Nature , IF:42.778 , 2019 Apr , V568 (7751) : P240-243 doi: 10.1038/s41586-019-1069-7
TMK1-mediated auxin signalling regulates differential growth of the apical hook.
Shanghai Center for Plant Stress Biology, Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China.; FAFU-UCR Joint Center, Horticulture Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, China.; University of Chinese Academy of Sciences, Beijing, China.; Institute of Science and Technology Austria, Klosterneuburg, Austria.; FAFU-UCR Joint Center, Horticulture Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, China. tdxu@sibs.ac.cn.
The plant hormone auxin has crucial roles in almost all aspects of plant growth and development. Concentrations of auxin vary across different tissues, mediating distinct developmental outcomes and contributing to the functional diversity of auxin. However, the mechanisms that underlie these activities are poorly understood. Here we identify an auxin signalling mechanism, which acts in parallel to the canonical auxin pathway based on the transport inhibitor response1 (TIR1) and other auxin receptor F-box (AFB) family proteins (TIR1/AFB receptors)(1,2), that translates levels of cellular auxin to mediate differential growth during apical-hook development. This signalling mechanism operates at the concave side of the apical hook, and involves auxin-mediated C-terminal cleavage of transmembrane kinase 1 (TMK1). The cytosolic and nucleus-translocated C terminus of TMK1 specifically interacts with and phosphorylates two non-canonical transcriptional repressors of the auxin or indole-3-acetic acid (Aux/IAA) family (IAA32 and IAA34), thereby regulating ARF transcription factors. In contrast to the degradation of Aux/IAA transcriptional repressors in the canonical pathway, the newly identified mechanism stabilizes the non-canonical IAA32 and IAA34 transcriptional repressors to regulate gene expression and ultimately inhibit growth. The auxin-TMK1 signalling pathway originates at the cell surface, is triggered by high levels of auxin and shares a partially overlapping set of transcription factors with the TIR1/AFB signalling pathway. This allows distinct interpretations of different concentrations of cellular auxin, and thus enables this versatile signalling molecule to mediate complex developmental outcomes.
PMID: 30944466
Science , IF:41.845 , 2019 Apr , V364 (6435) : P57-62 doi: 10.1126/science.aav9959
Developmental control of plant Rho GTPase nano-organization by the lipid phosphatidylserine.
Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342 Lyon, France.; UMR 5200 Membrane Biogenesis Laboratory, CNRS-University of Bordeaux, INRA Bordeaux Aquitaine, 33140 Villenave d'Ornon, France.; Centre de Biochimie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France.; Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, University of Bordeaux, 33000 Bordeaux, France.; BPMP, CNRS, INRA, Montpellier SupAgro, Univ Montpellier, Montpellier, France.; Laboratoire Reproduction et Developpement des Plantes, Universite de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342 Lyon, France. yvon.jaillais@ens-lyon.fr.
Rho guanosine triphosphatases (GTPases) are master regulators of cell signaling, but how they are regulated depending on the cellular context is unclear. We found that the phospholipid phosphatidylserine acts as a developmentally controlled lipid rheostat that tunes Rho GTPase signaling in Arabidopsis Live superresolution single-molecule imaging revealed that the protein Rho of Plants 6 (ROP6) is stabilized by phosphatidylserine into plasma membrane nanodomains, which are required for auxin signaling. Our experiments also revealed that the plasma membrane phosphatidylserine content varies during plant root development and that the level of phosphatidylserine modulates the quantity of ROP6 nanoclusters induced by auxin and hence downstream signaling, including regulation of endocytosis and gravitropism. Our work shows that variations in phosphatidylserine levels are a physiological process that may be leveraged to regulate small GTPase signaling during development.
PMID: 30948546
Annu Rev Plant Biol , IF:19.54 , 2019 Apr , V70 : P293-319 doi: 10.1146/annurev-arplant-050718-100402
The Dynamics of Cambial Stem Cell Activity.
KWS SAAT SE, 37555 Einbeck, Germany.; Umea Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umea, Sweden; email: Rishi.Bhalerao@slu.se.; Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland.; Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, 00014 Helsinki, Finland.; Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom.; Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China.
Stem cell populations in meristematic tissues at distinct locations in the plant body provide the potency of continuous plant growth. Primary meristems, at the apices of the plant body, contribute mainly to the elongation of the main plant axes, whereas secondary meristems in lateral positions are responsible for the thickening of these axes. The stem cells of the vascular cambium-a secondary lateral meristem-produce the secondary phloem (bast) and secondary xylem (wood). The sites of primary and secondary growth are spatially separated, and mobile signals are expected to coordinate growth rates between apical and lateral stem cell populations. Although the underlying mechanisms have not yet been uncovered, it seems likely that hormones, peptides, and mechanical cues orchestrate primary and secondary growth. In this review, we highlight the current knowledge and recent discoveries of how cambial stem cell activity is regulated, with a focus on mobile signals and the response of cambial activity to environmental and stress factors.
PMID: 30822110
Annu Rev Plant Biol , IF:19.54 , 2019 Apr , V70 : P377-406 doi: 10.1146/annurev-arplant-050718-100434
Molecular Mechanisms of Plant Regeneration.
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; email: momoko.ikeuchi@riken.jp , david.favero@riken.jp , yuki.sakamoto.zu@riken.jp , akira.iwase@riken.jp , duncan.coleman@riken.jp , bart.rymen@riken.jp , keiko.sugimoto@riken.jp.; Department of Biological Sciences, University of Tokyo, Tokyo 119-0033, Japan.
Plants reprogram somatic cells following injury and regenerate new tissues and organs. Upon perception of inductive cues, somatic cells often dedifferentiate, proliferate, and acquire new fates to repair damaged tissues or develop new organs from wound sites. Wound stress activates transcriptional cascades to promote cell fate reprogramming and initiate new developmental programs. Wounding also modulates endogenous hormonal responses by triggering their biosynthesis and/or directional transport. Auxin and cytokinin play pivotal roles in determining cell fates in regenerating tissues and organs. Exogenous application of these plant hormones enhances regenerative responses in vitro by facilitating the activation of specific developmental programs. Many reprogramming regulators are epigenetically silenced during normal development but are activated by wound stress and/or hormonal cues.
PMID: 30786238
Annu Rev Plant Biol , IF:19.54 , 2019 Apr , V70 : P321-346 doi: 10.1146/annurev-arplant-050718-095919
Thermomorphogenesis.
Instituto de Investigaciones Fisiologicas y Ecologicas Vinculadas a la Agricultura (IFEVA), Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) and Facultad de Agronomia, Universidad de Buenos Aires, C1417DSE Buenos Aires, Argentina; email: casal@ifeva.edu.ar.; Instituto de Investigaciones Bioquimicas de Buenos Aires, Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) and Fundacion Instituto Leloir, C1405BWE Buenos Aires, Argentina.; School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia; email: mb.suresh@monash.edu.
When exposed to warmer, nonstressful average temperatures, some plant organs grow and develop at a faster rate without affecting their final dimensions. Other plant organs show specific changes in morphology or development in a response termed thermomorphogenesis. Selected coding and noncoding RNA, chromatin features, alternative splicing variants, and signaling proteins change their abundance, localization, and/or intrinsic activity to mediate thermomorphogenesis. Temperature, light, and circadian clock cues are integrated to impinge on the level or signaling of hormones such as auxin, brassinosteroids, and gibberellins. The light receptor phytochrome B (phyB) is a temperature sensor, and the phyB-PHYTOCHROME-INTERACTING FACTOR 4 (PIF4)-auxin module is only one thread in a complex network that governs temperature sensitivity. Thermomorphogenesis offers an avenue to search for climate-smart plants to sustain crop and pasture productivity in the context of global climate change.
PMID: 30786235
Nat Plants , IF:13.256 , 2019 Apr , V5 (4) : P414-423 doi: 10.1038/s41477-019-0396-x
A MAPK cascade downstream of IDA-HAE/HSL2 ligand-receptor pair in lateral root emergence.
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China.; Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Nanjing, Jiangsu, China.; Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, MO, USA.; Division of Biological Sciences, Interdisciplinary Plant Group, University of Missouri, Columbia, MO, USA.; Division of Biochemistry, Interdisciplinary Plant Group, Bond Life Sciences Center, University of Missouri, Columbia, MO, USA. Zhangsh@missouri.edu.; State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, China. xujuan@zju.edu.cn.
Lateral root (LR) emergence is a highly coordinated process involving precise cell-cell communication. Here, we show that MITOGEN-ACTIVATED PROTEIN KINASE3 (MPK3) and MPK6, and their upstream MAP-kinase kinases (MAPKKs), MKK4 and MKK5, function downstream of HAESA (HAE)/HAESA-LIKE2 (HSL2) and their ligand INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) during LR emergence. Loss of function of MKK4/MKK5 or MPK3/MPK6 results in restricted passage of the growing lateral root primordia (LRP) through the overlaying endodermal, cortical and epidermal cell layers, leading to reduced LR density. The MKK4/MKK5-MPK3/MPK6 module regulates the expression of cell wall remodelling genes in cells overlaying LRP and therefore controls pectin degradation in the middle lamella. Expression of constitutively active MKK4 or MKK5 driven by the HAE or HSL2 promoter fully rescues the LR emergence defect in the ida and hae hsl2 mutants. In addition, the MKK4/MKK5-MPK3/MPK6 module is indispensable in auxin-facilitated LR emergence. Our study provides insights into the auxin-governed and IDA-HAE/HLS2 ligand-receptor pair-mediated LR emergence process.
PMID: 30936437
Mol Plant , IF:12.084 , 2019 Apr , V12 (4) : P538-551 doi: 10.1016/j.molp.2019.01.007
Endogenous Hypoxia in Lateral Root Primordia Controls Root Architecture by Antagonizing Auxin Signaling in Arabidopsis.
Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy.; Biology Department, University of Pisa, Pisa, Italy.; Laboratory of Growth Regulators, Centre of the Region Hana for Biotechnological and Agricultural Research, Institute of Experimental Botany CAS & Faculty of Science, Palacky University, Slechtitelu 27, 78371 Olomouc, Czech Republic.; Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy; Biology Department, University of Pisa, Pisa, Italy. Electronic address: beatrice.giuntoli@unipi.it.; Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy; Biology Department, University of Pisa, Pisa, Italy. Electronic address: francesco.licausi@unipi.it.
As non-photosynthesizing organs, roots are dependent on diffusion of oxygen from the external environment and, in some instances, from the shoot for their aerobic metabolism. Establishment of hypoxic niches in the developing tissues of plants has been postulated as a consequence of insufficient diffusion of oxygen to satisfy the demands throughout development. Here, we report that such niches are established at specific stages of lateral root primordia development in Arabidopsis thaliana grown under aerobic conditions. Using gain- and loss-of-function mutants, we show that ERF-VII transcription factors, which mediate hypoxic responses, control root architecture by acting in cells with a high level of auxin signaling. ERF-VIIs repress the expression of the auxin-induced genes LBD16, LBD18, and PUCHI, which are essential for lateral root development, by binding to their promoters. Our results support a model in which the establishment of hypoxic niches in the developing lateral root primordia contributes to the shutting down of key auxin-induced genes and regulates the production of lateral roots.
PMID: 30641154
Mol Plant , IF:12.084 , 2019 Apr , V12 (4) : P521-537 doi: 10.1016/j.molp.2018.12.021
A Crucial Role of GA-Regulated Flavonol Biosynthesis in Root Growth of Arabidopsis.
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China.; National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.; Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai 200234, China. Electronic address: huangjr@shnu.edu.cn.
Flavonols have been demonstrated to play many important roles in plant growth, development, and communication with other organisms. Flavonol biosynthesis is spatiotemporally regulated by the subgroup 7 R2R3-MYB (SG7 MYB) transcription factors including MYB11/MYB12/MYB111. However, whether SG7-MYB activity is subject to post-translational regulation remains unclear. Here, we show that gibberellic acid (GA) inhibits flavonol biosynthesis via DELLA proteins in Arabidopsis. Protein-protein interaction analyses revealed that DELLAs (RGA and GAI) interacted with SG7 MYBs (MYB12 and MYB111) both in vitro and in vivo, leading to enhanced affinity of MYB binding to the promoter regions of key genes for flavonol biosynthesis and thus increasing their transcriptional levels. We observed that the level of auxin in the root tip was negatively correlated with root flavonol content. Furthermore, genetic assays showed that loss-of-function mutations in MYB12, which is predominantly expressed in roots, partially rescued the short-root phenotype of the GA-deficient mutant ga1-3 by increasing root meristem size and mature cell size. Consistent with these observations, exogenous application of the flavonol quercetin restored the root meristem size of myb12 ga1-3 to that of ga1-3. Taken together, our data elucidate a molecular mechanism by which GA promotes root growth by directly reducing flavonol biosynthesis.
