGP effects on the growth of Medicago sativa L under salinity stress (130 mM NaCl). Of thirteen isolates, Bacillus megaterium NRCB001 (NRCB001), B. subtilis subsp. subtilis NRCB002 (NRCB002) and B. subtilis NRCB003 (NRCB003) had the ability to produce auxin, which ranged from 47.53 to 154.38 mug ml(-1). The three auxin-producing bacterial strains were shown multiple PGP traits, such as producing siderophore and NH3, showing ACC deaminase activity, solubilize phosphate and potassium. Furthermore, NRCB001, NRCB002, and NRCB003 could survive in LB medium containing 1750 mM NaCl. The three auxin-producing with salinity tolerance strains were selected for further analyses. In greenhouse experiments, when inoculated with NRCB001, NRCB002 and NRCB003, dry weight of alfalfa significantly (P < 0.05) increased by 24.1%, 23.1% and 38.5% respectively, compared with those of non-inoculated control seedlings under normal growth condition. When inoculated with NRCB002 and NRCB003, dry weight of alfalfa significantly (P < 0.05) increased by 96.9 and 71.6% respectively, compared with those of non-inoculated control seedlings under 130 mM NaCl condition. Our results indicated that NRCB002 and NRCB003 having PGP traits are promising candidate strains to develop biofertilizers, especially used under salinity stress conditions.
PMID: 32564275
Funct Plant Biol , IF:2.617 , 2020 Jun doi: 10.1071/FP19107
Hydrogen-rich water promotes elongation of hypocotyls and roots in plants through mediating the level of endogenous gibberellin and auxin.
The aim of this study was to investigate effects of the hydrogen-rich water (HRW) on the vegetable growth, and explore the possibility of applying HRW for protected cultivation of vegetables. Results showed that compared with control, HRW treatment significantly promoted fresh weight, hypocotyl length and root length of mung bean seedlings. The strongest stimulation was observed for 480 muM H2 (60% of saturated HRW concentration) treatment. This concentration was used in the following experiments. The enhanced cell elongation was correlated with the changes in the level of endogenous phytohormones. In the dark-grown hypocotyls and roots of mung bean seedlings, HRW significantly increased the content of IAA and GA3. Addition of GA3 enhanced the hypocotyl elongation only. uniconazole, an inhibitor of GA3 biosynthesis, inhibited HRW-induced hypocotyl elongation, but did not affect root elongation. Exogenous application of IAA promoted HRW effects on elongation of both the hypocotyl and the root, while the IAA biosynthesis inhibitor TIBA negated the above affects. The general nature of HRW-induced growth-promoting effects was further confirmed in experiments involving cucumber and radish seedlings. Taken together, HRW treatment promoted growth of seedlings, by stimulating elongation of hypocotyl and root cells, via HRW-induced increase in GA and IAA content in the hypocotyl and the root respectively.
PMID: 32522330
Braz J Microbiol , IF:2.428 , 2020 Jun doi: 10.1007/s42770-020-00301-5
Streptomyces sp. CLV45 from Fabaceae rhizosphere benefits growth of soybean plants.
Escola de Ciencias da Saude e da Vida, Laboratorio de Biotecnologia Vegetal, Pontificia Universidade Catolica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, Rio Grande do Sul, 90619-900, Brazil.; Escola de Ciencias da Saude e da Vida, Laboratorio de Imunologia e Microbiologia, Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre, RS, Brazil.; Escola de Ciencias da Saude e da Vida, Laboratorio de Biotecnologia Vegetal, Pontificia Universidade Catolica do Rio Grande do Sul, Av. Ipiranga 6681, Porto Alegre, Rio Grande do Sul, 90619-900, Brazil. esantarem@pucrs.br.
Plant growth-promoting bacteria such as Streptomyces are an attractive alternative for increasing the sustainability of agricultural systems. In this study, Streptomyces isolates obtained from rhizosphere soil of plants in the family Fabaceae were characterized for their plant growth-promoting traits, including the production of siderophores, 1-aminocyclopropane-1-carboxylate (ACC) deaminase, indole-3-acetic acid (IAA), and phenazines. Soybean seeds were bacterized with selected isolates to test growth promotion. All isolates produced IAA, and the isolate CLV45 was the most efficient, reaching 398.53 mg of IAA per gram of cells. CLV41, CLV45, and CLV46 showed high activity for ACC deaminase whereas CLV42, CLV44, and CLV46 were efficient in siderophore production. Pyocyanin was detected in all isolates; CLV41, CLV43, and CLV45 produced phenazine-carboxylic acid as well. Selected for IAA and ACC deaminase production combined with production of siderophores and phenazines, CLV42, CLV44, and CLV45 were tested for their growth promotion potential. Seed bacterization with CLV45 resulted in plants with increased shoot growth (36.63%) and dry mass (17.97%) compared to control plants. Results suggest that moderate or high levels of auxin and ACC deaminase production by the isolate CLV45 positively affected the growth of soybean plants, making it a strong candidate for further studies on biofertilizer formulation.
