Nature , IF:42.778 , 2021 Apr , V592 (7856) : P768-772 doi: 10.1038/s41586-021-03425-2
A biosensor for the direct visualization of auxin.
Max Planck Institute for Developmental Biology, Tubingen, Germany.; Institute for Biological and Medical Imaging, Helmholtz Zentrum Munich, German Research Center for Environmental Health, Munich, Germany.; Department of Biochemistry, University of Bayreuth, Bayreuth, Germany.; Centre for Plant Molecular Biology, University of Tubingen, Tubingen, Germany.; Max Planck Institute for Developmental Biology, Tubingen, Germany. birte.hoecker@uni-bayreuth.de.; Department of Biochemistry, University of Bayreuth, Bayreuth, Germany. birte.hoecker@uni-bayreuth.de.; Max Planck Institute for Developmental Biology, Tubingen, Germany. gerd.juergens@tuebingen.mpg.de.
One of the most important regulatory small molecules in plants is indole-3-acetic acid, also known as auxin. Its dynamic redistribution has an essential role in almost every aspect of plant life, ranging from cell shape and division to organogenesis and responses to light and gravity(1,2). So far, it has not been possible to directly determine the spatial and temporal distribution of auxin at a cellular resolution. Instead it is inferred from the visualization of irreversible processes that involve the endogenous auxin-response machinery(3-7); however, such a system cannot detect transient changes. Here we report a genetically encoded biosensor for the quantitative in vivo visualization of auxin distribution. The sensor is based on the Escherichia coli tryptophan repressor(8), the binding pocket of which is engineered to be specific to auxin. Coupling of the auxin-binding moiety with selected fluorescent proteins enables the use of a fluorescence resonance energy transfer signal as a readout. Unlike previous systems, this sensor enables direct monitoring of the rapid uptake and clearance of auxin by individual cells and within cell compartments in planta. By responding to the graded spatial distribution along the root axis and its perturbation by transport inhibitors-as well as the rapid and reversible redistribution of endogenous auxin in response to changes in gravity vectors-our sensor enables real-time monitoring of auxin concentrations at a (sub)cellular resolution and their spatial and temporal changes during the lifespan of a plant.
PMID: 33828298
J Pineal Res , IF:14.528 , 2021 May , V70 (4) : Pe12736 doi: 10.1111/jpi.12736
Melatonin inhibits seed germination by crosstalk with abscisic acid, gibberellin, and auxin in Arabidopsis.
State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China.; Biocontrol Engineering Research Center of Plant Disease and Pest, Biocontrol Engineering Research Center of Crop Disease and Pest, School of Ecology and Environmental Science, Yunnan University, Kunming, China.; Department of Cell Systems and Anatomy, UT Health San Antonio, Long School of Medicine, San Antonio, TX, USA.
Seed germination, an important developmental stage in the life cycle of seed plants, is regulated by complex signals. Melatonin is a signaling molecule associated with seed germination under stressful conditions, although the underlying regulatory mechanisms are largely unknown. In this study, we showed that a low concentration (10 microM or 100 microM) of melatonin had no effect on seed germination, but when the concentration of melatonin increased to 500 microM or 1000 microM, seed germination was significantly inhibited in Arabidopsis. RNA sequencing analysis showed that melatonin regulated seed germination correlated to phytohormones abscisic acid (ABA), gibberellin (GA), and auxin. Further investigation revealed that ABA and melatonin synergistically inhibited seed germination, while GA and auxin antagonized the inhibitory effect of seed germination by melatonin. Disruption of the melatonin biosynthesis enzyme gene serotonin N-acetyltransferase (SNAT) or N-acetylserotonin methyltransferase (ASMT) promoted seed germination, while overexpression of ASMT inhibited seed germination. Taken together, our study sheds new light on the function and mechanism of melatonin in modulating seed germination in Arabidopsis.