PMID: 30630075
Curr Biol , IF:9.601 , 2019 Apr , V29 (7) : P1199-1205.e4 doi: 10.1016/j.cub.2019.02.022
The Lateral Root Cap Acts as an Auxin Sink that Controls Meristem Size.
Department of Biology, University of Pisa - via L. Ghini, 13 - 56126 Pisa, Italy. Electronic address: riccardo.dimambro@unipi.it.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza - via dei Sardi, 70 - 00185 Rome, Italy.; Istituto di Biologia e Biotecnologia Agraria, Consiglio Nazionale delle Ricerche - Via Alfonso Corti, 12 - 20133 Milano, Italy.; Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, United States.; Department of Biology and Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA.; Plant Molecular and Cellular Biology Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza - via dei Sardi, 70 - 00185 Rome, Italy. Electronic address: sabrina.sabatini@uniroma1.it.
Plant developmental plasticity relies on the activities of meristems, regions where stem cells continuously produce new cells [1]. The lateral root cap (LRC) is the outermost tissue of the root meristem [1], and it is known to play an important role during root development [2-6]. In particular, it has been shown that mechanical or genetic ablation of LRC cells affect meristem size [7, 8]; however, the molecular mechanisms involved are unknown. Root meristem size and, consequently, root growth depend on the position of the transition zone (TZ), a boundary that separates dividing from differentiating cells [9, 10]. The interaction of two phytohormones, cytokinin and auxin, is fundamental in controlling the position of the TZ [9, 10]. Cytokinin via the ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1) control auxin distribution within the meristem, generating an instructive auxin minimum that positions the TZ [10]. We identify a cytokinin-dependent molecular mechanism that acts in the LRC to control the position of the TZ and meristem size. We show that auxin levels within the LRC cells depends on PIN-FORMED 5 (PIN5), a cytokinin-activated intracellular transporter that pumps auxin from the cytoplasm into the endoplasmic reticulum, and on irreversible auxin conjugation mediated by the IAA-amino synthase GRETCHEN HAGEN 3.17 (GH3.17). By titrating auxin in the LRC, the PIN5 and the GH3.17 genes control auxin levels in the entire root meristem. Overall, our results indicate that the LRC serves as an auxin sink that, under the control of cytokinin, regulates meristem size and root growth.
PMID: 30880016
Genes Dev , IF:9.527 , 2019 Apr , V33 (7-8) : P466-476 doi: 10.1101/gad.316554.118
Auxin regulates endosperm cellularization in Arabidopsis.
Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 7080 Uppsala, Sweden.
The endosperm is an ephemeral tissue that nourishes the developing embryo, similar to the placenta in mammals. In most angiosperms, endosperm development starts as a syncytium, in which nuclear divisions are not followed by cytokinesis. The timing of endosperm cellularization largely varies between species, and the event triggering this transition remains unknown. Here we show that increased auxin biosynthesis in the endosperm prevents its cellularization, leading to seed arrest. Auxin-overproducing seeds phenocopy paternal-excess triploid seeds derived from hybridizations of diploid maternal plants with tetraploid fathers. Concurrently, auxin-related genes are strongly overexpressed in triploid seeds, correlating with increased auxin activity. Reducing auxin biosynthesis and signaling reestablishes endosperm cellularization in triploid seeds and restores their viability, highlighting a causal role of increased auxin in preventing endosperm cellularization. We propose that auxin determines the time of endosperm cellularization, and thereby uncovered a central role of auxin in establishing hybridization barriers in plants.
PMID: 30819818
Proc Natl Acad Sci U S A , IF:9.412 , 2019 Apr , V116 (17) : P8597-8602 doi: 10.1073/pnas.1820882116
EXPANSIN A1-mediated radial swelling of pericycle cells positions anticlinal cell divisions during lateral root initiation.
School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, United Kingdom.; Centre for Plant Integrative Biology, University of Nottingham, Sutton Bonington LE12 5RD, United Kingdom.; Center for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany.; Nanoscale and Microscale Research Centre, University of Nottingham, Nottingham NG7 2RD, United Kingdom.; Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium.; Center for Plant Systems Biology, VIB, B-9052 Ghent, Belgium.; VIB-UGent Center for Medical Biotechnology, B-9000 Ghent, Belgium.; Department of Biomolecular Medicine, Ghent University, B-9000 Ghent, Belgium.; Department of Plant and Environmental Sciences, University of Copenhagen, 1871 Frederiksberg C, Denmark.; Center for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany; alexis.maizel@cos.uni-heidelberg.de ivsme@psb.vib-ugent.be.; School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, United Kingdom; alexis.maizel@cos.uni-heidelberg.de ivsme@psb.vib-ugent.be.
In plants, postembryonic formation of new organs helps shape the adult organism. This requires the tight regulation of when and where a new organ is formed and a coordination of the underlying cell divisions. To build a root system, new lateral roots are continuously developing, and this process requires the tight coordination of asymmetric cell division in adjacent pericycle cells. We identified EXPANSIN A1 (EXPA1) as a cell wall modifying enzyme controlling the divisions marking lateral root initiation. Loss of EXPA1 leads to defects in the first asymmetric pericycle cell divisions and the radial swelling of the pericycle during auxin-driven lateral root formation. We conclude that a localized radial expansion of adjacent pericycle cells is required to position the asymmetric cell divisions and generate a core of small daughter cells, which is a prerequisite for lateral root organogenesis.
PMID: 30944225
New Phytol , IF:8.512 , 2019 Apr , V222 (2) : P752-767 doi: 10.1111/nph.15658
Auxin-mediated Aux/IAA-ARF-HB signaling cascade regulates secondary xylem development in Populus.
Chongqing Key Laboratory of Plant Resource Conservation and Germplasm Innovation, School of Life Sciences, Southwest University, Chongqing, 400715, China.; School of Basic Medical Sciences, Southwest Medical University, Luzhou, Sichuan, 646000, China.; Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, 810008, China.; UMR5546, Laboratoire de Recherche en Sciences Vegetales, Universite de Toulouse III Paul Sabatier, CNRS, UPS, 31326, Castanet-Tolosan, France.
Wood development is strictly regulated by various phytohormones and auxin plays a central regulatory role in this process. However, how the auxin signaling is transducted in developing secondary xylem during wood formation in tree species remains unclear. Here, we identified an Aux/INDOLE-3-ACETIC ACID 9 (IAA9)-AUXIN RESPONSE FACTOR 5 (ARF5) module in Populus tomentosa as a key mediator of auxin signaling to control early developing xylem development. PtoIAA9, a canonical Aux/IAA gene, is predominantly expressed in vascular cambium and developing secondary xylem and induced by exogenous auxin. Overexpression of PtoIAA9m encoding a stabilized IAA9 protein significantly represses secondary xylem development in transgenic poplar. We further showed that PtoIAA9 interacts with PtoARF5 homologs via the C-terminal III/IV domains. The truncated PtoARF5.1 protein without the III/IV domains rescued defective phenotypes caused by PtoIAA9m. Expression analysis showed that the PtoIAA9-PtoARF5 module regulated the expression of genes associated with secondary vascular development in PtoIAA9m- and PtoARF5.1-overexpressing plants. Furthermore, PtoARF5.1 could bind to the promoters of two Class III homeodomain-leucine zipper (HD-ZIP III) genes, PtoHB7 and PtoHB8, to modulate secondary xylem formation. Taken together, our results suggest that the Aux/IAA9-ARF5 module is required for auxin signaling to regulate wood formation via orchestrating the expression of HD-ZIP III transcription factors in poplar.
PMID: 30582614
New Phytol , IF:8.512 , 2019 Apr , V222 (2) : P837-851 doi: 10.1111/nph.15632
An auxin signaling gene BnaA3.IAA7 contributes to improved plant architecture and yield heterosis in rapeseed.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China.; Southern Cross Plant Science, Southern Cross University, Lismore, NSW, 2480, Australia.
Plant architecture is the key factor affecting overall yield in many crops. The genetic basis underlying plant architecture in rapeseed (Brassica napus), a key global oil crop, is elusive. We characterized an ethyl methanesulfonate (EMS)-mutagenized rapeseed mutant, sca, which had multiple phenotypic alterations, including crinkled leaves, semi-dwarf stature, narrow branch angles and upward-standing siliques. We identified the underlying gene, which encodes an Aux/IAA protein (BnaA3.IAA7). A G-to-A mutation changed the glycine at the 84(th) position to glutamic acid (G84E), disrupting the conserved degron motif GWPPV and reducing the affinity between BnaA3.IAA7 and TIR1 (TRANSPORT INHIBITOR RESPONSE 1) in an auxin dosage-dependent manner. This change repressed the degradation of BnaA3.IAA7 and therefore repressed auxin signaling at low levels of auxin that reduced the length of internodes. The G84E mutation reduced branch angles by enhancing the gravitropic response. The heterozygote +/sca closely resembled a proposed ideal plant architecture, displaying strong yield heterosis through single-locus overdominance by improving multiple component traits. Our findings demonstrate that a weak gain-of-function mutation in BnaA3.IAA7 contributes to yield heterosis by improving plant architecture and would be valuable for breeding superior rapeseed hybrid cultivars and such a mutation may increase the yield in other Brassica crops.
PMID: 30536633
New Phytol , IF:8.512 , 2019 Apr , V222 (2) : P820-836 doi: 10.1111/nph.15618
The RIN-regulated Small Auxin-Up RNA SAUR69 is involved in the unripe-to-ripe phase transition of tomato fruit via enhancement of the sensitivity to ethylene.
GBF Laboratory, Universite de Toulouse, INRA, Castanet-Tolosan, 31320, France.; Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, Sichuan, China.; Laboratory of Plant Physiology, Institute of Biosciences, Department of Botany, Universidade de Sao Paulo, Sao Paulo, 11461, Brazil.; Laboratoire de Reproduction et Developpement des Plantes, CNRS, INRA, ENS de Lyon, UCBL, Universite de Lyon, Lyon, 69364, France.
Ethylene is the main hormone controlling climacteric fruit ripening; however, the mechanisms underlying the developmental transition leading to the initiation of the ripening process remain elusive, although the presumed role of active hormone interplay has often been postulated. To unravel the putative role of auxin in the unripe-to-ripe transition, we investigated the dynamics of auxin activity in tomato fruit and addressed the physiological significance of Sl-SAUR69, previously identified as a RIN target gene, using reverse genetics approaches. Auxin signalling undergoes dramatic decline at the onset of ripening in wild-type fruit, but not in the nonripening rin mutant. Sl-SAUR69 exhibits reduced expression in rin and its up-regulation results in premature initiation of ripening, whereas its down-regulation extends the time to ripening. Overexpression of Sl-SAUR69 reduces proton pump activity and polar auxin transport, and ectopic expression in Arabidopsis alters auxin transporter abundance, further arguing for its active role in the regulation of auxin transport. The data support a model in which Sl-SAUR69 represses auxin transport, thus generating auxin minima, which results in enhanced ethylene sensitivity. This defines a regulation loop, fed by ethylene and auxin as the main hormonal signals and by RIN and Sl-SAUR69 as modulators of the balance between the two hormones.
PMID: 30511456
Curr Opin Biotechnol , IF:8.288 , 2019 Apr , V56 : P156-162 doi: 10.1016/j.copbio.2018.11.012
Bioactivity: phenylpropanoids' best kept secret.
Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 927, B-9052 Gent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 927, B-9052 Gent, Belgium. Electronic address: bartel.vanholme@ugent.vib.be.; Ghent University, Department of Plant Biotechnology and Bioinformatics, Technologiepark 927, B-9052 Gent, Belgium; VIB Center for Plant Systems Biology, Technologiepark 927, B-9052 Gent, Belgium.
Plant growth and development are tightly regulated by compounds produced in trace amounts in the plant. Besides the classical phytohormones, many plant metabolites have been described to affect plant development. Among these are several phenylpropanoids, although conclusive evidence for their bioactivity at physiologically relevant concentrations is only available for cinnamic acid. By inhibition of auxin efflux transport, the cis-isoform of cinnamic acid alters auxin homeostasis, resulting in auxin-related growth effects. Despite insight into its mode of action, the molecular target of cis-cinnamic acid is not yet known, and it remains to be determined whether this or other phenylpropanoids have a role to play in regulating plant growth and development under normal or stress conditions.
PMID: 30530240
Plant Biotechnol J , IF:8.154 , 2019 Apr , V17 (4) : P712-723 doi: 10.1111/pbi.13009
miR1432-OsACOT (Acyl-CoA thioesterase) module determines grain yield via enhancing grain filling rate in rice.
Collaborative Innovation Center of Henan Grain Crops, Henan Agricultural University, Zhengzhou, China.; Key Laboratory of Rice Biology in Henan Province, Henan Agricultural University, Zhengzhou, China.; Department of Biological Sciences and Biotechnology Research Center (BRC), Michigan Technological University, Houghton, MI, USA.; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences (CAS), Shanghai, China.