PMID: 32529561
Plant Biol (Stuttg) , IF:2.167 , 2020 Jun doi: 10.1111/plb.13154
Exogenous 6-benzyladenine application affects the root morphology, by altering hormonal status, and gene expression of developing lateral root in Malus hupehensis.
College of Horticulture, Northwest Agriculture & Forestry University, Yangling, 712100, China.; College of Life Science, Northwest Agriculture & Forestry University, Yangling, 712100, China.; Department of Agricultural Sciences, the University of Haripur, Haripur, Pakistan.; Beijing Ori-Gene Science and Technology Corp., Ltd, Beijing, 100000, China.
Malus hupehensis is extensively used apple rootstock in China(Mao et al., 2017). In the current study, Malus hupehensis seedlings were treated with exogenous 2.2microM 6-benzyladenine (6-BA) so as to investigate the mechanism by which 6-BAaffects lateral root (LR) development. Results indicated that 6-BA treatment promoted the elongation and thickening of both root and shoot in Malus hupehensis, while reduced the number of LRs, as well as auxin level declined by 6-BA treatment. Moreover, MhAHK4, MhRR1 and MhRR2 were also significantly upregulated in response to 6-BA treatment. Expression levels of auxin synthesis and transport-related genes, such as MhYUCCA6, MhYUCCA10, MhPIN1, and MhPIN2 were downregulated, which corresponded with the lower auxin levels in the 6-BA-treated seedlings. A negative regulator of auxin, MhIAA3 was induced by 6-BA, which leads to declined expression of MhARF7 and MhARF19 in 6-BA-treated seedlings. Resulting, blocked expression of MhWOX11, MhWOX5, MhLBD16 and MhLBD29 were observed, which in turn inhibited LR initiation. In addition, lower auxin level decreased the expression of MhRR7 andMhRR15, which repressed the expression of key transcription factors associated with root development, thus inhibiting LR development. In contrast, 6-BA treatment promoted secondary growth (thickening) of the root by inducing the expression of MhCYCD3;1 and MhCYCD3;2. Collectively, the changes in hormone levels and gene expression resulted in a decreased number of LRs and thicker roots in 6-BA-treated plants.
PMID: 32597557
Physiol Mol Biol Plants , IF:2.005 , 2020 Jun , V26 (6) : P1187-1199 doi: 10.1007/s12298-020-00820-3
Expression of the tomato WRKY gene, SlWRKY23, alters root sensitivity to ethylene, auxin and JA and affects aerial architecture in transgenic Arabidopsis.
Plant Gene Expression Lab, CSIR-National Botanical Research Institute, Lucknow, 226001 India.grid.417642.20000 0000 9068 0476; Integral University, Kursi Road, Lucknow, 226026 India.grid.411723.20000 0004 1756 4240; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002 India.grid.469887.c
WRKY transcription factors (TFs) are a large plant-specific family of TFs that govern development and biotic/abiotic stress responses in plants. We have identified SlWRKY23 as a gene primarily expressed in roots. SlWRKY23 encodes a protein of 320 amino acids that functions as a transcriptional activator. It is transcriptionally up-regulated by ethylene, BAP and salicylic acid treatment but suppressed by IAA. Expression of SlWRKY23 in transgenic Arabidopsis affects sensitivity of roots to ethylene, JA and auxin with transgenic plants showing hypersensitivity to ethylene, JA and auxin-mediated primary root growth inhibition. This hypersensitivity is correlated with higher expression of ERF1 and ARF5 that mediate responses to these hormones. SlWRKY23 expression also affects aerial growth with transgenic plants showing greater number of leaves but smaller rosettes. Flowering time is reduced in transgenic lines and these plants also show a greater number of inflorescence branches, siliques and seeds. The siliques are longer and compactly packed with seeds but seeds are smaller in size. Root biomass shows a 25% decrease in transgenic SlWRKY23 Arabidopsis plants at harvest compared with controls. The studies show that SlWRKY23 regulates plant growth possibly through modulation of genes controlling hormone responses.
