Nature , IF:42.778 , 2019 Jan , V565 (7740) : P490-494 doi: 10.1038/s41586-018-0839-y
Mobile PEAR transcription factors integrate positional cues to prime cambial growth.
Institute of Biotechnology, HiLIFE/Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland.; Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara, Japan.; The Sainsbury Laboratory, University of Cambridge, Cambridge, UK.; Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan.; Centre for Plant Integrative Biology (CPIB) and School of Biosciences, University of Nottingham, Nottingham, UK.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.; VIB Center for Plant Systems Biology, Ghent, Belgium.; Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands.; Nutrition, Metabolism and Genomics Group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.; Graduate School of Humanities and Sciences, Nara Women's University, Nara, Japan.; Centre for Organismal Studies (COS), Heidelberg University, Heidelberg, Germany.; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan.; Department of Plant Biology, Swedish University of Agricultural Sciences, Uppsala, Sweden.; Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, USA.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium. beryb@psb.vib-ugent.be.; VIB Center for Plant Systems Biology, Ghent, Belgium. beryb@psb.vib-ugent.be.; Laboratory of Biochemistry, Wageningen University, Wageningen, The Netherlands. beryb@psb.vib-ugent.be.; Institute of Biotechnology, HiLIFE/Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland. yrjo.helariutta@slcu.cam.ac.uk.; The Sainsbury Laboratory, University of Cambridge, Cambridge, UK. yrjo.helariutta@slcu.cam.ac.uk.
Apical growth in plants initiates upon seed germination, whereas radial growth is primed only during early ontogenesis in procambium cells and activated later by the vascular cambium(1). Although it is not known how radial growth is organized and regulated in plants, this system resembles the developmental competence observed in some animal systems, in which pre-existing patterns of developmental potential are established early on(2,3). Here we show that in Arabidopsis the initiation of radial growth occurs around early protophloem-sieve-element cell files of the root procambial tissue. In this domain, cytokinin signalling promotes the expression of a pair of mobile transcription factors-PHLOEM EARLY DOF 1 (PEAR1) and PHLOEM EARLY DOF 2 (PEAR2)-and their four homologues (DOF6, TMO6, OBP2 and HCA2), which we collectively name PEAR proteins. The PEAR proteins form a short-range concentration gradient that peaks at protophloem sieve elements, and activates gene expression that promotes radial growth. The expression and function of PEAR proteins are antagonized by the HD-ZIP III proteins, well-known polarity transcription factors(4)-the expression of which is concentrated in the more-internal domain of radially non-dividing procambial cells by the function of auxin, and mobile miR165 and miR166 microRNAs. The PEAR proteins locally promote transcription of their inhibitory HD-ZIP III genes, and thereby establish a negative-feedback loop that forms a robust boundary that demarks the zone of cell division. Taken together, our data establish that during root procambial development there exists a network in which a module that links PEAR and HD-ZIP III transcription factors integrates spatial information of the hormonal domains and miRNA gradients to provide adjacent zones of dividing and more-quiescent cells, which forms a foundation for further radial growth.
PMID: 30626969
Nature , IF:42.778 , 2019 Jan , V565 (7740) : P485-489 doi: 10.1038/s41586-018-0837-0
High levels of auxin signalling define the stem-cell organizer of the vascular cambium.
Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland.; Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland.; Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.; The Sainsbury Laboratory, University of Cambridge, Cambridge, UK.; Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland. AriPekka.Mahonen@helsinki.fi.; Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland. AriPekka.Mahonen@helsinki.fi.
Wood, a type of xylem tissue, originates from cell proliferation of the vascular cambium. Xylem is produced inside, and phloem outside, of the cambium(1). Morphogenesis in plants is typically coordinated by organizer cells that direct the adjacent stem cells to undergo programmed cell division and differentiation. The location of the vascular cambium stem cells and whether the organizer concept applies to the cambium are currently unknown(2). Here, using lineage-tracing and molecular genetic studies in the roots of Arabidopsis thaliana, we show that cells with a xylem identity direct adjacent vascular cambial cells to divide and function as stem cells. Thus, these xylem-identity cells constitute an organizer. A local maximum of the phytohormone auxin, and consequent expression of CLASS III HOMEODOMAIN-LEUCINE ZIPPER (HD-ZIP III) transcription factors, promotes xylem identity and cellular quiescence of the organizer cells. Additionally, the organizer maintains phloem identity in a non-cell-autonomous fashion. Consistent with this dual function of the organizer cells, xylem and phloem originate from a single, bifacial stem cell in each radial cell file, which confirms the classical theory of a uniseriate vascular cambium(3). Clones that display high levels of ectopically activated auxin signalling differentiate as xylem vessels; these clones induce cell divisions and the expression of cambial and phloem markers in the adjacent cells, which suggests that a local auxin-signalling maximum is sufficient to specify a stem-cell organizer. Although vascular cambium has a unique function among plant meristems, the stem-cell organizer of this tissue shares features with the organizers of root and shoot meristems.
PMID: 30626967
Trends Plant Sci , IF:14.416 , 2019 Jan , V24 (1) : P6-9 doi: 10.1016/j.tplants.2018.10.014
Local Auxin Biosynthesis Mediates Plant Growth and Development.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, College of Life Sciences, Shandong University, Qingdao, 266237, Shandong, China; These authors contributed equally to this work.; The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, College of Life Sciences, Shandong University, Qingdao, 266237, Shandong, China. Electronic address: tianhuiyu@sdu.edu.cn.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, China. Electronic address: zhangxs@sdau.edu.cn.; The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, College of Life Sciences, Shandong University, Qingdao, 266237, Shandong, China; State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, Shandong, China. Electronic address: dingzhaojun@sdu.edu.cn.
Auxin is one of the most important plant hormones controlling various aspects of plant growth and development. Here, we highlight three recent papers that shed light on how local auxin biosynthesis contributes to plant growth and development in response to endogenous developmental signals and exogenous environmental cues, such as shade and aluminum stress.
PMID: 30448230
Nucleic Acids Res , IF:11.501 , 2019 Jan , V47 (2) : P883-898 doi: 10.1093/nar/gky1205
AtTrm5a catalyses 1-methylguanosine and 1-methylinosine formation on tRNAs and is important for vegetative and reproductive growth in Arabidopsis thaliana.
College of Plant Science and Technology, HuaZhong Agricultural University, Wuhan 430070, China.; Biomass and Bioenergy Research Centre, HuaZhong Agricultural University, Wuhan 430070, China.; College of Life Science, HuaZhong Agricultural University, Wuhan 430070, China.; National Key Laboratory of Crop Genetic Improvement, HuaZhong Agricultural University, Wuhan 430070, China.; Institute of Biophysics, Chinese Academy of Sciences, China.; School of Biosciences, University of Melbourne, Parkville 3010, VIC, Australia.; Joint International Research Laboratory of Metabolic & Developmental Sciences, Shanghai Jiao Tong University-University of Adelaide Joint Centre for Agriculture and Health, State Key Laboratory of Hybrid Rice, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.; College of Horticulture and Forestry Sciences, HuaZhong Agricultural University, Wuhan 430070, China.
Modified nucleosides on tRNA are critical for decoding processes and protein translation. tRNAs can be modified through 1-methylguanosine (m1G) on position 37; a function mediated by Trm5 homologs. We show that AtTRM5a (At3g56120) is a Trm5 ortholog in Arabidopsis thaliana. AtTrm5a is localized to the nucleus and its function for m1G and m1I methylation was confirmed by mutant analysis, yeast complementation, m1G nucleoside level on single tRNA, and tRNA in vitro methylation. Arabidopsis attrm5a mutants were dwarfed and had short filaments, which led to reduced seed setting. Proteomics data indicated differences in the abundance of proteins involved in photosynthesis, ribosome biogenesis, oxidative phosphorylation and calcium signalling. Levels of phytohormone auxin and jasmonate were reduced in attrm5a mutant, as well as expression levels of genes involved in flowering, shoot apex cell fate determination, and hormone synthesis and signalling. Taken together, loss-of-function of AtTrm5a impaired m1G and m1I methylation and led to aberrant protein translation, disturbed hormone homeostasis and developmental defects in Arabidopsis plants.
PMID: 30508117
Dev Cell , IF:10.092 , 2019 Jan , V48 (1) : P64-75.e5 doi: 10.1016/j.devcel.2018.11.031
Lateral Inhibition by a Peptide Hormone-Receptor Cascade during Arabidopsis Lateral Root Founder Cell Formation.
Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501, Japan; Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.; Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501, Japan; Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan.; Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa, Nagoya 464-8602, Japan.; Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501, Japan.; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.; Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan; Graduate School of Science and Technology, Kobe University, 1-1 Rokkodai, Kobe 657-8501, Japan.; Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.; Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan.; Department of Biology, Graduate School of Science, Kobe University, 1-1 Rokkodai, Kobe 657-8501, Japan. Electronic address: h-fukaki@port.kobe-u.ac.jp.
In plants, the position of lateral roots (LRs) depends on initiation sites induced by auxin. The domain of high auxin response responsible for LR initiation stretches over several cells, but only a pair of pericycle cells (LR founder cells) will develop into LRs. In this work, we identified a signaling cascade controlling LR formation through lateral inhibition. It comprises a peptide hormone TARGET OF LBD SIXTEEN 2 (TOLS2), its receptor RLK7, and a downstream transcription factor PUCHI. TOLS2 is expressed at the LR founder cells and inhibits LR initiation. Time-lapse imaging of auxin-responsive DR5:LUCIFERASE reporter expression revealed that occasionally two pairs of LR founder cells are specified in close proximity even in wild-type and that one of them exists only transiently and disappears in an RLK7-dependent manner. We propose that the selection of LR founder cells by the peptide hormone-receptor cascade ensures proper LR spacing.
PMID: 30581155
Plant Cell , IF:9.618 , 2019 Jan , V31 (1) : P52-67 doi: 10.1105/tpc.18.00518
A Robust Auxin Response Network Controls Embryo and Suspensor Development through a Basic Helix Loop Helix Transcriptional Module.
Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708WE Wageningen, the Netherlands.; Plant Biotechnology Institute, National Research Council, 110 Gymnasium Place, Saskatoon, Saskatchewan, Canada S7N 0W9.; Division of Human Nutrition, Wageningen University & Research, Stippeneng 4, 6708WE Wageningen, the Netherlands.; Top Institute Food & Nutrition, Nieuwe Kanaal 9A, 6709 PA Wageningen, the Netherlands.
Land plants reproduce sexually by developing an embryo from a fertilized egg cell. However, embryos can also be formed from other cell types in many plant species. Thus, a key question is how embryo identity in plants is controlled, and how this process is modified during nonzygotic embryogenesis. The Arabidopsis (Arabidopsis thaliana) zygote divides to produce an embryonic lineage and an extra-embryonic suspensor. Yet, normally quiescent suspensor cells can develop a second embryo when the initial embryo is damaged, or when response to the signaling molecule auxin is locally blocked. Here we used auxin-dependent suspensor embryogenesis as a model to determine transcriptome changes during embryonic reprogramming. We found that reprogramming is complex and accompanied by large transcriptomic changes before anatomical changes. This analysis revealed a strong enrichment for genes encoding components of auxin homeostasis and response among misregulated genes. Strikingly, deregulation among multiple auxin-related gene families converged upon the re-establishment of cellular auxin levels or response. This finding points to a remarkable degree of feedback regulation to create resilience in the auxin response during embryo development. Starting from the transcriptome of auxin-deregulated embryos, we identified an auxin-dependent basic Helix Loop Helix transcription factor network that mediates the activity of this hormone in suppressing embryo development from the suspensor.
PMID: 30573473
Plant Cell , IF:9.618 , 2019 Jan , V31 (1) : P250-271 doi: 10.1105/tpc.18.00528
Phosphatidic Acid Directly Regulates PINOID-Dependent Phosphorylation and Activation of the PIN-FORMED2 Auxin Efflux Transporter in Response to Salt Stress.
College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; Laboratory Centre of Life Science, Nanjing Agricultural University, Nanjing 210095, China.; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing 210095, China.; College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China zhangqun@njau.edu.cn.