Rice grain filling rate contributes largely to grain productivity and accumulation of nutrients. MicroRNAs (miRNAs) are key regulators of development and physiology in plants and become a novel key target for engineering grain size and crop yield. However, there is little studies, so far, showing the miRNA regulation of grain filling and rice yield, in consequence. Here, we show that suppressed expression of rice miR1432 (STTM1432) significantly improves grain weight by enhancing grain filling rate and leads to an increase in overall grain yield up to 17.14% in a field trial. Molecular analysis identified rice Acyl-CoA thioesterase (OsACOT), which is conserved with ACOT13 in other species, as a major target of miR1432 by cleavage. Moreover, overexpression of miR1432-resistant form of OsACOT (OXmACOT) resembled the STTM1432 plants, that is, a large margin of an increase in grain weight up to 46.69% through improving the grain filling rate. Further study indicated that OsACOT was involved in biosynthesis of medium-chain fatty acids. In addition, RNA-seq based transcriptomic analyses of transgenic plants with altered expression of miR1432 demonstrated that downstream genes of miR1432-regulated network are involved in fatty acid metabolism and phytohormones biosynthesis and also overlap with the enrichment analysis of co-expressed genes of OsACOT, which is consistent with the increased levels of auxin and abscisic acid in STTM1432 and OXmACOT plants. Overall, miR1432-OsACOT module plays an important role in grain filling in rice, illustrating its capacity for engineering yield improvement in crops.
PMID: 30183128
Plant Cell Environ , IF:6.362 , 2019 Apr , V42 (4) : P1125-1138 doi: 10.1111/pce.13478
The auxin influx carrier, OsAUX3, regulates rice root development and responses to aluminium stress.
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.; Vegetable Research Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.; State Key Laboratory of Plant Genomics, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.; Department of Biology, University of Fribourg, Fribourg, CH-1700, Switzerland.; State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, 310006, China.
In rice, there are five members of the auxin carrier AUXIN1/LIKE AUX1 family; however, the biological functions of the other four members besides OsAUX1 remain unknown. Here, by using CRISPR/Cas9, we constructed two independent OsAUX3 knock-down lines, osaux3-1 and osaux3-2, in wild-type rice, Hwayoung (WT/HY) and Dongjin (WT/DJ). osaux3-1 and osaux3-2 have shorter primary roots (PRs), decreased lateral root (LR) density, and longer root hairs (RHs) compared with their WT. OsAUX3 expression in PRs, LRs, and RHs further supports that OsAUX3 plays a critical role in the regulation of root development. OsAUX3 locates at the plasma membrane and functions as an auxin influx carrier affecting acropetal auxin transport. OsAUX3 is up-regulated in the root apex under aluminium (Al) stress, and osaux3-2 is insensitive to Al treatments. Furthermore, 1-naphthylacetic acid accented the sensitivity of WT/DJ and osaux3-2 to respond to Al stress. Auxin concentrations, Al contents, and Al-induced reactive oxygen species-mediated damage in osaux3-2 under Al stress are lower than in WT, indicating that OsAUX3 is involved in Al-induced inhibition of root growth. This study uncovers a novel pathway alleviating Al-induced oxidative damage by inhibition of acropetal auxin transport and provides a new option for engineering Al-tolerant rice species.
PMID: 30399648
Plant Cell Environ , IF:6.362 , 2019 Apr , V42 (4) : P1205-1221 doi: 10.1111/pce.13444
Tomato stigma exsertion induced by high temperature is associated with the jasmonate signalling pathway.
Department of Horticulture, Zhejiang University, Hangzhou, China.; Boyce Thompson Institute, Cornell University, Ithaca, New York, USA.; College of Horticulture, Northeast Agricultural University, Harbin, China.; USDA Robert W. Holley Center for Agriculture and Health, Ithaca, New York, USA.; Key Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Ministry of Agricultural, Zhejiang University, Hangzhou, China.
High temperature (HT) is becoming an increasingly serious factor in limiting crop production with global climate change. During hot seasons, owing to prevailing HT, cultivated tomatoes are prone to exhibiting stigma exsertion, which hampers pollination and causes fruit set failure. However, the underlying regulatory mechanisms of the HT-induced stigma exsertion remain largely unknown. Here, we demonstrate that stigma exsertion induced by HT in cultivated tomato is caused by more seriously shortened stamens than pistils, which is different from the stigma exsertion observed in wild tomato species. Under the HT condition, the different responses of pectin, sugar, expansin, and cyclin cause cell wall remodelling and differentially localized cell division and selective cell enlargement, which further determine the lengths of stamens and pistils. In addition, auxin and jasmonate (JA) are implicated in regulating cell division and cell expansion in stamens and pistils, and exogenous JA instead of auxin treatment can effectively rescue tomato stigma exsertion through regulating the JA/COI1 signalling pathway. Our findings provide a better understanding of stigma exsertions under the HT condition in tomato and uncover a new function of JA in improving plant abiotic stress tolerance.
PMID: 30203844
Plant J , IF:6.141 , 2019 Apr , V98 (2) : P346-358 doi: 10.1111/tpj.14223
Enhancing microRNA167A expression in seed decreases the alpha-linolenic acid content and increases seed size in Camelina sativa.
Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT, 59717, USA.; HudsonAlpha Institute of Biotechnology, Huntsville, AL, 35806, USA.; US Department of Energy Joint Genome Institute, Walnut Creek, CA, 94598, USA.
Despite well established roles of microRNAs in plant development, few aspects have been addressed to understand their effects in seeds especially on lipid metabolism. In this study, we showed that overexpressing microRNA167A (miR167OE) in camelina (Camelina sativa) under a seed-specific promoter changed fatty acid composition and increased seed size. Specifically, the miR167OE seeds had a lower alpha-linolenic acid with a concomitantly higher linoleic acid content than the wild-type. This decreased level of fatty acid desaturation corresponded to a decreased transcriptional expression of the camelina fatty acid desaturase3 (CsFAD3) in developing seeds. MiR167 targeted the transcription factor auxin response factor (CsARF8) in camelina, as had been reported previously in Arabidopsis. Chromatin immunoprecipitation experiments combined with transcriptome analysis indicated that CsARF8 bound to promoters of camelina bZIP67 and ABI3 genes. These transcription factors directly or through the ABI3-bZIP12 pathway regulate CsFAD3 expression and affect alpha-linolenic acid accumulation. In addition, to decipher the miR167A-CsARF8 mediated transcriptional cascade for CsFAD3 suppression, transcriptome analysis was conducted to implicate mechanisms that regulate seed size in camelina. Expression levels of many genes were altered in miR167OE, including orthologs that have previously been identified to affect seed size in other plants. Most notably, genes for seed coat development such as suberin and lignin biosynthesis were down-regulated. This study provides valuable insights into the regulatory mechanism of fatty acid metabolism and seed size determination, and suggests possible approaches to improve these important traits in camelina.
PMID: 30604453
Plant J , IF:6.141 , 2019 Apr , V98 (1) : P97-111 doi: 10.1111/tpj.14202
Gene networks orchestrated by MeGI: a single-factor mechanism underlying sex determination in persimmon.
Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan.; Japan Science and Technology Agency (JST), PRESTO, Kawaguchi-shi, Saitama, 332-0012, Japan.; Division of Biotechnology, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, 305-8602, Japan.
Separating male and female sex organs is one of the main strategies used to maintain genetic diversity within a species. However, the genetic determinants and their regulatory mechanisms have been identified in only a few species. In dioecious persimmons, the homeodomain transcription factor, MeGI, which is the target of a Y chromosome-encoded small-RNA, OGI, can determine floral sexuality. The basic features of this system are conserved in the monoecious hexaploid Oriental persimmon, in which an additional epigenetic regulation of MeGI determines floral sexuality. The downstream regulatory pathways of MeGI remain uncharacterized. In this study, we examined transcriptomic data for male and female flowers from monoecious persimmon cultivars to unveil the gene networks orchestrated by MeGI. A network visualization and cistrome assessment suggested that class-1 KNOTTED-like homeobox (KNOX)/ovate family protein (OFP)/growth regulating factors (GRFs) and short vegetative phase (SVP) genes mediate the differences in gynoecium and androecium development between male and female flowers, respectively. The expression of these genes is directly controlled by MeGI. The gene networks also suggested that some cytokinin, auxin, and gibberellin signaling genes function cooperatively in the KNOX/OFP/GRF pathway during gynoecium differentiation. Meanwhile, SVP may repress PI expression in developing androecia. Overall, our results suggest that MeGI evolved the ability to promote gynoecium development and suppress androecium development by regulating KNOX/OFP/GRF and SVP expression levels, respectively. These insights may help to clarify the molecular mechanism underlying the production of unisexual flowers, while also elucidating the physiological background enabling a single-factor system to establish dioecy in plants.
PMID: 30556936
J Exp Bot , IF:5.908 , 2019 Apr , V70 (8) : P2211-2216 doi: 10.1093/jxb/erz108
Target of Rapamycin kinase: central regulatory hub for plant growth and metabolism.
Institut de Biologie Moleculaire des Plantes, UPR 2357 CNRS, Universite de Strasbourg, Strasbourg, France.; Laboratoire de Genetique et Biophysique des Plantes, UMR 7265, Aix Marseille Universite, CEA, CNRS, BIAM, Faculte des Sciences de Luminy, Marseille, France.; Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Universite Paris-Saclay, Versailles, France.
PMID: 30984977
J Exp Bot , IF:5.908 , 2019 Apr , V70 (7) : P2157-2171 doi: 10.1093/jxb/erz059
An atypical aspartic protease modulates lateral root development in Arabidopsis thaliana.
PhD Programme in Experimental Biology and Biomedicine, Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.; Institute for Interdisciplinary Research, University of Coimbra, Portugal.; CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.; Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA.; Central Institute for Engineering, Electronics and Analytics, ZEA-3, Forschungszentrum Julich, Julich, Germany.; Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna, Austria.
Few atypical aspartic proteases (APs) present in plants have been functionally studied to date despite having been implicated in developmental processes and stress responses. Here we characterize a novel atypical AP that we name Atypical Aspartic Protease in Roots 1 (ASPR1), denoting its expression in Arabidopsis roots. Recombinant ASPR1 produced by transient expression in Nicotiana benthamiana was active and displayed atypical properties, combining optimum acidic pH, partial sensitivity to pepstatin, pronounced sensitivity to redox agents, and unique specificity preferences resembling those of fungal APs. ASPR1 overexpression suppressed primary root growth and lateral root development, implying a previously unknown biological role for an AP. Quantitative comparison of wild-type and aspr1 root proteomes revealed deregulation of proteins associated with both reactive oxygen species and auxin homeostasis in the mutant. Together, our findings on ASPR1 reinforce the diverse pattern of enzymatic properties and biological roles of atypical APs and raise exciting questions on how these distinctive features impact functional specialization among these proteases.
PMID: 30778561
J Ginseng Res , IF:5.487 , 2019 Apr , V43 (2) : P261-271 doi: 10.1016/j.jgr.2018.02.005
Production of ginsenoside aglycone (protopanaxatriol) and male sterility of transgenic tobacco co-overexpressing three Panax ginseng genes: PgDDS, CYP716A47, and CYP716A53v2.
Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chuncheon, Republic of Korea.
Background: Protopanaxatriol (PPT) is an aglycone of ginsenosides, which has high medicinal values. Production of PPT from natural ginseng plants requires artificial deglycosylation procedures of ginsenosides via enzymatic or physicochemical treatments. Metabolic engineering could be an efficient technology for production of ginsenoside sapogenin. For PPT biosynthesis in Panax ginseng, damarenediol-II synthase (PgDDS) and two cytochrome P450 enzymes (CYP716A47 and CYP716A53v2) are essentially required. Methods: Transgenic tobacco co-overexpressing P. ginseng PgDDS, CYP716A47, and CYP716A53v2 was constructed via Agrobacterium-mediated transformation. Results: Expression of the three introduced genes in transgenic tobacco lines was confirmed by Reverse transcription-polymerase chain reaction (RT-PCR). Analysis of liquid chromatography showed three new peaks, dammarenediol-II (DD), protopanaxadiol (PPD), and PPT, in leaves of transgenic tobacco. Transgenic tobacco (line 6) contained 2.8 mug/g dry weight (DW), 7.3 mug/g DW, and 11.6 mug/g DW of PPT, PPD, and DD in leaves, respectively. Production of PPT was achieved via cell suspension culture and was highly affected by auxin treatment. The content of PPT in cell suspension was increased 37.25-fold compared with that of leaves of the transgenic tobacco. Transgenic tobacco was not able to set seeds because of microspore degeneration in anthers. Transmission electron microscopy analysis revealed that cells of phloem tissue situated in the center of the anther showed an abnormally condensed nuclei and degenerated mitochondria. Conclusion: We successfully achieved the production of PPT in transgenic tobacco. The possible factors deriving male sterility in transgenic tobacco are discussed.