PMID: 32549682
J Econ Entomol , IF:1.938 , 2020 Jun , V113 (3) : P1504-1512 doi: 10.1093/jee/toaa058
Analyzing Molecular Basis of Heat-Induced Loss-of-Wheat Resistance to Hessian Fly (Diptera: Cecidomyiidae) Infestation Using RNA-Sequencing.
Department of Biological and Forensic Sciences, Fayetteville State University, Fayetteville, NC.; USDA-ARS and Department of Entomology, Kansas State University, Manhattan, KS.
Heat stress compromises wheat resistance to Hessian fly (HF, Mayetiola destructor (Say)) (Diptera: Cecidomyiidae) infestation. The objective of this research is to analyze the molecular basis of heat-induced loss of wheat resistance to HF infestation using RNA Sequencing (RNA-seq). To this end, two resistant wheat cultivars 'Molly' and 'Caldwell' containing the resistance genes H13 and H6, respectively, were infested with an avirulent HF biotype GP and treated with different temperatures to examine the impact of heat stress on their resistance phenotypes. Tissue samples collected from HF feeding sites in Molly plants were subjected to RNA-seq analysis to determine the effect of heat stress on transcript expression of genes in wheat plants. Our results indicate that resistance to HF infestation in Caldwell is more sensitive to heat stress than that in Molly, and that heat stress down-regulates most genes involved in primary metabolism and biosynthesis of lignin and cuticular wax, but up-regulate most or all genes involved in auxin and 12-oxo-phytodienoic acid (OPDA) signaling pathways. Our results and previous reports suggest that heat stress may impair the processes in wheat plants that produce and mobilize chemical resources needed for synthesizing defensive compounds, weaken cell wall and cuticle defense, decrease OPDA signaling, but increase auxin signaling, leading to the suppressed resistance and activation of susceptibility.
PMID: 32333676
Plant Direct , IF:1.725 , 2020 Jun , V4 (6) : Pe00234 doi: 10.1002/pld3.234
Drought-induced protein (Di19-3) plays a role in auxin signaling by interacting with IAA14 in Arabidopsis.
Interdisciplinary Centre for Plant Genomics & Department of Plant Molecular Biology University of Delhi South Campus New Delhi India.
The members of early auxin response gene family, Aux/IAA, encode negative regulators of auxin signaling but play a central role in auxin-mediated plant development. Here we report the interaction of an Aux/IAA protein, AtIAA14, with Drought-induced-19 (Di19-3) protein and its possible role in auxin signaling. The Atdi19-3 mutant seedlings develop short hypocotyl, both in light and dark, and are compromised in temperature-induced hypocotyl elongation. The mutant plants accumulate more IAA and also show altered expression of NIT2, ILL5, and YUCCA genes involved in auxin biosynthesis and homeostasis, along with many auxin responsive genes like AUX1 and MYB77. Atdi19-3 seedlings show enhanced root growth inhibition when grown in the medium supplemented with auxin. Nevertheless, number of lateral roots is low in Atdi19-3 seedlings grown on the basal medium. We have shown that AtIAA14 physically interacts with AtDi19-3 in yeast two-hybrid (Y2H), bimolecular fluorescence complementation, and in vitro pull-down assays. However, the auxin-induced degradation of AtIAA14 in the Atdi19-3 seedlings was delayed. By expressing pIAA14::mIAA14-GFP in Atdi19-3 mutant background, it became apparent that both Di19-3 and AtIAA14 work in the same pathway and influence lateral root development in Arabidopsis. Gain-of-function slr-1/iaa14 (slr) mutant, like Atdi19-3, showed tolerance to abiotic stress in seed germination and cotyledon greening assays. The Atdi19-3 seedlings showed enhanced sensitivity to ethylene in triple response assay and AgNO3, an ethylene inhibitor, caused profuse lateral root formation in the mutant seedlings. These observations suggest that AtDi19-3 interacting with AtIAA14, in all probability, serves as a positive regulator of auxin signaling and also plays a role in some ethylene-mediated responses in Arabidopsis. Significance Statement: This study has demonstrated interaction of auxin responsive Aux/IAA with Drought-induced 19 (Di19) protein and its possible implication in abiotic stress response.
PMID: 32582877
Plant Signal Behav , IF:1.671 , 2020 Jun : P1782647 doi: 10.1080/15592324.2020.1782647
Bioinformatics analysis of BBX family genes and its response to UV-B in Arabidopsis thaliana.
Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Science, South China Normal University , Guangzhou, China.