Remodeling of auxin distribution during the integration of plant growth responses with the environment requires the precise control of auxin influx and efflux transporters. The plasma membrane-localized PIN-FORMED (PIN) proteins facilitate auxin efflux from cells, and their activity is regulated by reversible phosphorylation. How PIN modulates plant cellular responses to external stresses and whether its activity is coordinated by phospholipids remain unclear. Here, we reveal that, in Arabidopsis (Arabidopsis thaliana), the phosphatidic acid (PA)-regulated PINOID (PID) kinase is a crucial modulator of PIN2 activity and auxin redistribution in response to salt stress. Under salt stress, loss of phospholipase D function impaired auxin redistribution and resulted in markedly reduced primary root growth; these effects were reversed by exogenous PA. The phospholipase D-derived PA interacted with PID and increased PID-dependent phosphorylation of PIN2, which activated auxin efflux and altered auxin accumulation, promoting root growth when exposed to salt stress. Ablation of the PA binding motif not only diminished PID accumulation at the plasma membrane but also abolished PA-promoted PID phosphorylation of PIN2 and its function in coping with salt stress; however, this ablation did not affect inflorescence and cotyledon development or PIN2-dependent gravitropic and halotropic responses. Our data indicate a role for PA in coupling extracellular salt signaling to PID-directed PIN2 phosphorylation and polar auxin transport, highlighting the importance of lipid-protein interactions in the spatiotemporal regulation of auxin signaling.
PMID: 30464035
J Hazard Mater , IF:9.038 , 2019 Jan , V362 : P383-393 doi: 10.1016/j.jhazmat.2018.09.029
Oryza sativa class III peroxidase (OsPRX38) overexpression in Arabidopsis thaliana reduces arsenic accumulation due to apoplastic lignification.
CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India; Integral University, Kursi road, Lucknow, Uttar Pradesh, India.; CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India; Academy of Scientific and Innovative Research, New Delhi, India.; CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India.; Integral University, Kursi road, Lucknow, Uttar Pradesh, India.; CSIR-National Botanical Research Institute, Lucknow, Uttar Pradesh, India; Academy of Scientific and Innovative Research, New Delhi, India. Electronic address: debasis1972@rediffmail.com.
ClassIII peroxidases are multigene family of plant-specific peroxidase enzyme. They are involved in various physiological and developmental processes like auxin catabolism, cell metabolism, various biotic, abiotic stresses and cell elongation. In the present study, we identified a class III peroxidase (OsPRX38) from rice which is upregulated several folds in both arsenate (AsV) and arsenite (AsIII) stresses. The overexpression of OsPRX38 in Arabidopsis thaliana significantly enhances Arsenic (As) tolerance by increasing SOD, PRX GST activity and exhibited low H2O2, electrolyte leakage and malondialdehyde content. OsPRX38 overexpression also affect the plant growth by increasing total biomass and seeds production in transgenics than WT under As stress condition. Confocal microscopy revealed that the OsPRX38-YFP fusion protein was localized to the apoplast of the onion epidermal cells. In addition, lignification was positively correlated with an increase in cell-wall-associated peroxidase activities in transgenic plants. This study indicates the role of OsPRX38 in lignin biosynthesis, where lignin act as an apoplastic barrier for As entry in root cells leading to reduction of As accumulation in transgenic. Overall the study suggests that overexpression of OsPRX38 in Arabidopsis thaliana activates the signaling network of different antioxidant systems under As stress condition, enhancing the plant tolerance by reducing As accumulation due to high lignification.
PMID: 30245406
New Phytol , IF:8.512 , 2019 Jan , V221 (2) : P614-617 doi: 10.1111/nph.15539
How to be STYLISH: columbine study sheds new light on the obscure mechanisms of nectary formation.
The Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge, CB2 1LR, UK.
PMID: 30569616
Plant Biotechnol J , IF:8.154 , 2019 Jan , V17 (1) : P289-301 doi: 10.1111/pbi.12977
A CsTu-TS1 regulatory module promotes fruit tubercule formation in cucumber.
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, College of Horticulture, China Agricultural University, Beijing, China.; Beijing Vegetable Research Center (BVRC), Beijing Academy of Agricultural and Forestry Sciences, National Engineering Research Center for Vegetables, Beijing, China.; Tianjin Derit Seeds Co. Ltd, Tianjin, China.
The fruit epidermal features such as the size of tubercules are important fruit quality traits for cucumber production. But the mechanisms underlying tubercule formation remain elusive. Here, tubercule size locus CsTS1 was identified by map-based cloning and was found to encode an oleosin protein. Allelic variation was identified in the promoter region of CsTS1, resulting in low expression of CsTS1 in all 22 different small-warty or nonwarty cucumber lines. High CsTS1 expression levels were closely correlated with increased fruit tubercule size among 44 different cucumber lines. Transgenic complementation and RNAi-mediated gene silencing of CsTS1 in transgenic cucumber plants demonstrated that CsTS1 positively regulates the development of tubercules. CsTS1 is highly expressed in the peel at fruit tubercule forming and enlargement stage. Auxin content and expression of three auxin signalling pathway genes were altered in the 35S:CsTS1 and CsTS1-RNAi fruit tubercules, a result that was supported by comparing the cell size of the control and transgenic fruit tubercules. CsTu, a C2 H2 zinc finger domain transcription factor that regulates tubercule initiation, binds directly to the CsTS1 promoter and promotes its expression. Taken together, our results reveal a novel mechanism in which the CsTu-TS1 complex promotes fruit tubercule formation in cucumber.
PMID: 29905035
Plant Biotechnol J , IF:8.154 , 2019 Jan , V17 (1) : P63-74 doi: 10.1111/pbi.12947
GhL1L1 affects cell fate specification by regulating GhPIN1-mediated auxin distribution.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, Hubei, China.; College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, Hubei, China.
Auxin is as an efficient initiator and regulator of cell fate during somatic embryogenesis (SE), but the molecular mechanisms and regulating networks of this process are not well understood. In this report, we analysed SE process induced by Leafy cotyledon1-like 1 (GhL1L1), a NF-YB subfamily gene specifically expressed in embryonic tissues in cotton. We also identified the target gene of GhL1L1, and its role in auxin distribution and cell fate specification during embryonic development was analysed. Overexpression of GhL1L1 accelerated embryonic cell formation, associated with an increased concentration of IAA in embryogenic calluses (ECs) and in the shoot apical meristem, corresponding to altered expression of the auxin transport gene GhPIN1. By contrast, GhL1L1-deficient explants showed retarded embryonic cell formation, and the concentration of IAA was decreased in GhL1L1-deficient ECs. Disruption of auxin distribution accelerated the specification of embryonic cell fate together with regulation of GhPIN1. Furthermore, we showed that PHOSPHATASE 2AA2 (GhPP2AA2) was activated by GhL1L1 through targeting the G-box of its promoter, hence regulating the activity of GhPIN1 protein. Our results indicate that GhL1L1 functions as a key regulator in auxin distribution to regulate cell fate specification in cotton and contribute to the understanding of the complex process of SE in plant species.
PMID: 29754405
Elife , IF:7.08 , 2019 Jan , V8 doi: 10.7554/eLife.39298
Quantitative analysis of auxin sensing in leaf primordia argues against proposed role in regulating leaf dorsoventrality.
School of Life and Environmental Sciences, University of Sydney, Sydney, Australia.; Sainsbury Laboratory, University of Cambridge, Cambridge, United Kingdom.; Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom.; Department of Astronomy and Theoretical Physics, Lund University, Lund, Sweden.
Dorsoventrality in leaves has been shown to depend on the pre-patterned expression of KANADI and HD-ZIPIII genes within the plant shoot apical meristem (SAM). However, it has also been proposed that asymmetric auxin levels within initiating leaves help establish leaf polarity, based in part on observations of the DII auxin sensor. By analyzing and quantifying the expression of the R2D2 auxin sensor, we find that there is no obvious asymmetry in auxin levels during Arabidopsis leaf development. We further show that the mDII control sensor also exhibits an asymmetry in expression in developing leaf primordia early on, while it becomes more symmetric at a later developmental stage as reported previously. Together with other recent findings, our results argue against the importance of auxin asymmetry in establishing leaf polarity.
PMID: 30667357
PLoS Biol , IF:7.076 , 2019 Jan , V17 (1) : Pe2005258 doi: 10.1371/journal.pbio.2005258
The brown algal mode of tip growth: Keeping stress under control.
CNRS, Sorbonne Universite, Morphogenesis of Macro Algae, UMR8227, Station Biologique, Roscoff, France.; SCRIPPS Institution of Oceanography, University of California, San Diego, San Diego, California, United States of America.; MerImage platform, FR2424, CNRS, Sorbonne Universite, Station Biologique, Roscoff, France.
Tip growth has been studied in pollen tubes, root hairs, and fungal and oomycete hyphae and is the most widely distributed unidirectional growth process on the planet. It ensures spatial colonization, nutrient predation, fertilization, and symbiosis with growth speeds of up to 800 mum h-1. Although turgor-driven growth is intuitively conceivable, a closer examination of the physical processes at work in tip growth raises a paradox: growth occurs where biophysical forces are low, because of the increase in curvature in the tip. All tip-growing cells studied so far rely on the modulation of cell wall extensibility via the polarized excretion of cell wall-loosening compounds at the tip. Here, we used a series of quantitative measurements at the cellular level and a biophysical simulation approach to show that the brown alga Ectocarpus has an original tip-growth mechanism. In this alga, the establishment of a steep gradient in cell wall thickness can compensate for the variation in tip curvature, thereby modulating wall stress within the tip cell. Bootstrap analyses support the robustness of the process, and experiments with fluorescence recovery after photobleaching (FRAP) confirmed the active vesicle trafficking in the shanks of the apical cell, as inferred from the model. In response to auxin, biophysical measurements change in agreement with the model. Although we cannot strictly exclude the involvement of a gradient in mechanical properties in Ectocarpus morphogenesis, the viscoplastic model of cell wall mechanics strongly suggests that brown algae have evolved an alternative strategy of tip growth. This strategy is largely based on the control of cell wall thickness rather than fluctuations in cell wall mechanical properties.
PMID: 30640903
J Adv Res , IF:6.992 , 2019 Jan , V15 : P27-36 doi: 10.1016/j.jare.2018.08.002
Nitric oxide precursors prevent Al-triggered auxin flow inhibition in Triticum aestivum roots.
Departamento de Botanica, Instituto de Ciencias Biologicas, Universidade Federal de Minas Gerais, Av. Pres. Antonio Carlos, 6627, Pampulha, Belo Horizonte, MG 31270-901, Brazil.
Aluminum (Al) is an element widely distributed in soils, even though Al(3+) is one of the most detrimental cations to plant growth. The effect of nitric oxide (NO) precursors on indole-3-acetic acid (IAA) flow towards roots upon Al treatment is herein reported using two Triticum aestivum (wheat) cultivars with recognized differential Al tolerance. Roots of Al-tolerant seedlings with no treatment (control) accumulated higher amounts of NO than Al-sensitive ones. The treatment with Al further stimulated NO production in root cells while root exposure to NO3 (-), L-arginine (Arg) or the NO donor S-nitrosoglutathione (GSNO) decreased both Al and lipid peroxide accumulation in both cultivars. Regardless of the cultivar, NO3 (-), Arg or GSNO prevented the blockage of IAA flow towards roots. Overall, the treatment of wheat roots with NO precursors prior to Al treatment effectively guarantees normal IAA flow towards roots, a condition that favors the organ's growth and development.
PMID: 30581610
Plant Physiol , IF:6.902 , 2019 Jan , V179 (1) : P280-299 doi: 10.1104/pp.18.01041
Auxin Function in the Brown Alga Dictyota dichotoma.
Department of Biology, Ghent University, 9000 Ghent, Belgium kenny.bogaert@ugent.be.; Department of Biology, Ghent University, 9000 Ghent, Belgium.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umea, Sweden.; VIB-UGent Center for Plant Systems Biology, B-9052 Ghent, Belgium.; Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052 Ghent, Belgium.
Auxin controls body plan patterning in land plants and has been proposed to play a similar role in the development of brown algae (Phaeophyta) despite their distant evolutionary relationship with land plants. The mechanism of auxin action in brown algae remains controversial because of contradicting conclusions derived from pharmacological studies on Fucus In this study, we used Dictyota dichotoma as a model system to show that auxin plays a role during the apical-basal patterning of the embryo of brown algae. Indole-3-acetic acid was detectable in D. dichotoma germlings and mature tissue. Although two-celled D. dichotoma zygotes normally develop a rhizoid from one pole and a thallus meristem from the other, addition of exogenous auxins to one-celled embryos affected polarization, and both poles of the spheroidal embryo developed into rhizoids instead. The effect was strongest at lower pH and when variable extrinsic informational cues were applied. 2-[4-(diethylamino)-2-hydroxybenzoyl]benzoic acid, an inhibitor of the ABC-B/multidrug resistance/P-glycoprotein subfamily of transporters in land plants, affected rhizoid formation by increasing rhizoid branching and inducing ectopic rhizoids. An in silico survey of auxin genes suggested that a diverse range of biosynthesis genes and transport genes, such as PIN-LIKES, and the ATP-binding cassette subfamily (ABC-B/multidrug resistance/P-glycoprotein) transporters from land plants have homologs in D. dichotoma and Ectocarpus siliculosus Together with reports on auxin function in basal lineages of green algae, these results suggest that auxin function predates the divergence between the green and brown lineage and the transition toward land plants.