PMID: 30976164
PLoS Genet , IF:5.174 , 2019 Apr , V15 (4) : Pe1008094 doi: 10.1371/journal.pgen.1008094
Canonical cytosolic iron-sulfur cluster assembly and non-canonical functions of DRE2 in Arabidopsis.
State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.; Academy for Advanced Interdisciplinary Studies, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China.
As a component of the Cytosolic Iron-sulfur cluster Assembly (CIA) pathway, DRE2 is essential in organisms from yeast to mammals. However, the roles of DRE2 remain incompletely understood largely due to the lack of viable dre2 mutants. In this study, we successfully created hypomorphic dre2 mutants using the CRISPR/Cas9 technology. Like other CIA pathway mutants, the dre2 mutants have accumulation of DNA lesions and show constitutive DNA damage response. In addition, the dre2 mutants exhibit DNA hypermethylation at hundreds of loci. The mutant forms of DRE2 in the dre2 mutants, which bear deletions in the linker region of DRE2, lost interaction with GRXS17 but have stronger interaction with NBP35, resulting in the CIA-related defects of dre2. Interestingly, we find that DRE2 is also involved in auxin response that may be independent of its CIA role. DRE2 localizes in both the cytoplasm and the nucleus and nuclear DRE2 associates with euchromatin. Furthermore, DRE2 directly associates with multiple auxin responsive genes and maintains their normal expression. Our study highlights the importance of the linker region of DRE2 in coordinating CIA-related protein interactions and identifies the canonical and non-canonical roles of DRE2 in maintaining genome stability, epigenomic patterns, and auxin response.
PMID: 31034471
Int J Biol Macromol , IF:5.162 , 2019 Apr , V126 : P91-100 doi: 10.1016/j.ijbiomac.2018.12.118
Effects of chitosan nanoparticles on seed germination and seedling growth of wheat (Triticum aestivum L.).
Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; School of Environment Science and Engineering, Dalian Maritime University, Dalian 116026, China.; Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; School of Food Science and Engineering, Dalian Ocean University, Dalian 116023, China.; Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.; Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China.; School of Environment Science and Engineering, Dalian Maritime University, Dalian 116026, China.; School of Food Science and Engineering, Dalian Ocean University, Dalian 116023, China.; Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China. Electronic address: yinheng@dicp.ac.cn.
To investigate the effect and mechanism of chitosan nanoparticles (CSNPs) on the germination and seedling growth of wheat (Triticum aestivum L.), we conducted systematic research on the impact of different concentrations (1-100mug/mL) of CSNPs and chitosan (CS). The result of energy-dispersive spectroscopy (EDS) and confocal laser scanning microscopy (CLSM) showed that adsorption of CSNPs on the surface of wheat seeds was higher than that of CS. CSNPs had growth promoting effect at a lower concentration (5mug/mL) compared with CS (50mug/mL). In addition, the application of 5mug/mL CSNPs induced the auxin-related gene expression, accelerated indole-3-acetic acid (IAA) biosynthesis and transport, and reduced IAA oxidase activity resulting in the increase of IAA concentration in wheat shoots and roots. The results suggest that CSNPs have positive effect on seed germination and seedling growth of wheat at a lower concentration than CS due to higher adsorption on the surface of wheat seeds.
PMID: 30557637
J Integr Plant Biol , IF:4.885 , 2019 Apr , V61 (4) : P406-416 doi: 10.1111/jipb.12713
Rice miR394 suppresses leaf inclination through targeting an F-box gene, LEAF INCLINATION 4.
National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, the Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.; University of the Chinese Academy of Sciences, Beijing 100049, China.
Rice leaf inclination is an important agronomic trait, closely related to plant architecture and yield. Identification of genes controlling leaf inclination would assist in crop improvement. Although various factors, including the plant hormones auxin and brassinosteroids, have been shown to regulate lamina joint development, the role of microRNAs in regulating leaf inclination remains largely unknown. Here, we functionally characterize the role of rice miR394 and its target, LEAF INCLINCATION 4 (LC4), which encodes an F-box protein, in the regulation of leaf inclination. We show that miR394 and LC4 work, antagonistically, to regulate leaf lamina joint development and rice architecture, by modulating expansion and elongation of adaxial parenchyma cells. Suppressed expression of miR394, or enhanced expression of LC4, results in enlarged leaf angles, whereas reducing LC4 expression by CRISPR/Cas9 leads to reduced leaf inclination, suggesting LC4 as candidate for use in rice architecture improvement. LC4 interacts with SKP1, a component of the SCF E3 ubiquitin ligase complex, and transcription of both miR394 and LC4 are regulated by auxin. Rice plants with altered expression of miR394 or LC4 have altered auxin responses, indicating that the miR394-LC4 module mediates auxin effects important for determining rice leaf inclination and architecture.
PMID: 30144351
Ecotoxicol Environ Saf , IF:4.872 , 2019 Apr , V171 : P683-690 doi: 10.1016/j.ecoenv.2019.01.035
Effects of elevated ultraviolet-B radiation on root growth and chemical signaling molecules in plants.
State Key Laboratory of Food Science and Technology, Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China.; State Key Laboratory of Food Science and Technology, Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China; Jiangsu Cooperative Innovation Center of Water Treatment Technology and Materials, Suzhou University of Science and Technology, Suzhou 215009, China. Electronic address: qingzhou510@yahoo.com.; Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, Jiangsu Key Laboratory of Biomedical Materials, School of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210046, China. Electronic address: huangxiaohuanjnu@yahoo.com.
Ozone layer depletion leads to elevated ultraviolet-B (UV-B) radiation, which affects plant growth; however, little is known about the relationship between root growth and signaling molecules in roots. Therefore, in this work, simulated UV-B radiation was used to study the effects of elevated UV-B radiation on root growth of soybean seedlings and changes in the content of signaling molecules in roots. The results showed that compared with the control, the 2.63kJm(-2) d(-1) and 6.17kJm(-2) d(-1) elevated UV-B radiation treatments inhibited root growth, and root growth parameters (total root length, root surface area, root volume, average diameter, root tip number, and root dry weight) all decreased. For root signaling molecules, the content of nitric oxide, reactive oxygen species, abscisic acid, salicylic acid, and jasmonic acid increased, and the content of auxin, cytokinin, and gibberellin decreased. The above indices changed more significantly under the 6.17kJm(-2) d(-1) treatment. After withdrawal of the exposure, the above indices could be restored to a certain extent. These data indicated that UV-B radiation interfered with root growth by affecting the content of signaling molecules in roots, and the degree of the effects was related to the intensity of UV-B radiation. The results from this study provide a theoretical basis for studying the preliminary mechanism of elevated UV-B radiation on root growth and possible pathways that can mitigate UV-B radiation damage for root growth. ONE SENTENCE SUMMARY: The effects of elevated UV-B on root growth of soybean seedlings were regulated by signaling molecules, and the degree of the effects was related to the intensity of UV-B radiation.
PMID: 30658304
Ecotoxicol Environ Saf , IF:4.872 , 2019 Apr , V171 : P301-312 doi: 10.1016/j.ecoenv.2018.12.084
New insight into the molecular basis of cadmium stress responses of wild paper mulberry plant by transcriptome analysis.
Hunan Research Center of Engineering Technology for Utilization of Environmental and Resources Plant, Central South University of Forestry and Technology, 498 Shaoshan South Road, 410004 Changsha, Hunan Province, China; School of Material and Chemical Engineering, Hunan City University, 518 Yingbin Road, 413000 Yiyang, Hunan Province, China.; School of Material and Chemical Engineering, Hunan City University, 518 Yingbin Road, 413000 Yiyang, Hunan Province, China.; Hunan Research Center of Engineering Technology for Utilization of Environmental and Resources Plant, Central South University of Forestry and Technology, 498 Shaoshan South Road, 410004 Changsha, Hunan Province, China. Electronic address: zyl8291290@163.com.; Laboratory of Walnut Research Center, College of Forestry, Northwest A & F University, Yangling 712100 Shaanxi, China. Electronic address: yangguiyan@nwsuaf.edu.cn.
BACKGROUND: Heavy metal contamination is becoming a limitation to the utilization of soil and the distribution of vegetation. In particular, cadmium (Cd) pollution has had a serious impact on the food chain. Broussonetia papyrifera is a widely distributed pioneer tree species of heavy metal contaminated areas with important economic value. However, little is known about the genomic background of the Cd-tolerance mechanism in B. papyrifera. RESULTS: The CdCl2 responsive physiology was evaluated and proved to be involved in antioxidase activity and active oxygen species (ROS) accumulation. The leaf and root transcriptomes derived from B. papyrifera grown under normal and CdCl2 stress conditions were systematically investigated using the Illumina HiSeq method. A total of 180,678,660bp (27.1GB) clean reads were assembled into 589,487 high-quality unigenes, of which 256,025 (43.43% of the total) and 250,251 (42.45% of the total) were aligned in Gene Ontology (GO) and Protein family (Pfam), respectively. A total of 24,414 differentially expressed genes (DEGs) were GO-annotated into 53, 23, 55, and 60 terms from the transcriptomes of root and leaf tissues under Cd stress and control conditions. A total of 117,547 Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology (KO)-annotated DEGs were enriched in at least 47 KEGG pathway terms among the four comparisons. Many genes encoding important transcription factors (e.g., auxin/indole-3-acetic acid (AUX/IAA), basic helix-loop-helix (bHLH), DNA-binding one zinc finger (Dof), and MYB) and proteins involved in plant-pathogen interactions, phenylpropanoid biosynthesis, plant hormone signal transduction, oxidative phosphorylation, carbon fixation, peroxisomes, flavonoid biosynthesis, and glutathione metabolism, among others, were substantially upregulated under CdCl2 stress. CONCLUSIONS: These genes represent important candidates for studying Cd-response mechanisms and molecular biology of B. papyrifera and related species. Our findings provide a genomic sequence resource for functional genetic assignments in B. papyrifera, which will help elucidate the molecular mechanisms of its Cd-stress responses and facilitate the bioremediation of heavy metal contaminated areas via breeding of new stress-tolerant cultivars.
PMID: 30612018
Ecotoxicol Environ Saf , IF:4.872 , 2019 Apr , V170 : P338-345 doi: 10.1016/j.ecoenv.2018.11.108
Effects of organic molecules from biochar-extracted liquor on the growth of rice seedlings.
Liaoning Biochar Engineering & Technology Research Center, Shenyang Agricultural University, Shenyang 110866, PR China.; Zunyi Normal College, Zunyi 863002, PR China.; Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Key Laboratory of Plant Nutrition and Fertilizer, Ministry of Agriculture, Beijing 100081, PR China.; Ultrasonography Laboratory, The First Affiliated Hospital of Dalian Medical University, Dalian 116011, PR China.; Liaoning Biochar Engineering & Technology Research Center, Shenyang Agricultural University, Shenyang 110866, PR China. Electronic address: 254078756@qq.com.
There are many reports indicating that biochar can promote growth; however, its mechanism of action remains unclear. The aim of this study was to show that organic molecules from biochar-extracted liquor affect the growth of rice seedlings. In this study, rice seedlings were cultured under water. Agronomic traits and growth-related genes and proteins were used as markers to describe more precisely the effects of biochar on specific growth parameters of rice seedlings. Our results demonstrated that the 3% biochar-extracted liquor amendment clearly promoted growth. The growth-related gene auxin binding protein 1 and its encoded protein were up-regulated. Molecular simulations revealed that 2-acetyl-5-methylfuran from biochar-extracted liquor could interact with auxin binding protein 1 in a similar way to indoleacetic acid binding. The growth of rice seedlings was therefore affected by biochar-extracted liquor, which acted on the ABP1 signalling pathway.
PMID: 30544094
PLoS Comput Biol , IF:4.7 , 2019 Apr , V15 (4) : Pe1006896 doi: 10.1371/journal.pcbi.1006896
Toward a 3D model of phyllotaxis based on a biochemically plausible auxin-transport mechanism.
Institute of Plant Sciences, University of Bern, Bern, Switzerland.; Universite Clermont Auvergne, INRA, PIAF, Clermont-Ferrand, France.
Polar auxin transport lies at the core of many self-organizing phenomena sustaining continuous plant organogenesis. In angiosperms, the shoot apical meristem is a potentially unique system in which the two main modes of auxin-driven patterning-convergence and canalization-co-occur in a coordinated manner and in a fully three-dimensional geometry. In the epidermal layer, convergence points form, from which auxin is canalized towards inner tissue. Each of these two patterning processes has been extensively investigated separately, but the integration of both in the shoot apical meristem remains poorly understood. We present here a first attempt of a three-dimensional model of auxin-driven patterning during phyllotaxis. We base our simulations on a biochemically plausible mechanism of auxin transport proposed by Cieslak et al. (2015) which generates both convergence and canalization patterns. We are able to reproduce most of the dynamics of PIN1 polarization in the meristem, and we explore how the epidermal and inner cell layers act in concert during phyllotaxis. In addition, we discuss the mechanism by which initiating veins connect to the already existing vascular system.