The B-box proteins (BBXs) are a family of zinc finger proteins containing one/two B-box domain(s), which play important roles in plant growth and development. Though the Arabidopsis thaliana BBX family genes have been identified and named, no systematic study has taken on BBX family genes involved in the regulation of UV-B induced photomorphogenesis in Arabidopsis thaliana. In our previous report, BBX24/STO was demonstrated to be a negative regulator in UV-B signaling pathway in Arabidopsis. In the present study, the total 32 BBX family genes from Arabidopsis were analyzed, including their structures, conserved domains, phylogenetic relationships, promoter cis-regulatory elements, expression patterns under UV-B radiation. The expression profile of GEO Datasets (GSE117199) related to UV-B in NCBI database was analyzed. qRT-PCR was used to validate the expression profile of several BBX genes in Arabidopsis treated with UV-B. The promoters of AtBBXs contained cis-acting elements that respond to light and hormones, including ethylene, auxin (IAA), abscisic acid (ABA), gibberellin (GA) and methyl jasmonate (MeJA). BBX24 and BBX25 were collinear blocks, suggesting that BBX25 may also be involved in UV-B signal transduction. Expression profile analysis and qRT-PCR validation showed that UV-B induced up-regulation of BBX1, BBX7, BBX20, BBX25 and BBX32, suggesting that AtBBXs were mainly involved in UV-B photomorphogenesis. It is predicted that BBX1, BBX7, BBX20 and BBX25 may be new members in response to UV-B signaling.
PMID: 32552524
Plant Signal Behav , IF:1.671 , 2020 Jun : P1777377 doi: 10.1080/15592324.2020.1777377
Glycosyltransferase UGT76F1 is involved in the temperature-mediated petiole elongation and the BR-mediated hypocotyl growth in Arabidopsis.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education; School of Life Sciences, Shandong University , Qingdao, PR. China.
The signaling network formed by external environmental signals and endogenous hormone signals is an important basis for the adaptive growth of plants. We recently identified a UDP-glucosyltransferase gene, UGT76F1, which controls the glucosylation of auxin precursor IPyA and mediates light-temperature signaling to regulate auxin-dependent hypocotyl elongation in Arabidopsis. However, it is unclear whether UGT76F1 is involved in the adaptive growth of other tissues and whether it is related to the signaling of other hormones besides auxin. Here we investigated the petiole elongation of UGT76F1 overexpression lines and knockout mutant lines, and also studied the effects of UGT76F1 on BR signaling. Experimental results indicated that UGT76F1 is involved in the PIF4-mediated petiole growth under high temperature and that UGT76F1 is also related to the BR signaling in controlling hypocotyl growth. These results suggest that UGT76F1 may have a wider significance in the plant adaptations to surrounding environments.
PMID: 32491966
Plant Signal Behav , IF:1.671 , 2020 Jun , V15 (6) : P1762327 doi: 10.1080/15592324.2020.1762327
Auxin action in developing maize coleoptiles: challenges and open questions.
I-Cultiver, Inc ., San Francisco, CA, USA.; Department of Plant Biology, Carnegie Institution for Science , Stanford, CA, USA.
The year 2020 marks the 150th anniversary of the elucidation of the process of plant organ growth at the cellular level by Julius Sachs (1870). In this Addendum to a Review Article in Molecular Plant, we describe this fundamental discovery and argue that the etiolated grass coleoptile still represents the system of choice for the experimental analysis of auxin (indole-3-acetic acid, IAA)-action. With reference to the phenomenon of 'tissue tension', we discuss the acid-growth hypotheses of IAA-induced wall loosening and the process of vacuolar expansion, respectively. IAA-mediated elongation appears to be independent of wall acidification, and may be regulated via the secretion of glycoproteins into the outer epidermal wall, whereby turgor (and tissue) pressure provides the 'driving force' for growth. As predicted by the "acid growth-hypothesis", the fungal phytotoxin Fusicoccin (Fc) induces organ elongation via the rapid secretion of protons. We conclude that "cell elongation" can only be understood at the level of the entire organ that displays biomechanical features not established by single cells. This systems-level approach can be traced back to the work of Sachs (1870).
PMID: 32403974
Plant Signal Behav , IF:1.671 , 2020 Jun , V15 (6) : P1755504 doi: 10.1080/15592324.2020.1755504
Lateral root development differs between main and secondary roots and depends on the ecotype.
Instituto de Agrobiotecnologia del Litoral, Universidad Nacional del Litoral, CONICET, Centro Cientifico Tecnologico CONICET Santa Fe , Santa Fe, Argentina.