PMID: 30420566
Plant Physiol , IF:6.902 , 2019 Jan , V179 (1) : P55-65 doi: 10.1104/pp.18.00519
Initial Bud Outgrowth Occurs Independent of Auxin Flow from Out of Buds.
School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia.; School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia c.beveridge@uq.edu.au.
Apical dominance is the process whereby the shoot tip inhibits the growth of axillary buds along the stem. It has been proposed that the shoot tip, which is the predominant source of the plant hormone auxin, prevents bud outgrowth by suppressing auxin canalization and export from axillary buds into the main stem. In this theory, auxin flow out of axillary buds is a prerequisite for bud outgrowth, and buds are triggered to grow by an enhanced proportional flow of auxin from the buds. A major challenge of directly testing this model is in being able to create a bud- or stem-specific change in auxin transport. Here we evaluate the relationship between specific changes in auxin efflux from axillary buds and bud outgrowth after shoot tip removal (decapitation) in the pea (Pisum sativum). The auxin transport inhibitor 1-N-naphthylphthalamic acid (NPA) and to a lesser extent, the auxin perception inhibitor p-chlorophenoxyisobutyric acid (PCIB), effectively blocked auxin efflux from axillary buds of intact and decapitated plants without affecting auxin flow in the main stem. Gene expression analyses indicate that NPA and PCIB regulate auxin-inducible, and biosynthesis and transport genes, in axillary buds within 3 h after application. These inhibitors had no effect on initial bud outgrowth after decapitation or cytokinin (benzyladenine; BA) treatment. Inhibitory effects of PCIB and NPA on axillary bud outgrowth only became apparent from 48 h after treatment. These findings demonstrate that the initiation of decapitation- and cytokinin-induced axillary bud outgrowth is independent of auxin canalization and export from the bud.
PMID: 30404820
Plant Cell Environ , IF:6.362 , 2019 Jan , V42 (1) : P337-353 doi: 10.1111/pce.13425
Ectopic expression of a pea apyrase enhances root system architecture and drought survival in Arabidopsis and soybean.
Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas.; Department of Biological Sciences, Goucher College, Towson, Maryland.
Ectoapyrases (ecto-NTPDases) function to decrease levels of extracellular ATP and ADP in animals and plants. Prior studies showed that ectopic expression of a pea ectoapyrase, psNTP9, enhanced growth in Arabidopsis seedlings and that the overexpression of the two Arabidopsis apyrases most closely related to psNTP9 enhanced auxin transport and growth in Arabidopsis. These results predicted that ectopic expression of psNTP9 could promote a more extensive root system architecture (RSA) in Arabidopsis. We confirmed that transgenic Arabidopsis seedlings had longer primary roots, more lateral roots, and more and longer root hairs than wild-type plants. Because RSA influences water uptake, we tested whether the transgenic plants could tolerate osmotic stress and water deprivation better than wild-type plants, and we confirmed these properties. Transcriptomic analyses revealed gene expression changes in the transgenic plants that helped account for their enhanced RSA and improved drought tolerance. The effects of psNTP9 were not restricted to Arabidopsis, because its expression in soybeans improved the RSA, growth, and seed yield of this crop and supported higher survival in response to drought. Our results indicate that in both Arabidopsis and soybeans, the constitutive expression of psNTP9 results in a more extensive RSA and improved survival in drought stress conditions.
PMID: 30132918
J Exp Bot , IF:5.908 , 2019 Jan , V70 (2) : P563-574 doi: 10.1093/jxb/ery384
Reporter gene expression reveals precise auxin synthesis sites during fruit and root development in wild strawberry.
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China.; National Key Laboratory of Crop Genetic Improvement, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.; Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA.
The critical role of auxin in strawberry fruit set and receptacle enlargement was demonstrated previously. While fertilization is known to trigger auxin biosynthesis, the specific tissue source of fertilization-induced auxin is not well understood. Here, the auxin reporter DR5ver2::GUS was introduced into wild strawberry (Fragaria vesca) to reveal auxin distribution in the seed and fruit receptacle pre- and post-fertilization as well as in the root. In addition, the expression of TAR and YUCCA genes coding for enzymes catalysing the two-step auxin biosynthesis pathway was investigated using their respective promoters fused to the beta-glucuronidase (GUS) reporter. Two FveTARs and four FveYUCs were shown to be expressed primarily in the endosperm and embryo inside the achenes as well as in root tips and lateral root primordia. Expression of these reporters in dissected tissues provided more detailed and precise spatial (cell and tissue) and temporal (pre- and post-fertilization) information on where auxin is synthesized and accumulates than previous studies in strawberry. Moreover, we generated CRISPR-mediated knock-out mutants of FveYUC10, the most abundant YUC in seeds; the mutants had a lower free auxin level in young fruit, but displayed no obvious morphological phenotypes. However, overexpression of FveYUC10 resulted in elongated hypocotyls in Arabidopsis caused by elevated auxin level. Overall, the study revealed auxin accumulation in the chalazal seed coat, embryo, receptacle vasculature, root tip, and lateral root primordia and highlighted the endosperm as the main auxin biosynthesis site for fruit set.
PMID: 30371880
J Exp Bot , IF:5.908 , 2019 Jan , V70 (1) : P133-147 doi: 10.1093/jxb/ery334
CBL-interacting protein kinase 25 contributes to root meristem development.
National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India.
Co-ordination of auxin and cytokinin activities determines root meristem size during post-embryonic development. Calcineurin B-like proteins (CBLs) and their interacting protein kinases (CIPKs) constitute signaling modules that relay calcium signals. Here we report that CIPK25 is involved in regulating the root meristem size. Arabidopsis plants lacking CIPK25 expression displayed a short root phenotype and a slower root growth rate with fewer meristem cells. This phenotype was rescued by restoration of CIPK25 expression. CIPK25 interacted with CBL4 and -5, and displayed strong gene expression in the flower and root, except in the cell proliferation domain in the root apical meristem. Its expression in the root was positively and negatively regulated by auxin and cytokinin, respectively. The cipk25 T-DNA insertion line was compromised in auxin transport and auxin-responsive promoter activity. The cipk25 mutant line showed altered expression of auxin efflux carriers (PIN1 and PIN2) and an Aux/IAA family gene SHY2. Decreased PIN1 and PIN2 expression in the cipk25 mutant line was completely restored when combined with a SHY2 loss-of-function mutation, resulting in recovery of root growth. SHY2 and PIN1 expression was partially regulated by cytokinin even in the absence of CIPK25, suggesting a CIPK25-independent cytokinin signaling pathway(s). Our results revealed that CIPK25 plays an important role in the co-ordination of auxin and cytokinin signaling in root meristem development.
PMID: 30239807
J Exp Bot , IF:5.908 , 2019 Jan , V70 (1) : P17-27 doi: 10.1093/jxb/ery332
The SAUR gene family: the plant's toolbox for adaptation of growth and development.
Department of Molecular Plant Physiology, Institute for Water and Wetland Research, Radboud University Nijmegen, Nijmegen, The Netherlands.; Laboratory of Molecular Biology and Business Unit Bioscience, Wageningen University & Research, Wageningen, The Netherlands.
The family of small auxin up-regulated RNA (SAUR) genes is a family of auxin-responsive genes with ~60-140 members in most higher plant species. Despite the early discovery of their auxin responsiveness, their function and mode of action remained unknown for a long time. In recent years, the importance of SAUR genes in the regulation of dynamic and adaptive growth, and the molecular mechanisms by which SAUR proteins act are increasingly well understood. SAURs play a central role in auxin-induced acid growth, but can also act independently of auxin, tissue specifically regulated by various other hormone pathways and transcription factors. In this review, we summarize recent advances in the characterization of the SAUR genes in Arabidopsis and other plant species. We particularly elaborate on their capacity to fine-tune growth in response to internal and external signals, and discuss the breakthroughs in understanding the mode of action of SAURs in relation to their complex regulation.
PMID: 30239806
PLoS Genet , IF:5.174 , 2019 Jan , V15 (1) : Pe1007913 doi: 10.1371/journal.pgen.1007913
Dissecting the pathways coordinating patterning and growth by plant boundary domains.
Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Universite Paris-Saclay, France.; Univ. Paris-Sud, Universite Paris-Saclay, Orsay, France.; Laboratoire de Reproduction et de Developpement des Plantes, INRA, CNRS, ENS de Lyon, UCB Lyon 1, Universite de Lyon, France.
Boundary domains play important roles during morphogenesis in plants and animals, but how they contribute to patterning and growth coordination in plants is not understood. The CUC genes determine the boundary domains in the aerial part of the plants and, in particular, they have a conserved role in regulating leaf complexity across Angiosperms. Here, we used tooth formation at the Arabidopsis leaf margin controlled by the CUC2 transcription factor to untangle intertwined events during boundary-controlled morphogenesis in plants. Combining conditional restoration of CUC2 function with morphometrics as well as quantification of gene expression and hormone signaling, we first established that tooth morphogenesis involves a patterning phase and a growth phase. These phases can be separated, as patterning requires CUC2 while growth can occur independently of CUC2. Next, we show that CUC2 acts as a trigger to promote growth through the activation of three functional relays. In particular, we show that KLUH acts downstream of CUC2 to modulate auxin response and that expressing KLUH can compensate for deficient CUC2 expression during tooth growth. Together, we reveal a genetic and molecular network that allows coordination of patterning and growth by CUC2-defined boundaries during morphogenesis at the leaf margin.
PMID: 30677017
N Biotechnol , IF:4.674 , 2019 Jan , V48 : P76-82 doi: 10.1016/j.nbt.2018.08.001
New hybrid type strigolactone mimics derived from plant growth regulator auxin.
Palacky University, Faculty of Science, Centre of the Region Hana for Biotechnological and Agricultural Research, Department of Chemical Biology and Genetics, Slechtitelu 241/27, CZ-783 71 Olomouc, Czech Republic.; Palacky University, Faculty of Science, Centre of the Region Hana for Biotechnological and Agricultural Research, Department of Chemical Biology and Genetics, Slechtitelu 241/27, CZ-783 71 Olomouc, Czech Republic. Electronic address: tomas.pospisil@upol.cz.; Radboud University, Institute for Molecules and Materials, Cluster of Organic Chemistry, Heyendaalsweg 135, 6525AJ Nijmegen, The Netherlands.; Palacky University, Faculty of Science, Centre of the Region Hana for Biotechnological and Agricultural Research, Department of Chemical Biology and Genetics, Slechtitelu 241/27, CZ-783 71 Olomouc, Czech Republic; Radboud University, Institute for Molecules and Materials, Cluster of Organic Chemistry, Heyendaalsweg 135, 6525AJ Nijmegen, The Netherlands.
Strigolactones (SLs) constitute a new class of plant hormones of increasing importance in plant science. The structure of natural SLs is too complex for ready access by synthesis. Therefore, much attention is being given to design of SL analogues and mimics with a simpler structure but with retention of bioactivity. Here new hybrid type SL mimics have been designed derived from auxins, the common plant growth regulators. Auxins were simply coupled with the butenolide D-ring using bromo (or chloro) butenolide. D-rings having an extra methyl group at the vicinal C-3' carbon atom, or at the C-2' carbon atom, or at both have also been studied. The new hybrid type SL mimics were bioassayed for germination activity of seeds of the parasitic weeds S. hermonthica, O. minor and P. ramosa using the classical method of counting germinated seeds and a colorimetric method. For comparison SL mimics derived from phenyl acetic acid were also investigated. The bioassays revealed that mimics with a normal D-ring had appreciable to good activity, those with an extra methyl group at C-2' were also appreciably active, whereas those with a methyl group in the vicinal C-3' position were inactive (S. hermonthica) or only slightly active. The new hybrid type mimics may be attractive as potential suicidal germination agents in agronomic applications.
PMID: 30077756
N Biotechnol , IF:4.674 , 2019 Jan , V48 : P44-52 doi: 10.1016/j.nbt.2018.06.003
New fluorescently labeled auxins exhibit promising anti-auxin activity.
Laboratory of Growth Regulators, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science of Palacky University & Institute of Experimental Botany of the Czech Academy of Sciences, Slechtitelu 27, CZ-783 71, Olomouc, Czech Republic; Department of Chemical Biology and Genetics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, Slechtitelu 27, CZ-783 71, Olomouc, Czech Republic.; Department of Chemical Biology and Genetics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, Slechtitelu 27, CZ-783 71, Olomouc, Czech Republic.; Department of Biophysics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, Slechtitelu 27, CZ-783 71 Olomouc, Czech Republic.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 83 Umea, Sweden.; Department of Botany, Faculty of Science, Palacky University, Slechtitelu 27, CZ-783 71 Olomouc, Czech Republic.; Laboratory of Growth Regulators, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science of Palacky University & Institute of Experimental Botany of the Czech Academy of Sciences, Slechtitelu 27, CZ-783 71, Olomouc, Czech Republic; Department of Chemical Biology and Genetics, Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University, Slechtitelu 27, CZ-783 71, Olomouc, Czech Republic. Electronic address: asta.zukauskaite@upol.cz.