PMID: 30998674
Int J Mol Sci , IF:4.556 , 2019 Apr , V20 (9) doi: 10.3390/ijms20092079
Development-Related miRNA Expression and Target Regulation during Staggered In Vitro Plant Regeneration of Tuxpeno VS-535 Maize Cultivar.
Departamento de Bioquimica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, 04510 Ciudad de Mexico, CDMX, Mexico. ana_bell_89@hotmail.com.; Departamento de Bioquimica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, 04510 Ciudad de Mexico, CDMX, Mexico. vasti.juarez.gonzalez@gmail.com.; Jardin Botanico, Instituto de Biologia, Universidad Nacional Autonoma de Mexico, 04510 Ciudad de Mexico, CDMX, Mexico. esz@ib.unam.mx.; Departamento de Bioquimica, Facultad de Quimica, Universidad Nacional Autonoma de Mexico, 04510 Ciudad de Mexico, CDMX, Mexico. cesy@unam.mx.
In vitro plant regeneration addresses basic questions of molecular reprogramming in the absence of embryonic positional cues. The process is highly dependent on the genotype and explant characteristics. However, the regulatory mechanisms operating during organ differentiation from in vitro cultures remain largely unknown. Recently, miRNAs have emerged as key regulators during embryogenic callus induction, plant differentiation, auxin responses and totipotency. Here, we explored how development-related miRNA switches the impact on their target regulation depending on physiological and molecular events taking place during maize Tuxpeno VS-535 in vitro plant regeneration. Three callus types with distinctive regeneration potential were characterized by microscopy and histological preparations. The embryogenic calli (EC) showed higher miRNA levels than non-embryogenic tissues (NEC). An inverse correlation for miR160 and miR166 targets was found during EC callus induction, whereas miR156, miR164 and miR394 displayed similar to their targets RNA accumulation levels. Most miRNA accumulation switches took place early at regenerative spots coincident with shoot apical meristem (SAM) establishment, whereas miR156, miR160 and miR166 increased at further differentiation stages. Our data uncover particular miRNA-mediated regulation operating for maize embryogenic tissues, supporting their regulatory role in early SAM establishment and basipetala growth during the in vitro regeneration process.
PMID: 31035580
Int J Mol Sci , IF:4.556 , 2019 Apr , V20 (8) doi: 10.3390/ijms20081836
Strigolactones Promote Leaf Elongation in Tall Fescue through Upregulation of Cell Cycle Genes and Downregulation of Auxin Transport Genes in Tall Fescue under Different Temperature Regimes.
College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China. qnanhu@gmail.com.; Department of Plant Biology and Pathology, Rutgers, the State University of New Jersey, New Brunswick, NJ 08901, USA. qnanhu@gmail.com.; College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China. sxzhang@nwafu.edu.cn.; Department of Plant Biology and Pathology, Rutgers, the State University of New Jersey, New Brunswick, NJ 08901, USA. huang@aesop.rutgers.edu.
Strigolactones (SLs) have recently been shown to play roles in modulating plant architecture and improving plant tolerance to multiple stresses, but the underlying mechanisms for SLs regulating leaf elongation and the influence by air temperature are still unknown. This study aimed to investigate the effects of SLs on leaf elongation in tall fescue (Festuca arundinacea, cv. 'Kentucky-31') under different temperature regimes, and to determine the interactions of SLs and auxin in the regulation of leaf growth. Tall fescue plants were treated with GR24 (synthetic analog of SLs), naphthaleneacetic acid (NAA, synthetic analog), or N-1-naphthylphthalamic acid (NPA, auxin transport inhibitor) (individually and combined) under normal temperature (22/18 degrees C) and high-temperature conditions (35/30 degrees C) in controlled-environment growth chambers. Exogenous application of GR24 stimulated leaf elongation and mitigated the heat inhibition of leaf growth in tall fescue. GR24-induced leaf elongation was associated with an increase in cell numbers, upregulated expression of cell-cycle-related genes, and downregulated expression of auxin transport-related genes in elongating leaves. The results suggest that SLs enhance leaf elongation by stimulating cell division and interference with auxin transport in tall fescue.
PMID: 31013928
Int J Mol Sci , IF:4.556 , 2019 Apr , V20 (8) doi: 10.3390/ijms20081947
Defining the Genetic Basis of Plant(-)Endophytic Bacteria Interactions.
Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 40-032 Katowice, Poland. apinski@us.edu.pl.; Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 40-032 Katowice, Poland. alexander.betekhtin@us.edu.pl.; Department of Biochemistry, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 40-032 Katowice, Poland. katarzyna.hupert-kocurek@us.edu.pl.; Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Penglais Campus, Aberystwyth, Wales SY23 3DA, UK. lum@aber.ac.uk.; Department of Plant Anatomy and Cytology, Faculty of Biology and Environmental Protection, University of Silesia in Katowice, 40-032 Katowice, Poland. robert.hasterok@us.edu.pl.
Endophytic bacteria, which interact closely with their host, are an essential part of the plant microbiome. These interactions enhance plant tolerance to environmental changes as well as promote plant growth, thus they have become attractive targets for increasing crop production. Numerous studies have aimed to characterise how endophytic bacteria infect and colonise their hosts as well as conferring important traits to the plant. In this review, we summarise the current knowledge regarding endophytic colonisation and focus on the insights that have been obtained from the mutants of bacteria and plants as well as 'omic analyses. These show how endophytic bacteria produce various molecules and have a range of activities related to chemotaxis, motility, adhesion, bacterial cell wall properties, secretion, regulating transcription and utilising a substrate in order to establish a successful interaction. Colonisation is mediated by plant receptors and is regulated by the signalling that is connected with phytohormones such as auxin and jasmonic (JA) and salicylic acids (SA). We also highlight changes in the expression of small RNAs and modifications of the cell wall properties. Moreover, in order to exploit the beneficial plant-endophytic bacteria interactions in agriculture successfully, we show that the key aspects that govern successful interactions remain to be defined.
PMID: 31010043
Int J Mol Sci , IF:4.556 , 2019 Apr , V20 (7) doi: 10.3390/ijms20071788
Effects of Naphthazarin (DHNQ) Combined with Lawsone (NQ-2-OH) or 1,4-Naphthoquinone (NQ) on the Auxin-Induced Growth of Zea mays L. Coleoptile Segments.
Department of Plant Physiology, Faculty of Biology and Environmental Protection, University of Silesia, Jagiellonska 28, PL-40032 Katowice, Poland. malgorzata.rudnicka@us.edu.pl.; Department of Plant Physiology, Faculty of Biology and Environmental Protection, University of Silesia, Jagiellonska 28, PL-40032 Katowice, Poland. michal.ludynia@us.edu.pl.; Department of Plant Physiology, Faculty of Biology and Environmental Protection, University of Silesia, Jagiellonska 28, PL-40032 Katowice, Poland. waldemar.karcz@us.edu.pl.
Naphthoquinones, plants secondary metabolites are known for their antibacterial, antifungal, anti-inflammatory, anti-cancer and anti-parasitic properties. The biological activity of naphthoquinones is connected with their ability to generate reactive oxygen species and to modify biological molecules at their nucleophilic sites. In our research, the effect of naphthazarin (DHNQ) combined with 2-hydroxy-1,4-naphthoquinone (NQ-2-OH) or 1,4-naphthoquinone (1,4-NQ) on the elongation growth, pH changes of the incubation medium, oxidative stress and redox activity of maize coleoptile cells were investigated. This paper describes experiments performed with maize (Zea mays L.) coleoptile segments, which is a classical model system to study plant cell elongation growth. The data presented clearly demonstrate that lawsone and 1,4-naphthoquinone combined with naphthazarin, at low concentrations (1 and 10 nM), reduced the endogenous and IAA-induced (Indole-3-Acetic Acid) elongation growth of maize coleoptile segments. Those changes in growth correlated with the proton concentration in the incubation medium, which suggests that the changes in the growth of maize coleoptile segments observed in the presence of naphthoquinones are mediated through the activity of PM H(+)-ATPase. The presence of naphthoquinones induced oxidative stress in the maize coleoptile tissue by producing hydrogen peroxide and causing changes in the redox activity. Moreover, the incubation of maize segments with both naphthoquinones combined with naphthazarin resulted in lipid peroxidation and membrane damage. The regulation of PM H(+)-ATPase activity, especially its inhibition, may result from two major types of reaction: first, a direct interaction between an enzyme and naphthoquinone, which leads to the covalent modification of the protein thiols and the generation of thioethers, which have been found to alter the activity of the PM H(+)-ATPases; second, naphthoquinones induce reactive oxygen species (ROS) production, which inhibits PM H(+)-ATPases by increasing cytosolic Ca(2+). This harmful effect was stronger when naphthazarin and 1,4-naphthoquinone were added together. Taking these results into account, it can be suggested that by combining naphthoquinones in small quantities, an alternative to synthetic pesticides could be developed.
PMID: 30978914
Int J Mol Sci , IF:4.556 , 2019 Apr , V20 (7) doi: 10.3390/ijms20071735
The Role of Melatonin in Salt Stress Responses.
Shandong Provincial Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, China. 18363850217@163.com.; Shandong Provincial Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, China. m15168849563@163.com.; Shandong Provincial Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, China. m15953147572@163.com.; Shandong Provincial Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, China. 17354609629@163.com.; Shandong Provincial Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, China. 18753135561@163.com.; Shandong Provincial Key Laboratory of Plant Stress Research, College of Life Science, Shandong Normal University, Jinan 250014, China. chenminrundong@sdnu.edu.cn.
Melatonin, an indoleamine widely found in animals and plants, is considered as a candidate phytohormone that affects responses to a variety of biotic and abiotic stresses. In plants, melatonin has a similar action to that of the auxin indole-3-acetic acid (IAA), and IAA and melatonin have the same biosynthetic precursor, tryptophan. Salt stress results in the rapid accumulation of melatonin in plants. Melatonin enhances plant resistance to salt stress in two ways: one is via direct pathways, such as the direct clearance of reactive oxygen species; the other is via an indirect pathway by enhancing antioxidant enzyme activity, photosynthetic efficiency, and metabolite content, and by regulating transcription factors associated with stress. In addition, melatonin can affect the performance of plants by affecting the expression of genes. Interestingly, other precursors and metabolite molecules associated with melatonin can also increase the tolerance of plants to salt stress. This paper explores the mechanisms by which melatonin alleviates salt stress by its actions on antioxidants, photosynthesis, ion regulation, and stress signaling.
PMID: 30965607
Int J Mol Sci , IF:4.556 , 2019 Apr , V20 (7) doi: 10.3390/ijms20071705
Effects of High Temperature on Embryological Development and Hormone Profile in Flowers and Leaves of Common Buckwheat (Fagopyrum esculentum Moench).
Department of Plant Physiology, University of Agriculture, Podluzna 3, 30-239 Krakow, Poland. rrplazek@cyf-kr.edu.pl.; Department of Plant Cytology and Embryology, Jagiellonian University, Gronostajowa 9, 30(-)387 Krakow, Poland. aneta.slomka@uj.edu.pl.; Polish Academy of Sciences, Institute of Plant Physiology, Niezapominajek 21, 30-239 Krakow, Poland. przemyslawkopec@gmail.com.; Polish Academy of Sciences, Institute of Plant Physiology, Niezapominajek 21, 30-239 Krakow, Poland. m.dziurka@ifr-pan.krakow.pl.; Department of Plant Physiology, University of Agriculture, Podluzna 3, 30-239 Krakow, Poland. marta.golebiewska@gmail.com.; Department of Plant Cytology and Embryology, Jagiellonian University, Gronostajowa 9, 30(-)387 Krakow, Poland. klaudia.michno@doctoral.uj.edu.pl.; Department of Plant Physiology, University of Agriculture, Podluzna 3, 30-239 Krakow, Poland. kubapaaa@gmail.com.; Polish Academy of Sciences, Institute of Plant Physiology, Niezapominajek 21, 30-239 Krakow, Poland. dubert@ifr-pan.edu.pl.