PMID: 33811388
New Phytol , IF:8.512 , 2021 Apr doi: 10.1111/nph.17427
HEXOKINASE1 signalling promotes shoot branching and interacts with cytokinin and strigolactone pathways.
School of Biological Sciences, The University of Queensland, St. Lucia, QLD, 4072, Australia.; Universite Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, 49000, Angers, France.; Department of Pharmaceutical Biology, Julius-von-Sachs-Institute, Biocenter, Julius-Maximilians-Universitat Wurzburg, Wurzburg, 97082, Germany.
Plant architecture is controlled by several endogenous signals including hormones and sugars. However, only little is known about the nature and roles of the sugar signalling pathways in this process. Here we test whether the sugar signalling pathway mediated by HEXOKINASE1 (HXK1) is involved in the control of shoot branching. To test the involvement of HXK1 in shoot branching and in the hormonal network controlling this process, we modulated the HXK1 pathway using physiological and genetic approaches in rose, pea and arabidopsis. Mannose-induced HXK signalling triggered bud outgrowth in rose and pea. In arabidopsis, both HXK1 deficiency and defoliation led to decreased shoot branching and conferred hypersensitivity to auxin. Complementation of the HXK1 knockout mutant gin2 with a catalytically inactive HXK1, restored shoot branching to the wild-type level. HXK1-deficient plants displayed decreased cytokinin levels and increased expression of MAX2, which is required for strigolactone signalling. The branching phenotype of HXK1-deficient plants could be partly restored by cytokinin treatment and strigolactone deficiency could override the negative impact of HXK1 deficiency on shoot branching. Our observations demonstrate that HXK1 signalling contributes to the regulation of shoot branching and interacts with hormones to modulate plant architecture.
PMID: 33909299
New Phytol , IF:8.512 , 2021 Apr doi: 10.1111/nph.17402
NCP2/RHD4/SAC7, SAC6 and SAC8 phosphoinositide phosphatases are required for PtdIns4P and PtdIns(4,5)P2 homeostasis and Arabidopsis development.
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.; University of Chinese Academy of Sciences, Beijing, 100049, China.; Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.; Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.
Phosphoinositides play important roles in plant growth and development. Several SAC domain phosphoinositide phosphatases have been reported to be important for plant development. Here, we show functional analysis of SUPPRESSOR OF ACTIN 6 (SAC6) to SAC8 in Arabidopsis, a subfamily of phosphoinositide phosphatases containing SAC-domain and two transmembrane motifs. We isolated an Arabidopsis mutant ncp2 that lacked cotyledons in seedling and embryo in pid, a background defective in auxin signaling and transport. NCP2 encodes RHD4/SAC7 phosphoinositide phosphatase. SAC6, SAC7 and SAC8 exhibit overlapping and specific expression patterns in seedling and embryo. The sac6 sac7 embryos either fail to develop into seeds, or have three or four cotyledons. The embryo development of sac7 sac8 and sac6 sac7 sac8 mutants is significantly delayed or lethal, and the seedlings are arrested at early stages. Auxin maxima are decreased in double and triple sac mutants. The contents of PtdIns4P and PtdIns(4,5)P2 in sac6 sac7 and sac7 sac8 mutants are dramatically increased. Protein trafficking of the plasma membrane (PM)-localized protein PIN1 and PIN2 from trans-Golgi network/early endosome back to PM is delayed in sac7 sac8 mutants. These results indicate that SAC6-SAC8 are essential for maintaining homeostasis of PtdIns4P and PtdIns(4,5)P2, and auxin-mediated development in Arabidopsis.
PMID: 33876422
New Phytol , IF:8.512 , 2021 Apr , V230 (1) : P228-243 doi: 10.1111/nph.17144
Modulation of Arabidopsis root growth by specialized triterpenes.
Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, Ghent, 9052, Belgium.; VIB Center for Plant Systems Biology, Technologiepark 71, Ghent, 9052, Belgium.; Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Colney Lane, Norwich,, NR4 7UH, UK.; Laboratory of Molecular Cell Biology, KU Leuven, Kasteelpark Arenberg 31, Leuven, 3000, Belgium.; VIB Center for Microbiology, Kasteelpark Arenberg 31, Leuven, 3000, Belgium.; Department of Organic Chemistry, Institute of Chemistry, Sao Paulo State University (UNESP), Araraquara, Sao Paulo, 14800-060, Brazil.; Laboratory of Growth Regulators, Institute of Experimental Botany of the Czech Academy of Sciences and Faculty of Science of Palacky University, Slechtitelu 27, Olomouc, CZ-78371, Czech Republic.; Department of Organic Chemistry, Ghent University, Ghent, 9000, Belgium.; Department of Forest Genetics and Plant Physiology, Umea Plant Science Centre, Swedish University of Agricultural Sciences, Umea, SE-901 83, Sweden.; Lab of Plant Growth Analysis, Ghent University Global Campus, Incheon, 21985, Korea.
Plant roots are specialized belowground organs that spatiotemporally shape their development in function of varying soil conditions. This root plasticity relies on intricate molecular networks driven by phytohormones, such as auxin and jasmonate (JA). Loss-of-function of the NOVEL INTERACTOR OF JAZ (NINJA), a core component of the JA signaling pathway, leads to enhanced triterpene biosynthesis, in particular of the thalianol gene cluster, in Arabidopsis thaliana roots. We have investigated the biological role of thalianol and its derivatives by focusing on Thalianol Synthase (THAS) and Thalianol Acyltransferase 2 (THAA2), two thalianol cluster genes that are upregulated in the roots of ninja mutant plants. THAS and THAA2 activity was investigated in yeast, and metabolite and phenotype profiling of thas and thaa2 loss-of-function plants was carried out. THAA2 was shown to be responsible for the acetylation of thalianol and its derivatives, both in yeast and in planta. In addition, THAS and THAA2 activity was shown to modulate root development. Our results indicate that the thalianol pathway is not only controlled by phytohormonal cues, but also may modulate phytohormonal action itself, thereby affecting root development and interaction with the environment.
PMID: 33616937
New Phytol , IF:8.512 , 2021 Apr , V230 (2) : P550-566 doi: 10.1111/nph.17205
The Arabidopsis R-SNARE VAMP714 is essential for polarisation of PIN proteins and auxin responses.
Department of Biosciences, Durham University, South Road, Durham, DH1 3LE, UK.; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.
The plant hormone auxin and its directional intercellular transport play a major role in diverse aspects of plant growth and development. The establishment of auxin gradients requires the asymmetric distribution of members of the auxin efflux carrier PIN-FORMED (PIN) protein family to the plasma membrane. An endocytic pathway regulates the recycling of PIN proteins between the plasma membrane and endosomes, providing a mechanism for dynamic localisation. N-Ethylmaleimide-sensitive factor adaptor protein receptors (SNAP receptors, SNAREs) mediate fusion between vesicles and target membranes and are classed as Q- or R-SNAREs based on their sequence. We analysed gain- and loss-of-function mutants, dominant-negative transgenics and localisation of the Arabidopsis R-SNARE VAMP714 protein to understand its function. We demonstrate that VAMP714 is essential for the insertion of PINs into the plasma membrane, for polar auxin transport, root gravitropism and morphogenesis. VAMP714 gene expression is upregulated by auxin, and the VAMP714 protein co-localises with endoplasmic reticulum and Golgi vesicles and with PIN proteins at the plasma membrane. It is proposed that VAMP714 mediates the delivery of PIN-carrying vesicles to the plasma membrane, and that this forms part of a positive regulatory loop in which auxin activates a VAMP714-dependent PIN/auxin transport system to control development.
PMID: 33454983
New Phytol , IF:8.512 , 2021 Apr , V230 (2) : P535-549 doi: 10.1111/nph.17183
New fluorescent auxin probes visualise tissue-specific and subcellular distributions of auxin in Arabidopsis.