The plant hormone auxin is a key player in the regulation of plant growth and development. Despite numerous studies devoted to understanding its role in a wide spectrum of physiological processes, full appreciation of its function is linked to a comprehensive determination of its spatio-temporal distribution, which plays a crucial role in its mode of action. Conjugation of fluorescent tracers to plant hormones enables sensitive and specific visualization of their subcellular and tissue-specific localization and transport in planta, which represents a powerful tool for plant physiology. However, to date, only a few fluorescently labeled auxins have been developed. We report the synthesis of four novel fluorescently labeled derivatives of indole-3-acetic acid (IAA) in the form of a conjugate with a nitrobenzoxadiazole (NBD) fluorophore together with validation of their biological activity. These compounds, unlike other previously reported auxins fluorescently labeled at N1 position (nitrogen of the indole ring), do not possess auxin activity but rather show dose-dependent inhibition of auxin-induced effects, such as primary root growth inhibition, root hair growth and the auxin reporter DR5::GUS expression. Moreover, the study demonstrates the importance of the character of the linker and optimal choice of the labeling site in the preparation of fluorescently labeled auxins as important variables influencing their biological activity and fluorescent properties.
PMID: 29953966
Int J Mol Sci , IF:4.556 , 2019 Jan , V20 (3) doi: 10.3390/ijms20030486
Interplay of Auxin and Cytokinin in Lateral Root Development.
Department of Biology, Washington University, St. Louis, MO 63130, USA. hjing@wustl.edu.; Department of Biology, Washington University, St. Louis, MO 63130, USA. strader@wustl.edu.
The spacing and distribution of lateral roots are critical determinants of plant root system architecture. In addition to providing anchorage, lateral roots explore the soil to acquire water and nutrients. Over the past several decades, we have deepened our understanding of the regulatory mechanisms governing lateral root formation and development. In this review, we summarize these recent advances and provide an overview of how auxin and cytokinin coordinate the regulation of lateral root formation and development.
PMID: 30678102
Int J Mol Sci , IF:4.556 , 2019 Jan , V20 (2) doi: 10.3390/ijms20020332
Molecular Mechanisms of Chitosan Interactions with Fungi and Plants.
Department of Marine Sciences and Applied Biology, Laboratory of Plant Pathology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, University of Alicante, 03080 Alicante, Spain. federico.lopez@ua.es.; Department of Marine Sciences and Applied Biology, Laboratory of Plant Pathology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, University of Alicante, 03080 Alicante, Spain. suarezfernandezmarta@gmail.com.; Department of Marine Sciences and Applied Biology, Laboratory of Plant Pathology, Multidisciplinary Institute for Environmental Studies (MIES) Ramon Margalef, University of Alicante, 03080 Alicante, Spain. lv.lopez@ua.es.
Chitosan is a versatile compound with multiple biotechnological applications. This polymer inhibits clinically important human fungal pathogens under the same carbon and nitrogen status as in blood. Chitosan permeabilises their high-fluidity plasma membrane and increases production of intracellular oxygen species (ROS). Conversely, chitosan is compatible with mammalian cell lines as well as with biocontrol fungi (BCF). BCF resistant to chitosan have low-fluidity membranes and high glucan/chitin ratios in their cell walls. Recent studies illustrate molecular and physiological basis of chitosan-root interactions. Chitosan induces auxin accumulation in Arabidopsis roots. This polymer causes overexpression of tryptophan-dependent auxin biosynthesis pathway. It also blocks auxin translocation in roots. Chitosan is a plant defense modulator. Endophytes and fungal pathogens evade plant immunity converting chitin into chitosan. LysM effectors shield chitin and protect fungal cell walls from plant chitinases. These enzymes together with fungal chitin deacetylases, chitosanases and effectors play determinant roles during fungal colonization of plants. This review describes chitosan mode of action (cell and gene targets) in fungi and plants. This knowledge will help to develop chitosan for agrobiotechnological and medical applications.
PMID: 30650540
Int J Mol Sci , IF:4.556 , 2019 Jan , V20 (2) doi: 10.3390/ijms20020235
Expression Analysis of PIN Genes in Root Tips and Nodules of Lotus japonicus.
Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland. izabela_sanko_sawczenko@sggw.pl.; Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland. dominika_dmitruk@sggw.pl.; Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland. barbara_lotocka@sggw.pl.; Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland. elzbieta_rozanska@sggw.pl.; Department of Botany, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Nowoursynowska 159, 02-776 Warsaw, Poland. weronika_czarnocka@sggw.pl.
Auxins are postulated to be one of the pivotal factors in nodulation. However, their transporters in Lotus japonicus, the model species for the study of the development of determinate-type root nodules, have been scarcely described so far, and thus their role in nodulation has remained unknown. Our research is the first focusing on polar auxin transporters in L. japonicus. We analyzed and compared expression of PINs in 20 days post rhizobial inoculation (dpi) and 54 dpi root nodules of L. japonicus by real-time quantitative polymerase chain reaction (qPCR) along with the histochemical beta-glucuronidase (GUS) reporter gene assay in transgenic hairy roots. The results indicate that LjPINs are essential during root nodule development since they are predominantly expressed in the primordia and young, developing nodules. However, along with differentiation, expression levels of several PINs decreased and occurred particularly in the nodule vascular bundles, especially in connection with the root's stele. Moreover, our study demonstrated the importance of both polar auxin transport and auxin intracellular homeostasis during L. japonicus root nodule development and differentiation.
PMID: 30634426
Int J Mol Sci , IF:4.556 , 2019 Jan , V20 (1) doi: 10.3390/ijms20010180
Ontogenetic Changes in Auxin Biosynthesis and Distribution Determine the Organogenic Activity of the Shoot Apical Meristem in pin1 Mutants.
Department of Plant Developmental Biology, Institute of Experimental Biology, Faculty of Biological Sciences, University of Wroclaw, Kanonia 6/8, 50-328 Wroclaw, Poland. alicja.banasiak@uwr.edu.pl.; Department of Plant Developmental Biology, Institute of Experimental Biology, Faculty of Biological Sciences, University of Wroclaw, Kanonia 6/8, 50-328 Wroclaw, Poland. magdalena.biedron@uwr.edu.pl.; Department of Plant Developmental Biology, Institute of Experimental Biology, Faculty of Biological Sciences, University of Wroclaw, Kanonia 6/8, 50-328 Wroclaw, Poland. alicja.dolzblasz@uwr.edu.pl.; Department of Plant Developmental Biology, Institute of Experimental Biology, Faculty of Biological Sciences, University of Wroclaw, Kanonia 6/8, 50-328 Wroclaw, Poland. mateusz.berezowski@uwr.edu.pl.
In the shoot apical meristem (SAM) of Arabidopsis, PIN1-dependent polar auxin transport (PAT) regulates two crucial developmental processes: organogenesis and vascular system formation. However, the knockout mutation in the PIN1 gene does not fully inhibit these two processes. Therefore, we investigated a potential source of auxin for organogenesis and vascularization during inflorescence stem development. We analyzed auxin distribution in wild-type (WT) and pin1 mutant plants using a refined protocol of auxin immunolocalization; auxin activity, with the response reporter pDR5:GFP; and expression of auxin biosynthesis genes YUC1 and YUC4. Our results revealed that regardless of the functionality of PIN1-mediated PAT, auxin is present in the SAM and vascular strands. In WT plants, auxin always accumulates in all cells of the SAM, whereas in pin1 mutants, its localization within the SAM changes ontogenetically and is related to changes in the structure of the vascular system, organogenic activity of SAM, and expression levels of YUC1 and YUC4 genes. Our findings indicate that the presence of auxin in the meristem of pin1 mutants is an outcome of at least two PIN1-independent mechanisms: acropetal auxin transport from differentiated tissues with the use of vascular strands and auxin biosynthesis within the SAM.
PMID: 30621327
ACS Chem Biol , IF:4.434 , 2019 Jan , V14 (1) : P50-57 doi: 10.1021/acschembio.8b00872
Tryptophan Metabolism in Caenorhabditis elegans Links Aggregation Behavior to Nutritional Status.
Department of Chemistry , University of Florida , Gainesville , Florida 32611 , United States.
Caenorhabditis elegans uses aggregation pheromones to communicate its nutritional status and recruit fellow members of its species to food sources. These aggregation pheromones include the IC-ascarosides, ascarosides modified with an indole-3-carbonyl (IC) group on the 4'-position of the ascarylose sugar. Nothing is known about the biosynthesis of the IC modification beyond the fact that it is derived from tryptophan. Here, we show that C. elegans produces endogenously several indole-containing metabolites, including indole-3-pyruvic acid (IPA), indole-3-acetic acid (IAA; auxin), and indole-3-carboxylic acid, and that these metabolites are intermediates in the biosynthetic pathway from tryptophan to the IC group. Stable isotope-labeled IPA and IAA are incorporated into the IC-ascarosides. Importantly, we show that flux through the biosynthetic pathway is affected by the activity of the pyruvate dehydrogenase complex (PDC). Knockdown of the PDC by RNA interference leads to an accumulation of upstream metabolites and a reduction in downstream metabolites in the pathway. Our results show that production of aggregation pheromones is linked to PDC activity and that aggregation behavior may reflect a favorable metabolic state in the worm. Lastly, we show that treatment of C. elegans with indole-containing metabolites in the pathway induces the biosynthesis of the IC-ascarosides. Because the natural environment of C. elegans is rotting plant material, indole-containing metabolites in this environment could potentially stimulate pheromone biosynthesis and aggregation behavior in the worm. Thus, there may be important links between tryptophan metabolism in C. elegans and in plants and bacteria that enable interkingdom signaling.
PMID: 30586284
Aquat Toxicol , IF:4.344 , 2019 Jan , V206 : P154-163 doi: 10.1016/j.aquatox.2018.11.013
Real-time CO2 uptake/emission measurements as a tool for early indication of toxicity in Lemna-tests.
The University of Osijek, Department of Biology, Cara Hadrijana 8A, 31 000 Osijek, Croatia. Electronic address: ersic@biologija.unios.hr.; The University of Osijek, Department of Biology, Cara Hadrijana 8A, 31 000 Osijek, Croatia. Electronic address: tamara.djerdj@biologija.unios.hr.; The University of Osijek, Department of Biology, Cara Hadrijana 8A, 31 000 Osijek, Croatia. Electronic address: martina.varga@biologija.unios.hr.; The University of Osijek, Department of Biology, Cara Hadrijana 8A, 31 000 Osijek, Croatia. Electronic address: hackenberger@biologija.unios.hr.
This paper presents an application of continuous monitoring of the emission and uptake rate of CO2 in Lemna toxicity test. On a real-time basis, the CO2 concentration data were collected by the Arduino platform-based respiratory activity measuring system (ResTox) and reported as CO2 concentration dynamic curves. The results of CO2 measurements demonstrated that tested metals (Co, Cu, Hg, and Cd), as well as herbicides (nicosulfuron, diquat, and tembotrione), stimulated the CO2 exchange rates at low doses, while at high doses CO2 exchange rates were inhibited. The addition of higher concentrations of clopyralid stimulated photosynthetic activity and caused a higher increase in respiration rates indicating its mode of action as auxin mimic herbicide. The results obtained underline the necessity of considering other biological endpoints like continuous measurements of gas exchange from the very beginning of exposure to toxicants. Simultaneous measurements of real-time CO2 concentrations, as the primary effect of toxicant mode of action, and processes that are supported by carbon flux, as the secondary effect or endpoint, are needed to relate actual and substrate-induced or inhibited respiration and photosynthesis to those processes. Therefore, continuous measurements of CO2 exchange rates can be implemented for the initial screening of potential toxicity to give valuable information that is needed for further examination of toxicity mechanisms and risk assessment.
PMID: 30476745
J Agric Food Chem , IF:4.192 , 2019 Jan , V67 (1) : P463-472 doi: 10.1021/acs.jafc.8b04611
Changes in Fruit Firmness, Cell Wall Composition, and Transcriptional Profile in the yellow fruit tomato 1 ( yft1) Mutant.