Common buckwheat is a valuable crop, mainly due to the beneficial chemical composition of its seeds. However, buckwheat cultivation is limited because of unstable seed yield. The most important reasons for the low yield include embryo and flower abortion. The aim of this work is to verify whether high temperature affects embryological development in this plant species. The experiment was conducted on plants of a Polish cultivar 'Panda' and strain PA15, in which the percentage of degenerating embryo sacs was previously determined and amounted to 32% and 10%, respectively. The plants were cultivated in phytotronic conditions at 20 degrees C (control), and 30 degrees C (thermal stress). The embryological processes and hormonal profiles in flowers at various developmental stages (buds, open flowers, and wilted flowers) and in donor leaves were analyzed in two-month-old plants. Significant effects of thermal stress on the defective development of female gametophytes and hormone content in flowers and leaves were observed. Ovules were much more sensitive to high temperature than pollen grains in both genotypes. Pollen viability remained unaffected at 30 degrees C in both genotypes. The effect of temperature on female gametophyte development was visible in cv. Panda but not in PA15 buds. A drastic reduction in the number of properly developed embryo sacs was clear in open flowers at 30 degrees C in both genotypes. A considerable increase in abscisic acid in open flowers ready for fertilization may serve as a signal inducing flower senescence observed in the next few days. Based on embryological analyses and hormone profiles in flowers, we conclude that cv. 'Panda' is more sensitive to thermal stress than strain PA15, mainly due to a much earlier response to thermal stress involving impairment of embryological processes already in the flower buds.
PMID: 30959807
Aquat Toxicol , IF:4.344 , 2019 Apr , V209 : P1-12 doi: 10.1016/j.aquatox.2019.01.015
2,4-Dichlorophenoxyacetic acid containing herbicide impairs essential visually guided behaviors of larval fish.
Department of Integrative Biology, University of Wisconsin - Madison, Madison, WI, USA.; Department of Forest and Wildlife Ecology, University of Wisconsin - Madison, Madison, WI, USA.; Department of Integrative Biology, University of Wisconsin - Madison, Madison, WI, USA. Electronic address: mawolman@wisc.edu.
Aquatic herbicides are used worldwide to eradicate nuisance and invasive plants despite limited knowledge of their toxicity to non-target organisms. 2,4-Dichlorophenoxyacetic acid (2,4-D) is a common active ingredient in commercial herbicide formulations, which triggers plant cell death by mimicking the plant-specific hormone auxin. Application practices of 2,4-D commercial herbicides typically coincide with yearly freshwater fish spawning periods. This practice exposes fish to xenobiotics at their vulnerable larval stages. The full impacts of 2,4-D on larval fish remains poorly understood, and hence, whether it may alter larval survival, larval behavior, fish populations, and ecosystem dynamics. In the present study, we exposed embryonic and larval zebrafish (Danio rerio) to the active ingredient 2,4-D (pure 2,4-D) or a 2,4-D containing commercial herbicide DMA4((R))IVM (DMA4) and evaluated morphology, survival, behavior, and nervous system function. At 2,4-D concentrations producing no overt morphological defects during embryonic or early larval stages, we observed reduced survival throughout a 21-day larval assay (4-8 ppm DMA4 and 0.75-4 ppm pure 2,4-D). Notably, prey capture, a behavior essential to survival, was reduced in 2,4-D-exposed larval zebrafish (4-8 ppm DMA4 and 0.75-4 ppm pure 2,4-D) and yellow perch (Perca flavescens) (4-20 ppm DMA4). In zebrafish, 8 ppm DMA4 exposure reduced prey capture when exposure was restricted to the period of visual system development. Consistent with these results, larval zebrafish exposed to 8 ppm DMA4 showed reduced neural activity within the optic tectum following prey exposure. Together, our results suggest that 2,4-D alters the development and function of neural circuits underlying vision of larval fish, and thereby reduces visually guided behaviors required for survival.
PMID: 30684730
Physiol Plant , IF:4.148 , 2019 Apr , V165 (4) : P671-672 doi: 10.1111/ppl.12939
New tools for engineering tomorrow's forests.
Department of Plant Physiology, Umea University, 907 36 Umea, Sweden.
It is difficult to overstate the role of wood in the story of humanity. In times that predate recorded history it provided shelter from the elements, light and warmth when burned, and a supple material with which early humans could craft their first tools. Today, it is still one of our chief building materials and an emerging industry is extending its applications through the development of novel biomaterials, such as cellulose fiber-derived nanocomposites. An article in this issue of Physiologia Plantarum (Johnsson et al. 2019) describes the influence the phytohormones auxin and gibberellic acid (GA) have on the process of wood formation, and reveals possible targets for optimizing cell wall properties in fiber cells.
PMID: 30919994
Physiol Plant , IF:4.148 , 2019 Apr , V165 (4) : P800-813 doi: 10.1111/ppl.12784
Transcriptome profiling of yellow leafy head development during the heading stage in Chinese cabbage (Brassica rapa subsp. pekinensis).
Liaoning Engineering Research Center of Meat Processing and Quality Safety Control, Department of Food Science and Engineering, Jinzhou Medical University, Jinzhou 121000, China.; Liaoning Research Institute of Cash Crops, Liaoyang 111000, China.
The yellow leafy head of Brassica rapa is known to be tasty and nutritional. Therefore, the heading stage of leaf development is critical to realize high yield and economic benefits. A widely planted commercial cultivar of B. rapa ('Qiubao', deep yellow leafy head) was used to conduct transcriptome analysis. The results showed that the yellowing of the inner leaf was likely induced by the predominant beta-carotene biosynthesis pathway due to the upregulated gene geranylgeranyl diphosphate and phytoene synthase, and the downregulated gene CrtL-e, NCED4 and DWARF-27. Some genes related to chlorophyll synthesis were also found to be downregulated, such as nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase and protochlorophyllide reductase A. Transcript profiling also revealed strong changes in expression levels of hormonal genes related to auxin, cytokinin, ethylene, abscisic acid, gibberellin and brassinosteroids, suggesting the crucial role that hormones play in heading stage. Examination of carbohydrate and sucrose metabolism pathways revealed that sucrose biosynthesis is probably regulated by 6-phosphofructokinase and sucrose synthase 1 (SUS1/SuSy1) branch, instead of the sucrose-phosphate synthase branch. Several cold-response genes were induced in the late-heading stage, but the results suggest that the common C-repeat binding factor responsive pathway may not be involved in cold adaption. We also identified a series of upregulated transcription factors-AP2/ERF, MYB, bHLH, NAC and WRKY were found to be predominant. The transcripts analysis provides a preliminary genetic resource to unravel key genes and molecular mechanisms responsible for leafy head development in B. rapa, therefore, improving leafy head quality and yield through genetic means in future.
PMID: 29900559
Physiol Plant , IF:4.148 , 2019 Apr , V165 (4) : P768-779 doi: 10.1111/ppl.12770
Gibberellins modulate auxin responses during tomato (Solanum lycopersicum L.) fruit development.
Instituto de Botanica del Nordeste (IBONE), UNNE-CONICET, 3400 Corrientes, Argentina.; Facultad de Ciencias Agrarias, UNNE, 3400 Corrientes, Argentina.; Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali, Universita di Pisa, 56124 Pisa, Italy.
In tomato, auxin and gibberellins (GAs) interact with each other to drive fruit growth and development. While the role of auxin in directing GA biosynthesis and signal is already known, very little information has been obtained about GA-mediated control of auxin signalling and response. Interestingly, we show that gibberellic acid (GA3 ) is able to modify the expression of several auxin signalling genes in the partial auxin-insensitive diageotropica (dgt) mutant, suggesting that GAs may override the control of DGT on auxin signal. Procera (pro) mutation, which confers a constitutively active GA signal, enhances the effects of exogenous auxin, indicating that PRO may act as a negative effector of auxin responses in fruits. Indeed, transcript modulation of some auxin/indole acetic acid and auxin response factor genes in auxin-treated dgt/pro fruits suggests that PRO controls their expression possibly bypassing DGT. It was also shown that GA biosynthesis, in response to auxin treatment, is largely controlled by DGT. It is therefore conceivable that the DGT-mediated increase of active GAs in auxin-treated or pollinated fruits would promote PRO degradation, which in turn activates part of the auxin signalling cascade.
PMID: 29888535
Physiol Plant , IF:4.148 , 2019 Apr , V165 (4) : P673-689 doi: 10.1111/ppl.12766
The plant hormone auxin directs timing of xylem development by inhibition of secondary cell wall deposition through repression of secondary wall NAC-domain transcription factors.
Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea, Sweden.; Stora Enso AB, Falun, Sweden.
Wood formation in higher plants is a complex and costly developmental process regulated by a complex network of transcription factors, short peptide signals and hormones. Correct spatiotemporal initiation of differentiation and downstream developmental stages is vital for proper wood formation. Members of the NAC (NAM, ATAF1/2 and CUC) family of transcription factors are described as top level regulators of xylem cell fate and secondary cell wall (SCW) deposition, but the signals initiating their transcription have yet to be elucidated. We found that treatment of Populus stems with auxin repressed transcription of NAC transcription factors associated with fiber and SCW formation and induced vessel-specific NACs, whereas gibberellic acid (GA) induced the expression of both classes of NAC domain transcription factors involved in wood formation. These transcriptional changes were reflected in alterations of stem anatomy, i.e. auxin treatment reduced cell wall thickness, whereas GA had a promotive effect on SCW deposition and on the rate of wood formation. Similar changes were observed on treatment of Arabidopsis thaliana stems with GA or the synthetic auxin NAA. We also observed corresponding changes in PIN5 overexpressing lines, where interference with auxin transport leads to premature SCW deposition and formation of additional fiber bundles. Together, this suggests wood formation is regulated by an integrated readout of both auxin and GA, which, in turn, controls expression of fiber and vessel specific NACs.
PMID: 29808599
Biochem J , IF:4.097 , 2019 Apr , V476 (7) : P1105-1107 doi: 10.1042/BCJ20190060
Plant nitrilase: a new job for an old enzyme.
Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, U.S.A. jjez@wustl.edu.
Nitrilases are versatile enzymes that hydrolyze nitriles to carboxylic acids and ammonia, but many members of this family lack defined biological functions. In plants, nitrilases have been associated with detoxification of cyanide-containing compounds and auxin biosynthesis; however, recent work suggests that the chemical versatility of these proteins contributes to metabolite repair. In this issue of the Biochemical Journal, Niehaus et al. demonstrate that the Nit1 nitrilase from Arabidopsis thaliana functions as a metabolite repair enzyme that removes deaminated glutathione from the cytoplasm and plastids.
PMID: 30971459
Biomolecules , IF:4.082 , 2019 Apr , V9 (5) doi: 10.3390/biom9050167
Integrated Transcriptomic, Proteomic, and Metabolomics Analysis Reveals Peel Ripening of Harvested Banana under Natural Condition.
South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China. yunze@scbg.ac.cn.; South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China. litaotao@scbg.ac.cn.; Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China. huijun_gao@aliyun.com.; South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China. zhuhong@scbg.ac.cn.; Department of Chemistry and Biotechnology, ERA Chair of Green Chemistry, School of Science, Tallinn University of Technology, 12618 Tallinn, Estonia. vijai.gupta@ttu.ee.; South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China. ymjiang@scbg.ac.cn.; South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China. xwduan@scbg.ac.cn.
Harvested banana ripening is a complex physiological and biochemical process, and there are existing differences in the regulation of ripening between the pulp and peel. However, the underlying molecular mechanisms governing peel ripening are still not well understood. In this study, we performed a combination of transcriptomic, proteomic, and metabolomics analysis on peel during banana fruit ripening. It was found that 5784 genes, 94 proteins, and 133 metabolites were differentially expressed or accumulated in peel during banana ripening. Those genes and proteins were linked to ripening-related processes, including transcriptional regulation, hormone signaling, cell wall modification, aroma synthesis, protein modification, and energy metabolism. The differentially expressed transcriptional factors were mainly ethylene response factor (ERF) and basic helix-loop-helix (bHLH) family members. Moreover, a great number of auxin signaling-related genes were up-regulated, and exogenous 3-indoleacetic acid (IAA) treatment accelerated banana fruit ripening and up-regulated the expression of many ripening-related genes, suggesting that auxin participates in the regulation of banana peel ripening. In addition, xyloglucan endotransglucosylase/hydrolase (XTH) family members play an important role in peel softening. Both heat shock proteins (Hsps) mediated-protein modification, and ubiqutin-protesome system-mediated protein degradation was involved in peel ripening. Furthermore, anaerobic respiration might predominate in energy metabolism in peel during banana ripening. Taken together, our study highlights a better understanding of the mechanism underlying banana peel ripening and provides a new clue for further dissection of specific gene functions.
PMID: 31052343
Plant Cell Physiol , IF:4.062 , 2019 Apr , V60 (4) : P802-815 doi: 10.1093/pcp/pcy241
Methane Control of Adventitious Rooting Requires gamma-Glutamyl Cysteine Synthetase-Mediated Glutathione Homeostasis.
College of Life Sciences, Laboratory Center of Life Sciences, Nanjing Agricultural University, Nanjing, China.; Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, China.