Root architecture depends on the development of the main root and also on the number and density of lateral roots. Most molecular knowledge about the development of lateral roots was acquired studying primary roots, and it was implied that high order roots follow the same pattern. Recently, we informed that AtHB23 is differentially regulated in primary and secondary roots. Here we show that LBD16, a target of AtHB23, also is differentially regulated; it is expressed in the tip of secondary and tertiary roots but not in primary ones. Moreover, the key hormone auxin exhibits a different distribution pattern in secondary and tertiary roots, according to the reporter DR5. Finally, we show that in Col 0 and Ler ecotypes development of secondary and tertiary roots exhibits significant variations. Altogether, we can conclude that different genetic programs govern secondary and tertiary roots development and such processes are dependent on the Arabidopsis genotype.
PMID: 32310024
Mol Biol Rep , IF:1.402 , 2020 Jun , V47 (6) : P4331-4344 doi: 10.1007/s11033-020-05525-0
Genome-wide identification of the ARF (auxin response factor) gene family in peach and their expression analysis.
College of Bioscience and Resources Environment, Beijing University of Agriculture, Beijing, 102206, China.; College of Plant Science and Technology, Beijing University of Agriculture, Beijing, 102206, China.; Pinggu District of Fruit Bureau, Beijing, 101200, China.; College of Bioscience and Resources Environment, Beijing University of Agriculture, Beijing, 102206, China. liuyueping@bua.edu.cn.; Key Laboratory for Northern Urban Agriculture Ministry of Agriculture and Rural Affairs, Beijing University of Agriculture, Beijing, 102206, China. liuyueping@bua.edu.cn.; Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing University of Agriculture, Beijing, 102206, China. liuyueping@bua.edu.cn.
Auxin response factors (ARFs) are important transcription factors to relay auxin signaling. From the Genome Database for Rosaceae (GDR), we identified 17 peach ARF genes (PpARFs) encoding the proteins with three conserved domains. Their gene structure and functional domains were analyzed. Their transcriptional response to exogenous auxin treatment was tested and confirmed. We also expressed PpARF-GFP fusion reporters in tobacco leaves and observed their nuclear localization by fluorescence microscopy. It has been known that ARFs are widely involved in fruit development. We compared the expression pattern of all PpARFs in different tissues including the fruits at different developmental stages of two peach cultivars, "melting" and "stony hard". We found eight PpARFs were more highly expressed in the "melting" peaches compared to "stony hard" peaches, while three PpARFs were more highly expressed in "stony hard" peaches. Among them, the expression difference of PpARF4, PpARF7 and PpARF12 was large, and their function in regulating fruit development and fruit quality was discussed. Our work provides a basis for further exploring the mechanisms underlying auxin regulated peach fruit ripening.
PMID: 32430848
Biotechnol Rep (Amst) , 2020 Jun , V26 : Pe00461 doi: 10.1016/j.btre.2020.e00461
Coinoculation of soybean plants with Bradyrhizobium japonicum and Trichoderma harzianum: Coexistence of both microbes and relief of nitrate inhibition of nodulation.
Laboratorio de Interacciones entre Rizobios y Soja (Lirys), IBBM CCT-La Plata CONICET and Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calles 47 y 115 (1900), La Plata, Argentina.; CIDEFI, CIC-PBA and Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Calles 60 y 119 (1900), La Plata, Argentina.; Rizobacter Argentina SA, Avda. Dr. Arturo Frondizi 1150, Parque Industrial (2700), Pergamino, Argentina.; Laboratorio de Genetica, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, Calles 60 y 119 (1900), La Plata, Argentina.
Coinoculation of plants with mixtures of beneficial microbes sometimes produces synergistic effects. In this study, the effect of soybean coinoculation with the N2-fixing Bradyrhizobium japonicum E109 and the biocontrol fungus Trichoderma harzianum Th5cc was analyzed. Nodulation by E109 was not hampered by Th5cc, which antagonized five out of seven soybean pathogens tested. Furthermore, Th5cc relieved nitrate-inhibition of nodulation, enabling the formation of nodules containing infected cells with bacteroids in the presence of the otherwise inhibitory 10mM KNO3. Th5cc released micromolar amounts of auxin, and addition of 11 muM indoleacetic acid to soybean plants inoculated with E109 in the absence of Th5cc also induced nodulation in the presence of 10mM KNO3. Thus, Th5cc may release auxins into the soybean rhizosphere, which hormones might participate in overcoming the nitrate-inhibition of nodulation. Our results suggest that soybean plants coinoculated with these microorganisms might benefit from biocontrol while contributing to soil-nitrogen preservation.
PMID: 32420051