Fruit firmness is an important trait in tomato ( Solanum lycopersicum), associated with shelf life and economic value; however, the precise mechanism determining fruit softening remains elusive. A yellow fruit tomato 1 ( yft1) mutant harbors a genetic lesion in the YFT1 gene and has significantly firmer fruit than those of the cv. M82 wild type at a red ripe stage, 54 days post-anthesis (dpa). When softening was further dissected, it was found that the yft1 firm fruit phenotype correlated with a difference in cellulose, hemicellulose, and pectin deposition in the primary cell wall (PCW) compared to cv. M82. Alterations in the structure of the pericarp cells, chemical components, hydrolase activities, and expression of genes encoding these hydrolases were all hypothesized to be a result of the loss of YFT1 function. This was further affirmed by RNA-seq analysis, where a total of 183 differentially expressed genes (DEGs, 50/133 down-/upregulated) were identified between yft1 and cv. M82. These DEGs were mainly annotated as participating in ethylene- and auxin-related signal transduction, sugar metabolism, and photosynthesis. This study provides new insights into the mechanism underlying the control of fruit softening.
PMID: 30545217
Physiol Plant , IF:4.148 , 2019 Jan , V165 (1) : P114-122 doi: 10.1111/ppl.12860
Abscisic acid promotes root system development in birch tissue culture: a comparison to aspen culture and conventional rooting-related growth regulators.
Lithuanian Research Centre for Agriculture and Forestry, Institute of Forestry, Liepu str. 1, Girionys, Kaunas, LT-53101, Lithuania.; Department of Biochemistry, Vytautas Magnus University, Vileikos str. 8, Kaunas, LT-44404, Lithuania.
The research aim was to assess the effects of the plant hormone abscisic acid (ABA) and the growth regulator paclobutrazol (PBZ) on root system development during the in vitro culture of different birch and aspen genotypes. The studied genotypes involved two aspen (Populus tremula and Populus tremuloides x P. tremula) and two silver birch (Betula pendula) trees, with one of the birches characterized by its inability to root in vitro. For experiments, apical shoot segments were cultured on nutrient medium enriched with either ABA or PBZ. Additionally, the analysis of the endogenous hormones in shoots developed on hormone-free medium was conducted by high-performance liquid chromatography. The endogenous concentration of auxin indole-3-acetic acid was much higher in the aspens than that in the birches, while the highest concentration of ABA was found in the root-forming birch. The culturing of this birch genotype on medium enriched with ABA resulted in an increased root length and a higher number of lateral roots without any negative effect on either shoot growth or adventitious root (AR) formation, although these two processes were largely inhibited by ABA in the aspens. Meanwhile, PBZ promoted AR formation in both aspen and birch cultures but impaired secondary root formation and shoot growth in birches. These results suggest the use of ABA for the in vitro rooting of birches and PBZ for the rooting of aspens.
PMID: 30367696
Physiol Plant , IF:4.148 , 2019 Jan , V165 (1) : P81-89 doi: 10.1111/ppl.12783
Control of root meristem establishment in conifers.
Umea Plant Science Centre, Department of Plant Physiology, Umea University, Umea, Sweden.; Umea Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umea, Sweden.; Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, Versailles, France.
The evolution of terrestrial plant life was made possible by the establishment of a root system, which enabled plants to migrate from aquatic to terrestrial habitats. During evolution, root organization has gradually progressed from a very simple to a highly hierarchical architecture. Roots are initiated during embryogenesis and branch afterward through lateral root formation. Additionally, adventitious roots can be formed post-embryonically from aerial organs. Induction of adventitious roots (ARs) forms the basis of the vegetative propagation via cuttings in horticulture, agriculture and forestry. This method, together with somatic embryogenesis, is routinely used to clonally multiply conifers. In addition to being utilized as propagation techniques, adventitious rooting and somatic embryogenesis have emerged as versatile models to study cellular and molecular mechanisms of embryo formation and organogenesis of coniferous species. Both formation of the embryonic root and the AR primordia require the establishment of auxin gradients within cells that coordinate the developmental response. These processes also share key elements of the genetic regulatory networks that, e.g. are triggering cell fate. This minireview gives an overview of the molecular control mechanisms associated with root development in conifers, from initiation in the embryo to post-embryonic formation in cuttings.
PMID: 29920700
Physiol Plant , IF:4.148 , 2019 Jan , V165 (1) : P17-28 doi: 10.1111/ppl.12734
A role for ALF4 during gall and giant cell development in the biotic interaction between Arabidopsis and Meloidogyne spp.
Universidad de Castilla-La Mancha, Facultad de Ciencias Ambientales y Bioquimica, Area de Fisiologia Vegetal, Avda, Carlos III, s/n, 45071, Toledo, Spain.
Root-knot nematodes (RKNs; Meloidogyne spp.) are a major pest for the agriculture worldwide. RKNs induce specialized feeding cells (giant cells, GCs) inside galls which are de novo formed pseudo-organs in the roots that share similarities with other developmental processes as lateral root (LR) and callus formation or grafting involving new vascular development or pericycle proliferation. Hence, it is pertinent to study the molecular mechanisms directing the plant-nematode interaction. In this respect, ALF4 is a key gene during LR formation, vascular vessels reconnection in grafting, hormone-induced callus formation or de novo root organogenesis from leaf explants. Our results show that ALF4 is also induced in galls at early infection stages in an auxin-independent way. Furthermore, ALF4 activity is necessary for the formation of proper galls and GCs, as the mutant alf4-1 presents aberrant galls and GCs with severe structural abnormalities leading to a dramatic reduction in the nematode egg production. However, a low-reproduction rate is maintained, that might be explained by the local auxin maximum build by the nematodes in galls, partially rescuing alf4-1 phenotype. This would be similar to the partial rescue described for LR formation with exogenous auxins and also agrees with the LR emergence from alf4-1 galls but not from uninfected roots. In addition, ALF4 is also induced in syncytia formed by cyst nematodes. All these data support a pivotal role for ALF4 during de novo organogenesis processes induced by endoparasitic nematodes, in addition to its role in LR formation, callus development or vessel reconnection during grafting.
PMID: 29573275
Physiol Plant , IF:4.148 , 2019 Jan , V165 (1) : P4-16 doi: 10.1111/ppl.12714
Anatomical and hormonal description of rootlet primordium development along white lupin cluster root.
BPMP, University of Montpellier, CNRS, INRA, SupAgro, Montpellier, France.
Cluster root (CR) is one of the most spectacular plant developmental adaptations to hostile environment. It can be found in a few species from a dozen botanical families, including white lupin (Lupinus albus) in the Fabaceae family. These amazing structures are produced in phosphate-deprived conditions and are made of hundreds of short roots also known as rootlets. White lupin is the only crop bearing CRs and is considered as the model species for CR studies. However, little information is available on CRs atypical development, including the molecular events that trigger their formation. To provide insights on CR formation, we performed an anatomical and cellular description of rootlet development in white lupin. Starting with a classic histological approach, we described rootlet primordium development and defined eight developmental stages from rootlet initiation to their emergence. Due to the major role of hormones in the developmental program of root system, we next focussed on auxin-related mechanisms. We observed the establishment of an auxin maximum through rootlet development in transgenic roots expressing the DR5:GUS auxin reporter. Expression analysis of the main auxin-related genes [TIR, Auxin Response Factor (ARF) and AUX/IAA] during a detailed time course revealed specific expression associated with the formation of the rootlet primordium. We showed that L. albus TRANSPORT INHIBITOR RESPONSE 1b is expressed during rootlet primordium formation and that L. albus AUXIN RESPONSE FACTOR 5 is expressed in the vasculature but absent in the primordium itself. Altogether, our results describe the very early cellular events leading to CR formation and reveal some of the auxin-related mechanisms.
PMID: 29493786
Plant Cell Physiol , IF:4.062 , 2019 Jan , V60 (1) : P38-51 doi: 10.1093/pcp/pcy184
Aberrant Stamen Development is Associated with Parthenocarpic Fruit Set Through Up-Regulation of Gibberellin Biosynthesis in Tomato.
Faculty of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, Japan.; Tsukuba Plant Innovation Research Center, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, Japan.; Graduate School of Environmental and Life and Sciences, Okayama University, Tsushima, Okayama, Japan.; RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama, Japan.; Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan.; Graduate School Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, Japan.
Parthenocarpy, a process in which fruit set occurs without fertilization, leads to the production of seedless fruit. A number of floral homeotic mutants with abnormal stamen development exhibit parthenocarpic fruit set. Flower development is thought to repress ovary growth before anthesis. However, the mechanism of parthenocarpic fruit development caused by aberrant flower formation is poorly understood. To investigate the molecular mechanism of parthenocarpic fruit development in floral homeotic mutants, we performed functional analysis of Tomato APETALA3 (TAP3) by loss-of-function approaches. Organ-specific promoter was used to induce organ-specific loss of function in stamen and ovary/fruit. We observed increased cell expansion in tap3 mutants and TAP3-RNAi lines during parthenocarpic fruit growth. These were predominantly accompanied by the up-regulation of GA biosynthesis genes, including SlGA20ox1, SlGA20ox2, and SlGA20ox3, as well as reduced expression of the GA-inactivating gene SlGA2ox1 and the auxin signaling gene SlARF7 involved in a crosstalk between GA and auxin. These transcriptional profiles are in agreement with the GA levels in these lines. These results suggest that stamen development negatively regulates fruit set by repressing the GA biosynthesis.
PMID: 30192961
Plant Cell Physiol , IF:4.062 , 2019 Jan , V60 (1) : P29-37 doi: 10.1093/pcp/pcy182
Agrobacterium tumefaciens Enhances Biosynthesis of Two Distinct Auxins in the Formation of Crown Galls.
Graduate School of Life Sciences, Tohoku University, Katahira, Aoba-ku, Sendai, Japan.; Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurashiki, Okayama, Japan.; RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, Japan.; Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan.; Section of Cell and Developmental Biology, University of California San Diego, La Jolla, CA, USA.; Department of Biochemistry, Okayama University of Science, Okayama, Japan.; Institute of Global Innovation Research, Tokyo University of Agriculture and Technology, Fuchu, Japan.
The plant pathogen Agrobacterium tumefaciens infects plants and introduces the transferred-DNA (T-DNA) region of the Ti-plasmid into nuclear DNA of host plants to induce the formation of tumors (crown galls). The T-DNA region carries iaaM and iaaH genes for synthesis of the plant hormone auxin, indole-3-acetic acid (IAA). It has been demonstrated that the iaaM gene encodes a tryptophan 2-monooxygenase which catalyzes the conversion of tryptophan to indole-3-acetamide (IAM), and the iaaH gene encodes an amidase for subsequent conversion of IAM to IAA. In this article, we demonstrate that A. tumefaciens enhances the production of both IAA and phenylacetic acid (PAA), another auxin which does not show polar transport characteristics, in the formation of crown galls. Using liquid chromatography-tandem mass spectroscopy, we found that the endogenous levels of phenylacetamide (PAM) and PAA metabolites, as well as IAM and IAA metabolites, are remarkably increased in crown galls formed on the stem of tomato plants, implying that two distinct auxins are simultaneously synthesized via the IaaM-IaaH pathway. Moreover, we found that the induction of the iaaM gene dramatically elevated the levels of PAM, PAA and its metabolites, along with IAM, IAA and its metabolites, in Arabidopsis and barley. From these results, we conclude that A. tumefaciens enhances biosynthesis of two distinct auxins in the formation of crown galls.
PMID: 30169882
Sci Rep , IF:3.998 , 2019 Jan , V9 (1) : P212 doi: 10.1038/s41598-018-36446-5
Dissecting Heterosis During the Ear Inflorescence Development Stage in Maize via a Metabolomics-based Analysis.
National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, 450002, China.; National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, 450002, China. liwh416@163.com.; National Key Laboratory of Wheat and Maize Crop Science, Henan Agricultural University, Zhengzhou, 450002, China. tangjihua1@163.com.; Hubei Collaborative Innovation Center for Grain Industry, Yangtze University, Jingzhou, 434025, China. tangjihua1@163.com.