Although the key role of methane (CH4) in the induction of cucumber adventitious rooting has been observed previously, the target molecules downstream of the CH4 action are yet to be fully elucidated. Here, we reported that exogenous glutathione (GSH) induced cucumber adventitious root formation; while l-buthionine-sulfoximine (BSO) treatment inhibited it. BSO is a known inhibitor of gamma-glutamyl cysteine synthetase (gamma-ECS), an enzyme involved in GSH biosynthesis. Further investigations showed that endogenous GSH content was rapidly increased by CH4 application, which was correlated with the increased CsGSH1 transcript and gamma-ECS activity. Mimicking the responses of GSH, CH4 could upregulate cell cycle regulatory genes (CsCDC6, CsCDPK1, CsCDPK5 and CsDNAJ-1) and auxin-response genes (CsAux22D-like and CsAux22B-like). Meanwhile, adventitious rooting-related CsmiR160 and CsmiR167 were increased or decreased, respectively, and contrasting tendencies were observed in the changes of their target genes, that included CsARF17 and CsARF8. The responses above were impaired by the removal of endogenous GSH with BSO, indicating that CH4-triggered adventitious rooting was GSH-dependent. Genetic evidence revealed that in the presence of CH4, Arabidopsis mutants cad2 (a gamma-ECS-defective mutant) exhibited, not only the decreased GSH content in vivo, but also the defects in adventitious root formation, both of which were rescued by GSH administration other than CH4. Together, it can be concluded that gamma-ECS-dependent GSH homeostasis might be required for CH4-induced adventitious root formation.
PMID: 30590760
Genes (Basel) , IF:3.759 , 2019 Apr , V10 (4) doi: 10.3390/genes10040290
Overexpression of Nitrate Transporter OsNRT2.1 Enhances Nitrate-Dependent Root Elongation.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China. raymisbah@ymail.com.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China. 2016203044@njau.edu.cn.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China. 2017103097@njau.edu.cn.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China. xinyangzhanlibin@outlook.com.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China. chenjingguang@caas.cn.; CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute in Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen (518000), China. chenjingguang@caas.cn.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, MOA Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China. xiaorongfan@njau.edu.cn.
Root morphology is essential for plant survival. NO(3)(-) is not only a nutrient, but also a signal substance affecting root growth in plants. However, the mechanism of NO(3)(-)-mediated root growth in rice remains unclear. In this study, we investigated the effect of OsNRT2.1 on root elongation and nitrate signaling-mediated auxin transport using OsNRT2.1 overexpression lines. We observed that the overexpression of OsNRT2.1 increased the total root length in rice, including the seminal root length, total adventitious root length, and total lateral root length in seminal roots and adventitious roots under 0.5-mM NO(3)(-) conditions, but not under 0.5-mM NH(4)(+) conditions. Compared with wild type (WT), the (15)NO(3)(-) influx rate of OsNRT2.1 transgenic lines increased by 24.3%, and the expressions of auxin transporter genes (OsPIN1a/b/c and OsPIN2) also increased significantly under 0.5-mM NO(3)(-) conditions. There were no significant differences in root length, ss-glucuronidase (GUS) activity, and the expressions of OsPIN1a/b/c and OsPIN2 in the pDR5::GUS transgenic line between 0.5-mM NO(3)(-) and 0.5-mM NH(4)(+) treatments together with N-1-naphthylphalamic acid (NPA) treatment. When exogenous NPA was added to 0.5-mM NO(3)(-) nutrient solution, there were no significant differences in the total root length and expressions of OsPIN1a/b/c and OsPIN2 between transgenic plants and WT, although the (15)NO(3)(-) influx rate of OsNRT2.1 transgenic lines increased by 25.2%. These results indicated that OsNRT2.1 is involved in the pathway of nitrate-dependent root elongation by regulating auxin transport to roots; i.e., overexpressing OsNRT2.1 promotes an effect on root growth upon NO(3)(-) treatment that requires active polar auxin transport.
PMID: 30970675
Plant Sci , IF:3.591 , 2019 Apr , V281 : P61-71 doi: 10.1016/j.plantsci.2018.12.024
Overexpression of the KNOX gene Tkn4 affects pollen development and confers sensitivity to gibberellin and auxin in tomato.
Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University; Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, 401331 Chongqing, China.; Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, 401331 Chongqing, China.; University of California, Davis, CA 95616.; Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University; Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, 401331 Chongqing, China. Electronic address: zhengguoli@cqu.edu.cn.
The knotted1-like homeobox genes not only regulate the formation and differentiation of meristems and vascular system but are also involved in biosynthesis and signal transduction of diverse plant hormones in tomato. Here, we showed that a knotted1-like homeobox gene Tkn4 is required for pollen and pollen tube growth when this gene is overexpressed in tomato. Pollen grains in the Tkn4 overexpressed plants (Tkn4-OX) germinated quicker than those in the wild-type (WT) plant cultured in vitro in germination media. The percentage of fruit set was higher in Tkn4-OX than in WT plants and the transgenic plants showed an ordered inflorescence. Tkn4-OX seedlings also exhibited sensitivity to gibberellins (GA) and auxins. RNA sequencing results showed that the expression of genes related to sugar, cell wall-modification, microtubule-associated vesicular transport for pollen growth, GA and auxin synthesis were signi fi cantly changed. Hence, Tkn4 contributes to a function in the development of pollen and pollen tube and the regulation of phytohormones to participate in plant growth. These results provided a potential application value for agricultural improvement to enhance the rate of fruit set in tomato.
PMID: 30824062
Plant Sci , IF:3.591 , 2019 Apr , V281 : P159-172 doi: 10.1016/j.plantsci.2019.01.018
Effects of auxin and ethylene on root growth adaptation to different ambient temperatures in Arabidopsis.
Ministry of Education, Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.; National Demonstration Center for Experimental Biology Education, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.; Ministry of Education, Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China. Electronic address: xfli@lzu.edu.cn.
As sessile organisms, plants can modify their growth strategy in response to different temperatures, however very little is known about how roots growth responds to ambient temperature change. Here, we found that high temperature-induced root elongation is dependent on light intensity and the root growth of most TAA1 loss-of-function mutants is more sensitive to higher temperatures in Arabidopsis. TAA1 encodes a tryptophan aminotransferase which involved in the indole-3-pyruvic acid (IPA) pathway of indole-3-acetic acid (IAA) biosynthesis. The root elongation in ckrc1-1(one allele mutant of TAA1) is less sensitive to lower temperatures and more sensitive to higher temperatures than that of Col-0. By comparing the regulatory mechanisms of ckrc1-1 root growth at different temperatures (17 degrees C, 22 degrees C, and 27 degrees C), different interactions between signals (auxin and ethylene) and the effects of downstream genes were observed at different ambient temperatures in Arabidopsis. Lower temperature-enhanced ETR1-mediated ethylene signaling did not promote the expression of CKRC1, while higher temperature-enhanced signaling did. CKRC1 had an important role in the ACC inhibition of cell elongation at 22 degrees C and 27 degrees C but not at 17 degrees C. CKRC1-dependent auxin biosynthesis was critical for maintaining PIN1, PIN2, and AUX1 expression at lower temperatures. CKRC1, AUX1, and PIN2 regulated root elongation by affecting different regions of the root at different temperatures in Arabidopsis. Our experimental results suggested that changes in the in vivo signals at different temperatures were multi-layered in Arabidopsis.
PMID: 30824048
Plant Sci , IF:3.591 , 2019 Apr , V281 : P133-145 doi: 10.1016/j.plantsci.2019.01.027
Transcriptomic and metabolomic analysis of ZmYUC1 mutant reveals the role of auxin during early endosperm formation in maize.
Department of Sustainable Crop Production, Universita Cattolica del Sacro Cuore, Piacenza, Italy. Electronic address: jamila.bernardi@unicatt.it.; Department of Sustainable Crop Production, Universita Cattolica del Sacro Cuore, Piacenza, Italy.; Council for Agricultural Research and Economics, Research Centre for Genomics and Bioinformatics, Fiorenzuola d'Arda, Piacenza, Italy.; Department for Sustainable Food Process, Universita Cattolica del Sacro Cuore, Piacenza, Italy.; Department of Sustainable Crop Production, Universita Cattolica del Sacro Cuore, Piacenza, Italy. Electronic address: adriano.marocco@unicatt.it.
Kernel size in cereal is an important agronomic trait controlled by the interaction of genetic and environmental factors. The endosperm occupies most of the kernel area; for this reason, the endosperm cells dimension, number and metabolic content strongly influence kernel properties. This paper presents the transcriptomic and metabolomic analysis of the maize defective endosperm 18 (de18) mutant, where auxin accumulation in the endosperm is impaired. This mutation, involving the ZmYuc1 gene, leads to a reduced kernel size compared to the wild-type line B37. Our results mainly indicate that IAA concentration controls sugar and protein metabolism during kernel differentiation and it is necessary for BETL formation. Furthermore, a fine tuning of different auxin conjugates is reported as the main mechanism to counteract the auxin deficit. Some candidates as master regulators of endosperm transcriptional regulation mediated by auxin are found between MYB and MADS-box gene families. A link between auxin and storage protein accumulation is highlighted, suggesting that IAA directly or indirectly, through CK or ABA, regulates the transcription of zein coding genes. This study represents a move forward with respect to the current knowledge about the role of auxin during maize endosperm differentiation thus revealing the genes that are modulated by auxin and that control agronomic traits as kernel size and metabolic composition.
PMID: 30824046
Planta , IF:3.39 , 2019 Apr , V249 (4) : P1107-1118 doi: 10.1007/s00425-018-3068-6
Cotyledons contribute to plant growth and hybrid vigor in Arabidopsis.
Faculty of Science, University of Technology, Sydney, NSW, 2007, Australia.; Agriculture and Food, Commonwealth Scientific Industrial Research Organisation, Canberra, ACT, 2601, Australia.; Faculty of Science, University of Technology, Sydney, NSW, 2007, Australia. Liz.Dennis@csiro.au.; Agriculture and Food, Commonwealth Scientific Industrial Research Organisation, Canberra, ACT, 2601, Australia. Liz.Dennis@csiro.au.
MAIN CONCLUSION: In hybrids of Arabidopsis, cotyledons influence the amount and proportion of hybrid vigor in total plant growth. We found Arabidopsis cotyledons are essential for plant growth and in some hybrids for hybrid vigor. In hybrids between C24 and Landsberg erecta (Ler), biomass vigor (heterosis) occurs in the first few days after sowing (DAS), with hybrid cotyledons being larger than those of their parents. C24xLer hybrids are ahead of their parents in activating photosynthesis and auxin pathway genes in cotyledons at 3-4 DAS. "Earliness" is also present in newly emerged C24xLer hybrid leaves. We showed cotyledon removal at 4 DAS caused significant biomass reduction in later growth in hybrids and parental lines. The biomass decrease caused by cotyledon removal can be partially rescued by exogenous sucrose or auxin with different genotypes responding to sucrose and/or auxin differently. Cotyledon removal has different effects on heterosis in different hybrids. After cotyledon removal, in C24xLer hybrids, both growth and heterosis were reduced in similar proportions, but the level of hybrid vigor was reduced as a proportion of growth in C24xColumbia (Col) and ColxLer hybrids. The removal of cotyledons at 4 DAS markedly decreased the level of growth and eliminated the heterotic phenotype of Wassilewskija (Ws)/Ler hybrids. In mutant Ws/Ler hybrids which had a reduced level of photosynthesis in the cotyledons, there was a reduction in plant growth and loss of heterosis. The variation in contribution of cotyledons to heterosis in different hybrids indicates there are multiple pathways to achieve heterotic phenotypes.
PMID: 30552582
Planta , IF:3.39 , 2019 Apr , V249 (4) : P1073-1085 doi: 10.1007/s00425-018-3061-0
Indole-3-acetylaspartate and indole-3-acetylglutamate, the IAA-amide conjugates in the diploid strawberry achene, are hydrolyzed in growing seedlings.
Department of Horticultural Science and Microbial and Plant Genome Institute, University of Minnesota, Alderman Hall, 1970 Folwell Avenue, Saint Paul, MN, 55108, USA.; Department of Horticultural Science and Microbial and Plant Genome Institute, University of Minnesota, Alderman Hall, 1970 Folwell Avenue, Saint Paul, MN, 55108, USA. cohen047@umn.edu.; USDA/ARS Genetic Improvement of Fruit and Vegetables Laboratory, 10300 Baltimore Avenue, Beltsville, MD, 20705, USA. janet.slovin@ars.usda.gov.
MAIN CONCLUSION: Indole-3-acetylaspartate and indole-3-acetylglutamate are the stored auxin amino acid conjugates of the achene of the diploid strawberry and serve as sources of auxin during seedling growth. The edible part of the strawberry, a pseudocarp, has long been known to enlarge in response to auxin produced by the developing achenes, the botanical true fruit. Auxin homeostasis involves a complex interaction between biosynthesis, conjugate formation and hydrolysis, catabolism and transport. Strawberry tissues are capable of synthesizing auxin conjugates, and transcriptome data support the expression of genes involved in IAA conjugate formation and hydrolysis throughout embryo development and subsequent seedling growth. Using a highly sensitive and selective mass spectrometric method, we identified all the low molecular weight indole-auxin amino acid conjugates in achenes of F. vesca as consisting of indole-3-acetylaspartate (IAasp) and indole-3-acetylglutamate (IAglu). In contrast to what has been proposed to occur in Arabidopsis, we determined that IAasp and IAglu are hydrolyzed by seedlings to provide a source of free IAA for growth.
PMID: 30535588
Plant Mol Biol , IF:3.302 , 2019 Apr , V99 (6) : P561-573 doi: 10.1007/s11103-019-00836-8
Downregulation of the auxin transporter gene SlPIN8 results in pollen abortion in tomato.
Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China.; Institute of Horticultural Plants, College of Horticulture, China Agricultural University, Beijing, 100193, People's Republic of China. rschan@cau.edu.cn.
KEY MESSAGE: SlPIN8 is expressed specifically within tomato pollen, and that it is involved in tomato pollen development and intracellular auxin homeostasis. The auxin (IAA) transport protein PIN-FORMED (PIN) plays key roles in various aspects of plant development. The biological role of the auxin transporter SlPIN8 in tomato development remains unclear. Here, we examined the expression pattern of the SlPIN8 gene in vegetative and reproductive organs of tomato. RNA interference (RNAi) transgenic lines specifically silenced for the SlPIN8 gene were generated to identify the role of SlPIN8 in pollen development. We found that SlPIN8 mRNA is expressed specifically within tomato pollen. In the anthers, the highest mRNA expression and beta-glucuronidase (GUS) activity of promoter-SlPIN8-GUS was detected during late stages of anther development, when pollen maturation occurred. The downregulation of SlPIN8 did not drastically affect the vegetative growth of tomato. However, in SlPIN8-RNAi transgenic plants, approximately 80% of the pollen grains were identified to be abnormal and lack viability; they were shriveled and flattened. Furthermore, the downregulation of SlPIN8 affected the gene expression of some anther development-specific proteins. SlPIN8-RNAi transgenic plants induced seedless fruits because of defective pollen function rather than defective female gametophyte function. In addition, SlPIN8 was found to localize to the endoplasmic reticulum, consistent with the changes in the auxin levels of SlPIN8-RNAi lines, whereas the level of free IAA was increased in SlPIN8-overexpressing protoplasts, indicating that SlPIN8 is involved in intracellular auxin homeostasis.
PMID: 30734902
Plants (Basel) , IF:2.762 , 2019 Apr , V8 (4) doi: 10.3390/plants8040091
Functional and Genetic Diversity of Bacteria Associated with the Surfaces of Agronomic Plants.
Department of Microbiology and Molecular Genetics, University of the Punjab, Lahore 54590, Pakistan. basharat.ali.mmg@pu.edu.pk.
The main objective of this study was to evaluate the genetic diversity and agricultural significance of bacterial communities associated with the surfaces of selected agronomic plants (carrot, cabbage and turnip). The bacterial diversity of fresh agricultural produce was targeted to identify beneficial plant microflora or opportunistic human pathogens that may be associated with the surfaces of plants. Bacterial strains were screened in vitro for auxin production, biofilm formation and antibiotic resistance. 16S rRNA gene sequencing confirmed the presence of several bacterial genera including Citrobacter, Pseudomonas, Pantoea, Bacillus, Kluyvera, Lysinibacillus, Acinetobacter, Enterobacter, Serratia, Staphylococcus, Burkholderia, Exiguobacterium, Stenotrophomonas, Arthrobacter and Klebsiella. To address the biosafety issue, the antibiotic susceptibility pattern of strains was determined against different antibiotics. The majority of the strains were resistant to amoxicillin (25 microg) and nalidixic acid (30 microg). Strains were also screened for plant growth-promoting attributes to evaluate their positive interaction with colonized plants. Maximum auxin production was observed with Stenotrophomonas maltophilia MCt-1 (101 microg mL(-1)) and Bacillus cereus PCt-1 (97 microg mL(-1)). Arthrobacter nicotianae Lb-41 and Exiguobacterium mexicanum MCb-4 were strong biofilm producers. In conclusion, surfaces of raw vegetables were inhabited by different bacterial genera. Potential human pathogens such as Bacillus cereus, Bacillus anthracis, Enterobacter cloacae, Enterobacter amnigenus and Klebsiella pneumoniae were also isolated, which makes the biosafety of these vegetable a great concern for the local community. Nevertheless, these microbes also harbor beneficial plant growth-promoting traits that indicated their positive interaction with their host plants. In particular, bacterial auxin production may facilitate the growth of agronomic plants under natural conditions. Moreover, biofilm formation may help bacteria to colonize plant surfaces to show positive interactions with host plants.
PMID: 30987359
Plants (Basel) , IF:2.762 , 2019 Apr , V8 (4) doi: 10.3390/plants8040094
Cytokinin-Dependent Control of GH3 Group II Family Genes in the Arabidopsis Root.
Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza-via dei Sardi, 70(-)00185 Rome, Italy. emanuela.pier@gmail.com.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza-via dei Sardi, 70(-)00185 Rome, Italy. unterholzner.simonjosef@gmail.com.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza-via dei Sardi, 70(-)00185 Rome, Italy. elena.salvi2@gmail.com.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza-via dei Sardi, 70(-)00185 Rome, Italy. svolacchia.noemi@gmail.com.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza-via dei Sardi, 70(-)00185 Rome, Italy. gaia.bertolotti@uniroma1.it.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza-via dei Sardi, 70(-)00185 Rome, Italy. raffaele.delloioio@uniroma1.it.; Dipartimento di Biologia e Biotecnologie, Laboratory of Functional Genomics and Proteomics of Model Systems, Universita di Roma, Sapienza-via dei Sardi, 70(-)00185 Rome, Italy. sabrina.sabatini@uniroma1.it.; Department of Biology, University of Pisa-via L. Ghini, 13(-)56126 Pisa, Italy. riccardo.dimambro@unipi.it.
Abstract: The Arabidopsis root is a dynamic system where the interaction between different plant hormones controls root meristem activity and, thus, organ growth. In the root, a characteristic graded distribution of the hormone auxin provides positional information, coordinating the proliferating and differentiating cell status. The hormone cytokinin shapes this gradient by positioning an auxin minimum in the last meristematic cells. This auxin minimum triggers a cell developmental switch necessary to start the differentiation program, thus, regulating the root meristem size. To position the auxin minimum, cytokinin promotes the expression of the IAA-amido synthase group II gene GH3.17, which conjugates auxin with amino acids, in the most external layer of the root, the lateral root cap tissue. Since additional GH3 genes are expressed in the root, we questioned whether cytokinin to position the auxin minimum also operates via different GH3 genes. Here, we show that cytokinin regulates meristem size by activating the expression of GH3.5 and GH3.6 genes, in addition to GH3.17. Thus, cytokinin activity provides a robust control of auxin activity in the entire organ necessary to regulate root growth.
PMID: 30965632
Mol Biol Rep , IF:1.402 , 2019 Apr , V46 (2) : P1625-1634 doi: 10.1007/s11033-019-04611-2
The roles of Aux/IAA gene family in development of Dendrocalamus sinicus (Poaceae: Bambusoideae) inferred by comprehensive analysis and expression profiling.
Research Institute of Resources Insects, Chinese Academy of Forestry, Bailongsi, Kunming, 650233, Panlong, China.; Research Institute of Resources Insects, Chinese Academy of Forestry, Bailongsi, Kunming, 650233, Panlong, China. yanghanqikm@aliyun.com.
Auxin is an important hormone in many plant developmental processes. In this study, the auxin/indole acetic acid (Aux/IAA) gene family was comprehensively identified using Dendrocalamus sinicus transcriptome data. A total of 26 Aux/IAA genes (DsIAA1-DsIAA26) were mined using four conserved Aux/IAA family motifs (PF02309). They encoded hydrophilic proteins, including one or two nuclear localisation signals. The D. sinicus Aux/IAA proteins were classified into two groups, including seven sister-gene pairs based on their phylogenetic relationships. A phylogenetic tree generated by aligning 108 predicted protein sequences of 26 DsIAAs, 43 PhIAAs (Phyllostachys heterocycla), 29 AtIAAs (Arabidopsis), 31 OsIAAs (Oryza sativa) and 22 PtIAAs (Populus) revealed nine major groups. Among them, four groups, including 96 IAA proteins of all five species, suggested that the genes originated before divergence of monocots and dicots. The expression profiling in different tissues showed that most of the DsIAAs preferentially expressed in leaves and shoots, suggesting their important roles in the development of leaves and shoots in D. sinicus. Continuously high expression of DsIAA3, DsIAA4, DsIAA15, and DsIAA20 may be important for regulating shoot development in D. sinicus. These results provide useful information for further research into the function of Aux/IAA genes in woody sympodial bamboos.
PMID: 30690658
Genetica , IF:1.186 , 2019 Apr , V147 (2) : P185-196 doi: 10.1007/s10709-019-00062-6
Genome-wide identification and expression analysis of the AAAP family in Medicago truncatula.
Key Laboratory of Molecular Cytogenetics and Genetic Breeding of Heilongjiang Province, College of Life Science and Technology, Harbin Normal University, No. 1 of Shida Road, Limin Development Zone, Harbin, 150025, China.; Key Laboratory of Molecular Cytogenetics and Genetic Breeding of Heilongjiang Province, College of Life Science and Technology, Harbin Normal University, No. 1 of Shida Road, Limin Development Zone, Harbin, 150025, China. kaku_2008@163.com.
The amino acid/auxin permease (AAAP) gene family plays an important role in the long-distance amino acid transport pathway and takes part in various stages of plant growth and development. However, little is known about the AAAP gene family in Medicago truncatula. Here, we identified 86 putative MtAAAP family members using genome sequence information. Based on phylogenetic analysis, these MtAAAP genes were categorized into eight distinct subfamilies. The MtAAAP genes were mapped on 8 chromosomes and duplication events appeared widely, with 19 and 21 pairs of MtAAAP genes showing segment and tandem duplication events, respectively. Ratio of Ka/Ks indicated that duplicated genes underwent purifying selection. Analysis of RNA-seq data showed that MtAAAP genes exhibited specific expression patterns among different tissues and abiotic stress, indicating that MtAAAP members were involved in plant developmental regulation and stress responses. Expression patterns of 16 MtAAAP genes under abiotic stress were verified by qRT-PCR. The present study provides a foundation for the functional analysis of MtAAAPs in developmental regulation and stress responses.
PMID: 30905050
Heliyon , 2019 Apr , V5 (4) : Pe01418 doi: 10.1016/j.heliyon.2019.e01418
Verification of miRNAs in ginseng decoction by high-throughput sequencing and quantitative real-time PCR.
School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China.; Guangdong Engineering & Technology Research Center of Topical Precise Drug Delivery System, Guangzhou 510006, china.; School of Basic Courses, Guangdong Pharmaceutical University, Guangzhou 510006, China.
Panax ginseng C. A. Meyer is a precious traditional Chinese medicine that has been clinically used for over thousands of years. In general, ginseng needs to be prepared to ginseng decoction before taking it. MicroRNAs are a class of small (18-24 nt), single-stranded molecules that regulate gene expression at the post-transcriptional level. Considering that ginseng miRNAs may be bioactive compounds, we used Illumina high-throughput sequencing and quantitative real-time PCR (qRT-PCR) to validate the existence of miRNAs in fresh ginseng decoction which have been boiled at high temperature. Our previous studies have demonstrated that there are several miRNAs in fresh ginseng. The roots of fresh Panax ginseng were prepared according to routine methods, from which miRNAs were extracted and sequenced. A total of 43 miRNAs were identified from water decoction by Illumina high-throughput sequencing, belonging to 71 miRNA families. The target genes of these miRNAs were predicted by sequencing, and were annotated by GO, KEGG and Nr databases. The functions of these target genes mainly included plant hormone signal transduction, transcription regulation, macromolecular metabolism and auxin signaling. Nine highly expressed miRNAs (miR159, miR167, miR396, miR166, miR168, miR156, miR165, miR162 and miR394) were verified by qRT-PCR, and the results of Illumina high-throughput sequencing and qRT-PCR were consistent. Results from this study indicate that miRNAs remained stable in P. ginseng after high-temperature boiling. Additionally, Illumina high-throughput sequencing was superior in the acquisition of higher amount of small RNAs.
PMID: 30984884