Heterosis can increase the yield of many crops and has been extensively applied in agriculture. In maize, female inflorescence architecture directly determines grain yield. Thus, exploring the relationship between early maize ear inflorescence development and heterosis regarding yield-related traits may be helpful for characterizing the molecular mechanisms underlying heterotic performance. In this study, we fine mapped the overdominant heterotic locus (hlEW2b), associated with ear width, in an approximately 1.98-Mb region based on analyses of chromosome segment substitution lines and the corresponding testcross population. Maize ear inflorescences at the floral meristem stage were collected from two inbred lines, one chromosome segment substitution line that carried hlEW2b (sub-CSSL16), the receptor parent lx9801, and the Zheng58 x sub-CSSL16 and Zheng58 x lx9801 hybrid lines. A total of 256 metabolites were identified, including 31 and 24 metabolites that were differentially accumulated between the two hybrid lines and between the two inbred lines, respectively. Most of these metabolites are involved in complex regulatory mechanisms important for maize ear development. For example, nucleotides are basic metabolites affecting cell composition and carbohydrate synthesis. Additionally, nicotinate and nicotinamide metabolism is important for photosynthesis, plant stress responses, and cell expansion. Moreover, flavonoid and phenolic metabolites regulate auxin transport and cell apoptosis. Meanwhile, phytohormone biosynthesis and distribution influence the cell cycle and cell proliferation. Our results revealed that changes in metabolite contents may affect the heterotic performance related to ear width and yield in maize hybrid lines. This study provides new clues in heterosis at the metabolomics level and implies that differentially accumulated metabolites made distinct contributions to the heterosis at an early stage of ear inflorescences development.
PMID: 30659214
Microbiol Res , IF:3.97 , 2019 Jan , V218 : P76-86 doi: 10.1016/j.micres.2018.09.008
Isolation and characterization of endophytes from nodules of Mimosa pudica with biotechnological potential.
Centro de Investigacion en Biotecnologia, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos, Mexico.; Centro de Investigacion en Dinamica Celular, IICBA, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos, Mexico.; Division Agroalimentaria, Universidad Tecnologica de la Selva, Ocosingo, Chiapas, Mexico.; Centro de Ciencias Genomicas, Universidad Nacional Autonoma de Mexico, Cuernavaca, Morelos, Mexico.; Division Agroalimentaria, Universidad Tecnologica de la Selva, Ocosingo, Chiapas, Mexico. Electronic address: wova79@hotmail.com.; Centro de Investigacion en Biotecnologia, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos, Mexico. Electronic address: jordi@uaem.mx.
Legumes establish symbiotic relationships with different microorganisms, which could function as plant growth promotion microorganisms (PGPM). The finding of new PGPM strains is important to increase plant production avoiding or diminishing the use of industrial fertilizers. Thus, in this work we evaluated the plant growth promotion traits of ten strains isolated from Mimosa pudica root nodules. According to the 16S rDNA sequence, the microorganisms were identified as Enterobacter sp. and Serratia sp. To the best of our knowledge this is the first report describing and endophytic interaction between Mimosa pudica and Enterobacter sp. These strains have some plant growth promoting traits such as phosphate solubilization, auxin production and cellulase and chitinase activity. Strains identified as Serratia sp. inhibited the growth of the phytopathogenic fungi Fusarium sp., and Alternaria solani and the oomycete Phytophthora capsici. According to their biochemical characteristics, three strains were selected to test their plant growth promoting activity in a medium with an insoluble phosphate source. These bacteria show low specificity for their hosts as endophytes, since they were able to colonize two very different legumes: Phaseolus vulgaris and M. pudica. Seedlings of P. vulgaris were inoculated and grown for fifteen days. Enterobacter sp. NOD1 and NOD10, promoted growth as reflected by an increase in shoot height as well as an increase in the size and emergence of the first two trifolia. We could localize NOD5 as an endophyte in roots in P. vulgaris by transforming the strain with a Green Fluorescent Protein carrying plasmid. Experiments of co-inoculation with different Rhizobium etli strains allowed us to discard that NOD5 can fix nitrogen in the nodules formed by a R. etli Fix(-) strain. The isolates described in this work show biotechnological potential for plant growth promoting activity and production of indoleacetic acid and siderophores.
PMID: 30454661
Rice (N Y) , IF:3.912 , 2019 Jan , V12 (1) : P1 doi: 10.1186/s12284-018-0262-x
Molecular Mechanisms of Root Development in Rice.
State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China.; State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058, China. mcz@zju.edu.cn.
Roots are fundamentally important for growth and development, anchoring the plant to its growth substrate, facilitating water and nutrient uptake from the soil, and sensing and responding to environmental signals such as biotic and abiotic stresses. Understanding the molecular mechanisms controlling root architecture is essential for improving nutrient uptake efficiency and crop yields. In this review, we describe the progress being made in the identification of genes and regulatory pathways involved in the development of root systems in rice (Oryza sativa L.), including crown roots, lateral roots, root hairs, and root length. Genes involved in the adaptation of roots to the environmental nutrient status are reviewed, and strategies for further study and agricultural applications are discussed. The growth and development of rice roots are controlled by both genetic factors and environmental cues. Plant hormones, especially auxin and cytokinin, play important roles in root growth and development. Understanding the molecular mechanisms regulating root architecture and response to environmental signals can contribute to the genetic improvement of crop root systems, enhancing their adaptation to stressful environmental conditions.
PMID: 30631971
BMC Plant Biol , IF:3.497 , 2019 Jan , V19 (1) : P46 doi: 10.1186/s12870-019-1659-4
LBD16 and LBD18 acting downstream of ARF7 and ARF19 are involved in adventitious root formation in Arabidopsis.
Department of Bioenergy Science and Technology, Chonnam National University, Yongbongro 77, Buk-gu, Gwangju, 61186, South Korea.; Department of Bioenergy Science and Technology, Chonnam National University, Yongbongro 77, Buk-gu, Gwangju, 61186, South Korea. jungmkim@jnu.ac.kr.; Kumho Life Science Laboratory, Chonnam National University, Gwangju, 61186, South Korea. jungmkim@jnu.ac.kr.
BACKGROUND: Adventitious root (AR) formation is a complex genetic trait, which is controlled by various endogenous and environmental cues. Auxin is known to play a central role in AR formation; however, the mechanisms underlying this role are not well understood. RESULTS: In this study, we showed that a previously identified auxin signaling module, AUXIN RESPONSE FACTOR(ARF)7/ARF19-LATERAL ORGAN BOUNDARIES DOMAIN(LBD)16/LBD18 via AUXIN1(AUX1)/LIKE-AUXIN3 (LAX3) auxin influx carriers, which plays important roles in lateral root formation, is involved in AR formation in Arabidopsis. In aux1, lax3, arf7, arf19, lbd16 and lbd18 single mutants, we observed reduced numbers of ARs than in the wild type. Double and triple mutants exhibited an additional decrease in AR numbers compared with the corresponding single or double mutants, respectively, and the aux1 lax3 lbd16 lbd18 quadruple mutant was devoid of ARs. Expression of LBD16 or LBD18 under their own promoters in lbd16 or lbd18 mutants rescued the reduced number of ARs to wild-type levels. LBD16 or LBD18 fused to a dominant SRDX repressor suppressed promoter activity of the cell cycle gene, Cyclin-Dependent Kinase(CDK)A1;1, to some extent. Expression of LBD16 or LBD18 was significantly reduced in arf7 and arf19 mutants during AR formation in a light-dependent manner, but not in arf6 and arf8. GUS expression analysis of promoter-GUS reporter transgenic lines revealed overlapping expression patterns for LBD16, LBD18, ARF7, ARF19 and LAX3 in AR primordia. CONCLUSION: These results suggest that the ARF7/ARF19-LBD16/LBD18 transcriptional module via the AUX1/LAX3 auxin influx carriers plays an important role in AR formation in Arabidopsis.
PMID: 30704405
BMC Plant Biol , IF:3.497 , 2019 Jan , V19 (1) : P26 doi: 10.1186/s12870-018-1601-1
Transcriptomic signature reveals mechanism of flower bud distortion in witches'-broom disease of soybean (Glycine max).
Centre for Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute, Library Avenue, PUSA, New Delhi, 110012, India.; Post Graduate Institute, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, 444104, India. jpraveen26@yahoo.co.in.; National Research Centre on Plant Biotechnology, LBS Centre, PUSA Campus, New Delhi, 110012, India.; Post Graduate Institute, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, 444104, India.; Department of Biotechnology, Junagadh Agricultural University, Junagadh, Gujarat, India.; Nuclear Agriculture and Biotechnology Division, Homi Bhabha National Institute, Bhabha Atomic Research Centre (BARC), Trombay, Mumbai, 400 085, India.; ICAR- Directorate of Floricultural Research, College of Agriculture, Pune, Maharashtra, 411 005, India.; Centre for Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute, Library Avenue, PUSA, New Delhi, 110012, India. dinesh.kumar@icar.gov.in.
BACKGROUND: Soybean (Glycine max L. Merril) crop is major source of edible oil and protein for human and animals besides its various industrial uses including biofuels. Phytoplasma induced floral bud distortion syndrome (FBD), also known as witches' broom syndrome (WBS) has been one of the major biotic stresses adversely affecting its productivity. Transcriptomic approach can be used for knowledge discovery of this disease manifestation by morpho-physiological key pathways. RESULTS: We report transcriptomic study using Illumina HiSeq NGS data of FBD in soybean, revealing 17,454 differentially expressed genes, 5561 transcription factors, 139 pathways and 176,029 genic region putative markers single sequence repeats, single nucleotide polymorphism and Insertion Deletion. Roles of PmbA, Zn-dependent protease, SAP family and auxin responsive system are described revealing mechanism of flower bud distortion having abnormalities in pollen, stigma development. Validation of 10 randomly selected genes was done by qPCR. Our findings describe the basic mechanism of FBD disease, right from sensing of phytoplasma infection by host plant triggering molecular signalling leading to mobilization of carbohydrate and protein, phyllody, abnormal pollen development, improved colonization of insect in host plants to spread the disease. Study reveals how phytoplasma hijacks metabolic machinery of soybean manifesting FBD. CONCLUSIONS: This is the first report of transcriptomic signature of FBD or WBS disease of soybean revealing morphological and metabolic changes which attracts insect for spread of disease. All the genic region putative markers may be used as genomic resource for variety improvement and new agro-chemical development for disease control to enhance soybean productivity.
PMID: 30646861
BMC Plant Biol , IF:3.497 , 2019 Jan , V19 (1) : P3 doi: 10.1186/s12870-018-1613-x
Analysis of ambient temperature-responsive transcriptome in shoot apical meristem of heat-tolerant and heat-sensitive broccoli inbred lines during floral head formation.
Department of Life Sciences, National Cheng Kung University, No. 1, University Rd, Tainan City, 701, Taiwan.; Department of Biology, National Changhua University of Education, Changhua, 500, Taiwan.; Kale Biotech. Co, No.218, Fudong St., East Dist, Tainan City, 701, Taiwan.; Department of Life Sciences, National Cheng Kung University, No. 1, University Rd, Tainan City, 701, Taiwan. haojen@mail.ncku.edu.tw.; Institute of Tropical Plant Sciences, National Cheng Kung University, No. 1, University Rd, Tainan City, 701, Taiwan. haojen@mail.ncku.edu.tw.
BACKGROUND: Head formation of broccoli (Brassica oleracea var. italica) is greatly reduced under high temperature (22 degrees C and 27 degrees C). Broccoli inbred lines that are capable of producing heads at high temperatures in summer are varieties that are unique to Taiwan. However, knowledge of the early-activated pathways of broccoli head formation under high temperature is limited. RESULTS: We compared heat-tolerant (HT) and heat-sensitive (HS) transcriptome of broccoli under different temperatures. Weighted gene correlation network analysis (WGCNA) revealed that genes involved in calcium signaling pathways, mitogen-activated protein kinase (MAPK) cascades, leucine-rich repeat receptor-like kinases (LRR-RLKs), and genes coding for heat-shock proteins and reactive oxygen species homeostasis shared a similar expression pattern to BoFLC1, which was highly expressed at high temperature (27 degrees C). Of note, these genes were less expressed in HT than HS broccoli at 22 degrees C. Co-expression analysis identified a model for LRR-RLKs in survival-reproduction tradeoffs by modulating MAPK- versus phytohormones-signaling during head formation. The difference in head-forming ability in response to heat stress between HT and HS broccoli may result from their differential transcriptome profiles of LRR-RLK genes. High temperature induced JA- as well as suppressed auxin- and cytokinin-related pathways may facilitate a balancing act to ensure fitness at 27 degrees C. BoFLC1 was less expressed in HT than HS at 22 degrees C, whereas other FLC homologues were not. Promoter analysis of BoFLC1 showed fewer AT dinucleotide repeats in HT broccoli. These results provide insight into the early activation of stress- or development-related pathways during head formation in broccoli. The identification of the BoFLC1 DNA biomarker may facilitate breeding of HT broccoli. CONCLUSIONS: In this study, HT and HS broccoli genotypes were used to determine the effect of temperature on head formation by transcriptome profiling. On the basis of the expression pattern of high temperature-associated signaling genes, the HS transcriptome may be involved in stress defense instead of transition to the reproductive phase in response to heat stress. Transcriptome profiling of HT and HS broccoli helps in understanding the molecular mechanisms underlying head-forming capacity and in promoting functional marker-assisted breeding.
PMID: 30606114
Molecules , IF:3.267 , 2019 Jan , V24 (3) doi: 10.3390/molecules24030451
Metabolism and Biological Activities of 4-Methyl-Sterols.
CVACBA, Instituto de Ciencias Biologicas, Universidade Federal do Para, Belem, PA 66075-750, Brazil. sylvain@ufpa.br.; Plant Isoprenoid Biology (PIB) team, Institut de Biologie Moleculaire des Plantes du CNRS, Universite de Strasbourg, Strasbourg 67084, France. hubert.schaller@ibmp-cnrs.unistra.fr.
4,4-Dimethylsterols and 4-methylsterols are sterol biosynthetic intermediates (C4-SBIs) acting as precursors of cholesterol, ergosterol, and phytosterols. Their accumulation caused by genetic lesions or biochemical inhibition causes severe cellular and developmental phenotypes in all organisms. Functional evidence supports their role as meiosis activators or as signaling molecules in mammals or plants. Oxygenated C4-SBIs like 4-carboxysterols act in major biological processes like auxin signaling in plants and immune system development in mammals. It is the purpose of this article to point out important milestones and significant advances in the understanding of the biogenesis and biological activities of C4-SBIs.
PMID: 30691248
Yeast , IF:3.143 , 2019 Jan , V36 (1) : P75-81 doi: 10.1002/yea.3362
A fast and tuneable auxin-inducible degron for depletion of target proteins in budding yeast.
Wellcome Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
The auxin-inducible degron (AID) is a useful technique to rapidly deplete proteins of interest in nonplant eukaryotes. Depletion is achieved by addition of the plant hormone auxin to the cell culture, which allows the auxin-binding receptor, TIR1, to target the AID-tagged protein for degradation by the proteasome. Fast depletion of the target protein requires good expression of TIR1 protein, but as we show here, high levels of TIR1 may cause uncontrolled depletion of the target protein in the absence of auxin. To enable conditional expression of TIR1 to a high level when required, we regulated the expression of TIR1 using the beta-estradiol expression system. This is a fast-acting gene induction system that does not cause secondary effects on yeast cell metabolism. We demonstrate that combining the AID and beta-estradiol systems results in a tightly controlled and fast auxin-induced depletion of nuclear target proteins. Moreover, we show that depletion rate can be tuned by modulating the duration of beta-estradiol preincubation. We conclude that TIR1 protein is a rate-limiting factor for target protein depletion in yeast, and we provide new tools that allow tightly controlled, tuneable, and efficient depletion of essential proteins whereas minimising secondary effects.
PMID: 30375036
Funct Integr Genomics , IF:3.058 , 2019 Jan , V19 (1) : P29-41 doi: 10.1007/s10142-018-0625-9
Structural and functional evolution of an auxin efflux carrier PIN1 and its functional characterization in common wheat.
Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, Punjab, India.; Department of Crop and Soil Sciences, Washington State University, Pullman, WA, USA.; School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, Punjab, India.; Gene Shifters, LLC, Pullman, WA, USA.; Department of Crop and Soil Sciences, Washington State University, Pullman, WA, USA. ksgill@wsu.edu.
Particularly PIN1, PIN protein-mediated rate-limiting auxin distribution plays a critical role in plant differentiation. Although well-characterized in Arabidopsis, little is known about the structural and functional relationship of the PIN1 gene among other plants. Here, we report that the gene structure remained conserved among bryophytes and angiosperms while the gene size varied by ~ 17%. Although the positions were conserved, highly variable intron phase suggests preference for specific regions in the gene sequence for independent events of intron insertion. Significant variation was observed across gene length for insertions and deletions that were mainly localized to the exonic regions flanking intron 1, possibly demarcating the sequences prone to deletions/duplications. The N and C-terminals showed a higher protein sequence similarity (~ 80%) compared to the central hydrophilic loop (~ 26%). In addition to the signature domains and motifs, we identified four novel uncharacterized motifs in the central divergent loop of PIN1 protein. Three different homo-loci, one each on chromosome groups 4, 6, and 7, were identified in wheat each showing dramatically different expression patterns during different plant developmental stages. Virus-induced gene silencing of the TaPIN1 gene resulted up to 26% reduction in plant height. Because of its direct role in controlling plant height along with a higher expression during stem elongation, the TaPIN1 gene can be manipulated to regulate plant height.
PMID: 29968001
FEBS Lett , IF:3.057 , 2019 Jan , V593 (1) : P97-106 doi: 10.1002/1873-3468.13292
FERONIA regulates auxin-mediated lateral root development and primary root gravitropism.
State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, China.; Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China.
The Arabidopsis FERONIA (FER) receptor kinase is a key hub of cell signaling networks mediating various hormone, stress, and immune responses. Previous studies have shown that FER functions correlate with auxin responses, but the underlying molecular mechanism is unknown. Here, we demonstrate that the primary root of the fer-4 mutant displays increased lateral root branching and a delayed gravitropic response, which are associated with polar auxin transport (PAT). Our data suggest that aberrant PIN2 polarity is responsible for the delayed gravitropic response in fer-4. Furthermore, the diminished F-actin cytoskeleton in fer-4 implies that FER modulates F-actin-mediated PIN2 polar localization. Our findings provide new insights into the function of FER in PAT.
PMID: 30417333
Pathogens , IF:3.018 , 2019 Jan , V8 (1) doi: 10.3390/pathogens8010006
The Effect of Bacillus licheniformis MH48 on Control of Foliar Fungal Diseases and Growth Promotion of Camellia oleifera Seedlings in the Coastal Reclaimed Land of Korea.
Division of Forest Resources, Chonnam National University, Gwangju 61186, Korea. lazyno@naver.com.; Division of Forest Resources, Chonnam National University, Gwangju 61186, Korea. wg6102@naver.com.; Department of Fire Safety Engineering, Jeonju University, Jeollabuk-do 55069, Korea. 72donghyunkim@jj.ac.kr.; Division of Forest Resources, Chonnam National University, Gwangju 61186, Korea. ysahn@jnu.ac.kr.
This study investigated the control of foliar fungal diseases and growth promotion of Camellia oleifera seedlings in coastal reclaimed land through the use of Bacillus licheniformis MH48. B. licheniformis MH48 can produce lytic enzymes chitinase and beta-1,3-glucanase that can inhibit foliar pathogens by 37.4 to 50.5%. Nevertheless, foliar diseases appeared in the seedlings with bacterial inoculation, and their survival rate decreased because they were unable to withstand salt stress. However, B. licheniformis MH48 significantly increased the total nitrogen and phosphorus contents in the soils through fixing atmospheric nitrogen and solubilizing phosphorus. The growth of seedlings with bacterial inoculation increased, particularly in root dry weight, by 7.42 g plant(-1), which was 1.7-fold greater than that of the control. B. licheniformis MH48 produces the phytohormone auxin, which potentially stimulates seedling root growth. C. oleifera seedlings significantly increased in total nitrogen content to 317.57 mg plant(-1) and total phosphorus content to 46.86 mg plant(-1). Our results revealed the effectiveness of B. licheniformis MH48 not only in the control of foliar fungal diseases but also in the growth promotion of C. oleifera seedlings in coastal lands.
PMID: 30634390
J Plant Physiol , IF:3.013 , 2019 Jan , V232 : P257-269 doi: 10.1016/j.jplph.2018.11.004
Expression profiles of organogenesis-related genes over the time course of one-step de novo shoot organogenesis from intact seedlings of kohlrabi.
Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia. Electronic address: tatjana@ibiss.bg.ac.rs.; Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Bulevar despota Stefana 142, 11060 Belgrade, Serbia.
Kohlrabi (Brassica oleracea var. gongylodes) is an important vegetable crop that is able to undergo shoot regeneration in culture from intact seedlings in a single-step regeneration process, using cytokinin as the only plant growth regulator. In this work, we present the expression profiles of seven organogenesis-related genes over the time course of shoot regeneration from intact seedlings of kohlrabi cv. Vienna Purple on shoot regeneration media containing trans-zeatin, cis-zeatin, benzyl adenine or thidiazuron. Two auxin transporter genes - PIN3 and PIN4, a cytokinin response regulator - ARR5, two shoot apical meristem-related transcription factors - CUC1 and RGD3, and two cell cycle-related genes - CDKB2;1 and CYCB2;4 - displayed bimodal expression patterns on most cytokinin-containing media when their expression levels were normalized against control plants grown on hormone-free media. The first expression peak corresponded to direct upregulation by cytokinin from the growth media, and the second one reflected transcriptional events related to callus formation and/or acquisition of organogenic competence, corresponding to the shoot regeneration phases that have already been characterized in Arabidopsis thaliana. We demonstrate that the genes involved in the two-step shoot regeneration of Arabidopsis display their expected expression profiles during the single-step shoot regeneration of its close phylogenetic relative kohlrabi confirming the universality of their roles in the distinct phases of the regeneration process in Brassicaceae. The results presented here represent a first step towards genetic characterization of the morphogenetic processes in this important crop species.
PMID: 30537612
J Plant Physiol , IF:3.013 , 2019 Jan , V232 : P39-50 doi: 10.1016/j.jplph.2018.11.006
Rice BIG gene is required for seedling viability.
State Key Laboratory of Hybrid Rice, Department of Plant Science, College of Life Sciences, Wuhan University, Wuhan, 430072, China.; State Key Laboratory of Hybrid Rice, Department of Plant Science, College of Life Sciences, Wuhan University, Wuhan, 430072, China. Electronic address: ykliang@whu.edu.cn.
Arabidopsis BIG (AtBIG) gene encodes an enormous protein that is required for auxin transport. Loss of AtBIG function not only profoundly changes plant architecture but also alters plant adaptability to environmental stimuli. A putative homolog of AtBIG exists in the rice genome, but no function has been ascribed to it. In this study, we focus on the characterization of the gene structure and function of OsBIG. Sequence and phylogenetic analysis shows that the homologs of OsBIG have high amino acid conservation in several domains across species. Transgenic rice plants in which the expression of OsBIG was disrupted through the CRISPR/Cas9 system-mediated genome editing were used for phenotypic analysis. The Osbig/- plants show high levels of cell death, enhanced electrolyte leakage and membrane lipid peroxidation, and reduced chlorophyll content, which likely accounted for the seedling lethality. Moreover, gene expression between Osbig/- and wild-type plants analyzed by RNA-seq indicates that a number of metabolic and hormonal pathways including ribosome, DNA replication, photosynthesis, and chlorophyll metabolism were significantly perturbed by OsBIG deficiency. In summary, OsBIG gene is integral to the normal growth and development in rice.
PMID: 30530202
Biochem Biophys Res Commun , IF:2.985 , 2019 Jan , V508 (3) : P695-700 doi: 10.1016/j.bbrc.2018.11.082
Histone deacetylases HDA6 and HDA9 coordinately regulate valve cell elongation through affecting auxin signaling in Arabidopsis.
State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resource, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China.; Institute of Plant Biology, College of Life Science, National Taiwan University, Taipei, 106, Taiwan.; State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resource, School of Life Sciences, Sun Yat-Sen University, Guangzhou, China. Electronic address: huangsz@mail.sysu.edu.cn.
Both Histone Deacetylases HDA6 and HDA9 belong to class I subfamily of RPD3/HDA1 HDACs. Loss-of-function mutants of HDA9 form slightly blunt siliques. However, the involvement of HDA6 in regulating silique tip growth is unclear. In this study, we show that HDA6 acts redundantly with HDA9 in regulating the elongation of valve cells in the silique tip. Although the hda6 single mutant does not exhibit a detectable silique phenotype, the silique tip of hda6 hda9 double mutant displays a more severe bulge, a morphology we termed as "nock-shaped". The valve cells of the silique tip of hda9 are longer than wild-type, and loss of HDA6 in hda9 enhances the valve cell elongation phenotype. The transcript levels of auxin-signaling-related genes are mis-regulated in hda9 and hda6 hda9 siliques, and the GFP reporter driven by the auxin response promoter DR5 is weaker in hda9 or hda6 hda9 than wild-type or hda6. Thus, our findings reveal that HDA6 and HDA9 coordinately control the elongation of silique valve cells through regulating the expression of auxin-related genes in silique tips.
PMID: 30527808
Gene , IF:2.984 , 2019 Jan , V682 : P67-80 doi: 10.1016/j.gene.2018.10.008
Target-mimicry based diminution of miRNA167 reinforced flowering-time phenotypes in tobacco via spatial-transcriptional biases of flowering-associated miRNAs.
School of Biotechnology, Gautam Buddha University, Greater Noida 201310 U.P., India.; School of Biotechnology, Gautam Buddha University, Greater Noida 201310 U.P., India. Electronic address: bhupendrach@gmail.com.
Evolutionarily conserved microRNAs such as miR156, miR159, miR167 and miR172 tightly regulate the extensive array of gene expression during flowering in plants, through instant and long-term alterations in the expression of their target genes. Here we employed a novel target-mimicry approach for the diminution of auxin signalling regulator miRNA167 by developing mimic-transgenic lines in tobacco, to investigate the transcriptional biases of flowering-associated miRNAs in apical and floral meristematic tissues and their phenotypic implications. Recorded morpho-alterations such as uneven flowering-time phenotypes, anomalous floral organ formation, and large variations in the seed forming characteristics permitted us to determine the consequence of the extent of miR167 expression diminution accompanying the transcriptional biases of interrelated miRNAs. We demonstrate that percent diminution of miR167 gene expression is proportionally associated with both early and late flowering-time phenotypes in mimic lines. Also, the associated miRNAs, miR156, miR159, and miR172 showed >90% transcriptional diminution in at least 'early-flowering' miR167 mimic lines. On contrary, low percentages of their respective diminution were recorded in 'late-flowering' lines. Evidently, the misexpression of miR156, miR159, and miR172 led to the over-expression of their respective target genes SPL9, AtMYB33-like and AP2 genes in mimic lines which resulted in assorted phenotypes. We describe the scope of spatial regulation of these microRNAs in floral bud tissues of mimic lines which showed negative- or very low (<25%) misexpression levels in early/late-flowering lines highlighting their roles in the acquisition of flowering mechanism. To our knowledge, this study represents the first characterization of transcriptional biases of flowering associated miRNAs in miR167-mimic lines and certainly augments our understanding of the importance of microRNA-mediated regulation of flowering in plants.
PMID: 30292869
Gene , IF:2.984 , 2019 Jan , V680 : P84-96 doi: 10.1016/j.gene.2018.09.033
Transcriptome profiling and identification of the functional genes involved in berry development and ripening in Vitis vinifera.
Shandong Key Laboratory of Plant Biotechnology, College of Life Sciences, Qingdao Agricultural University, Qingdao 266109, People's Republic of China. Electronic address: maqian51856@qau.edu.cn.; Shandong Key Laboratory of Plant Biotechnology, College of Life Sciences, Qingdao Agricultural University, Qingdao 266109, People's Republic of China.
The length of berry lag phase determines the overall time needed for grape berries to get mature, but the functional gene networks in this phase have not been well documented. In order to reveal the origin of the somatic variation and regulation mechanism of grape berry development and ripening, an early ripening mutant of Vitis vinifera with a shorter lag phase was used for transcriptome profiling. The RNA-seq results revealed that 2021 and 2470 genes were up- and down-regulated, respectively, in the early ripening mutant compared to the wild type. The GO and KEGG enrichment analysis indicated that the up-regulated genes belonged to several pathways and metabolisms, among which the most significant constituents were for biosynthesis of secondary metabolites and flavonoid biosynthesis. The down-regulated genes were involved in biosynthesis of secondary metabolites, plant hormone signal transduction, and photosynthesis. Many transcription factors including WRKYs, AP2-EREBPs, and MYBs were also differentially expressed, suggesting their regulatory roles in berry development and ripening. The transcriptomic comparisons suggested that the prominent up-regulation of an Arabidopsis SnRK3.23, CIPK23 or PKS17 homolog could have driven the early ripening phenotype in the mutant by activating the downstream VvABF2 transcription factor in the ABA signaling. At the same time, ethylene and auxin were also involved in this process. As a result, the major ripening related genes, e.g., MYBA1, MYBA2, VvUFGT, GRIP22, and STS were activated in the mutant. The results are of importance for future studies on manipulation of grape berry ripening time.
PMID: 30257181
Saudi J Biol Sci , IF:2.802 , 2019 Jan , V26 (1) : P66-73 doi: 10.1016/j.sjbs.2016.12.023
An estimation of the effects of synthetic auxin and cytokinin and the time of their application on some morphological and physiological characteristics of Medicago x varia T. Martyn.
Department of Grassland and Green Areas Creation, Institute of Agronomy, Siedlce University of Natural Sciences and Humanities, 14 B. Prusa Street, 08-110 Siedlce, Poland.
The aim of the experiment was to determine the effects of synthetic auxin and cytokinin and the time of their application on some morphological and physiological characteristics of Medicago x varia T. Martyn grown under controlled conditions. The experiment was to check whether an application of exogenous hormones during vegetative and generative stages of the plant had an effect on above-ground mass development, on nitrate reductase activity and on plastid pigments content. Experiment factor was synthetic auxin and cytokinin and the date of their application. Auxin was applied in the form of a synthetic indole-3-butyric acid, while cytokinin was sprayed as synthetic 6-benzylaminopurine. The control plants were treated with distilled water. Depending on the experimental variant, spraying was applied at the sixth true leaf stage and at the first flower bud stage. The research showed that the response of the alfalfa plants to the application of cytokinin and auxin was not uniform. It seems that the most effective was the application of a mixture of them both but only during the vegetative stage. Additionally, cytokinin caused an increase in plastid pigments content in alfalfa leaves. On the other hand, a mixture of auxin and cytokinin triggered the highest nitrate reductase activity in alfalfa roots and raised the ratio of total chlorophyll content to carotenoids. Synthetic auxin caused the decrease of the levels of most parameters compared to the control.
PMID: 30622408
Saudi J Biol Sci , IF:2.802 , 2019 Jan , V26 (1) : P38-48 doi: 10.1016/j.sjbs.2016.11.015
Comparing symbiotic performance and physiological responses of two soybean cultivars to arbuscular mycorrhizal fungi under salt stress.
Botany and Microbiology Department, Faculty of Science, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia.; Mycology and Plant Disease Survey Department, Plant Pathology Research Institute, Agriculture Research Center, Giza 12511, Egypt.; Plant Production Department, Faculty of Food & Agricultural Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia.; Seed Pathology Department, Plant Pathology Research Institute, Agriculture Research Center, Giza 12511, Egypt.; Institute of Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF), 15374 Muncheberg, Germany.
The presented experiments evaluated the symbiotic performance of soybean genotypes with contrasting salt stress tolerance to arbuscular mycorrhizal fungi (AMF) inoculation. In addition, the physiological stress tolerance mechanisms in plants derived from mutualistic interactions between AMF and the host plants were evaluated. Plant growth, nodulation, nitrogenase activity and levels of endogenous growth hormones, such as indole acetic acid and indole butyric acid, of salt-tolerant and salt-sensitive soybean genotypes significantly decreased at 200 mM NaCl. The inoculation of soybean with AMF improved the symbiotic performance of both soybean genotypes by improving nodule formation, leghemoglobin content, nitrogenase activity and auxin synthesis. AMF colonization also protected soybean genotypes from salt-induced membrane damage and reduced the production of hydrogen peroxide, subsequently reducing the production of TBARS and reducing lipid peroxidation. In conclusion, the results of the present investigation indicate that AMF improve the symbiotic performance of soybean genotypes regardless of their salt stress tolerance ability by mitigating the negative effect of salt stress and stimulating endogenous level of auxins that contribute to an improved root system and nutrient acquisition under salt stress.
PMID: 30622405
Plants (Basel) , IF:2.762 , 2019 Jan , V8 (2) doi: 10.3390/plants8020030
Evolutionary Analysis of GH3 Genes in Six Oryza Species/Subspecies and Their Expression under Salinity Stress in Oryza sativa ssp. japonica.
State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. Weilong.Kong@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. zhonghua0103@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. 2017102040003@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. mayankgautam@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. Gziyun@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. Yue.Zhang-@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. zhaogangqing@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. lchang@whu.edu.cn.; State Key Laboratory for Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan 430072, China. lysh2001@whu.edu.cn.
Glycoside Hydrolase 3 (GH3), a member of the Auxin-responsive gene family, is involved in plant growth, the plant developmental process, and various stress responses. The GH3 gene family has been well-studied in Arabidopsis thaliana and Zea mays. However, the evolution of the GH3 gene family in Oryza species remains unknown and the function of the GH3 gene family in Oryza sativa is not well-documented. Here, a systematic analysis was performed in six Oryza species/subspecies, including four wild rice species and two cultivated rice subspecies. A total of 13, 13, 13, 13, 12, and 12 members were identified in O. sativa ssp. japonica, O. sativa ssp. indica, Oryza rufipogon, Oryza nivara, Oryza punctata, and Oryza glumaepatula, respectively. Gene duplication events, structural features, conserved motifs, a phylogenetic analysis, chromosome locations, and Ka/Ks ratios of this important family were found to be strictly conservative across these six Oryza species/subspecies, suggesting that the expansion of the GH3 gene family in Oryza species might be attributed to duplication events, and this expansion could occur in the common ancestor of Oryza species, even in common ancestor of rice tribe (Oryzeae) (23.07~31.01 Mya). The RNA-seq results of different tissues displayed that OsGH3 genes had significantly different expression profiles. Remarkably, the qRT-PCR result after NaCl treatment indicated that the majority of OsGH3 genes play important roles in salinity stress, especially OsGH3-2 and OsGH3-8. This study provides important insights into the evolution of the GH3 gene family in Oryza species and will assist with further investigation of OsGH3 genes' functions under salinity stress.
PMID: 30682815
Physiol Mol Biol Plants , IF:2.005 , 2019 Jan , V25 (1) : P13-29 doi: 10.1007/s12298-018-0588-2
Gene expression analysis of bud burst process in European hazelnut (Corylus avellana L.) using RNA-Seq.
1Department of Agricultural Biotechnology, Faculty of Agriculture, Ondokuz Mayis University, Samsun, Turkey.0000 0004 0574 2310grid.411049.9; 2Giresun Hazelnut Research Station, Ministry of Food, Agriculture and Livestock, Giresun, Turkey.0000 0004 0514 8119grid.425815.f
The control of bud burst process depending on temperature is crucial factor in woody perennial plants to survive in unfavorable ecological conditions. Although it has important economic and agronomic values, little information is available on the molecular mechanism of the bud burst process in Corylus avellana. Here for the first time, we conducted a de novo transcriptome-based experiment using eco-dormant leaf bud tissues. Four transcriptome libraries were constructed from the leaf bud tissues and sequenced via Illumina platform. Transcriptome analysis revealed 86,394 unigenes with a mean length of 1189 nt and an N50 of 1916 nt. Among these unigenes, 63,854 (73.78%) of them were annotated by at least one database. De novo assembled transcripts were enriched in phenylpropanoid metabolism, phytohormone biosynthesis and signal transduction pathways. Analyses of phytohormone-associated genes revealed important changes during bud burst, in response to gibberellic acid, auxin, and brassinosteroids. Approximately 2163 putative transcription factors were predicted, of which the largest number of unique transcripts belonged to the MYB transcription factor family. These results contribute to a better understanding of the regulation of bud burst genes in perennial plants.
PMID: 30804627
Biosci Biotechnol Biochem , IF:1.516 , 2019 Jan , V83 (1) : P129-136 doi: 10.1080/09168451.2018.1525275
Identification of an aldehyde oxidase involved in indole-3-acetic acid synthesis in Bombyx mori silk gland.
a Department of Food and Life Sciences , Ibaraki University , Inashiki , Japan.; b United Graduate School of Agricultural Science , Tokyo University of Agriculture and Technology , Fuchu-shi , Japan.
Auxin is thought to be an important factor in the induction of galls by galling insects. We have previously shown that both galling and nongalling insects synthesize indole-3-acetic acid (IAA) from tryptophan (Trp) via two intermediates, indole-3-acetaldoxime (IAOx) and indole-3-acetaldehyde (IAAld). In this study, we isolated an enzyme that catalyzes the last step "IAAld --> IAA" from a silk-gland extract of Bombyx mori. The enzyme, designated "BmIAO1", contains two 2Fe-2S iron-sulfur-cluster-binding domains, an FAD-binding domain, and a molybdopterin-binding domain, which are conserved in aldehyde oxidases. BmIAO1 causes the nonenzymatic conversion of Trp to IAAld and the enzymatic conversion of IAOx to IAA, suggesting that BmIAO1 alone is responsible for IAA production in B. mori. However, a detailed comparison of pure BmIAO1 and the crude silk-gland extract suggested the presence of other enzymes involved in IAA production from Trp. Abbreviations: BA: benzoic acid; CE: collision energy; CXP: collision cell exit potential; DP: declustering potential; IAA: indole-3-acetic acid; IBI1: IAA biosynthetic inhibitor-1; IAAld: indole-3-acetaldehyde; ICA: indole-3-carboxylic acid; IAOx: indole-3-acetaldoxime; IEtOH: indole-3-ethanol; LC-MS/MS: liquid chromatography-tandem mass spectrometry; Trp: tryptophan.
PMID: 30286706