Laboratory of Growth Regulators, Faculty of Science, Palacky University and Institute of Experimental Botany, The Czech Academy of Sciences, Slechtitelu 27, Olomouc, CZ-78371, Czech Republic.; Department of Forest Genetics and Plant Physiology, Umea Plant Science Centre, Swedish University of Agricultural Sciences, Umea, SE-90183, Sweden.; School of Life Sciences, The University of Warwick, Coventry, CV4 7AL, UK.; Centre for Plant Sciences, University of Leeds, Leeds, LS2 9JT, UK.; Department of Chemical Biology, Faculty of Science, Palacky University, Slechtitelu 27, Olomouc, CZ-78371, Czech Republic.
In a world that will rely increasingly on efficient plant growth for sufficient food, it is important to learn about natural mechanisms of phytohormone action. In this work, the introduction of a fluorophore to an auxin molecule represents a sensitive and non-invasive method to directly visualise auxin localisation with high spatiotemporal resolution. The state-of-the-art multidisciplinary approaches of genetic and chemical biology analysis together with live cell imaging, liquid chromatography-mass spectrometry (LC-MS) and surface plasmon resonance (SPR) methods were employed for the characterisation of auxin-related biological activity, distribution and stability of the presented compounds in Arabidopsis thaliana. Despite partial metabolisation in vivo, these fluorescent auxins display an uneven and dynamic distribution leading to the formation of fluorescence maxima in tissues known to concentrate natural auxin, such as the concave side of the apical hook. Importantly, their distribution is altered in response to different exogenous stimuli in both roots and shoots. Moreover, we characterised the subcellular localisation of the fluorescent auxin analogues as being present in the endoplasmic reticulum and endosomes. Our work provides powerful tools to visualise auxin distribution within different plant tissues at cellular or subcellular levels and in response to internal and environmental stimuli during plant development.
PMID: 33438224
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 Apr doi: 10.1101/cshperspect.a040014
Uncovering How Auxin Optimizes Root Systems Architecture in Response to Environmental Stresses.
Plant and Crop Sciences, School of Biosciences, Sutton Bonington Campus, The University of Nottingham, Loughborough LE12 5RD, United Kingdom.
Since colonizing land, plants have developed mechanisms to tolerate a broad range of abiotic stresses that include flooding, drought, high salinity, and nutrient limitation. Roots play a key role acclimating plants to these as their developmental plasticity enables them to grow toward more favorable conditions and away from limiting or harmful stresses. The phytohormone auxin plays a key role translating these environmental signals into developmental outputs. This is achieved by modulating auxin levels and/or signaling, often through cross talk with other hormone signals like abscisic acid (ABA) or ethylene. In our review, we discuss how auxin controls root responses to water, osmotic and nutrient-related stresses, and describe how the synthesis, degradation, transport, and response of this key signaling hormone helps optimize root architecture to maximize resource acquisition while limiting the impact of abiotic stresses.
PMID: 33903159
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 Apr doi: 10.1101/cshperspect.a039990
Auxin Interactions with Other Hormones in Plant Development.
Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina 27695, USA.
Auxin is a crucial growth regulator that governs plant development and responses to environmental perturbations. It functions at the heart of many developmental processes, from embryogenesis to organ senescence, and is key to plant interactions with the environment, including responses to biotic and abiotic stimuli. As remarkable as auxin is, it does not act alone, but rather solicits the help of, or is solicited by, other endogenous signals, including the plant hormones abscisic acid, brassinosteroids, cytokinins, ethylene, gibberellic acid, jasmonates, salicylic acid, and strigolactones. The interactions between auxin and other hormones occur at multiple levels: hormones regulate one another's synthesis, transport, and/or response; hormone-specific transcriptional regulators for different pathways physically interact and/or converge on common target genes; etc. However, our understanding of this crosstalk is still fragmentary, with only a few pieces of the gigantic puzzle firmly established. In this review, we provide a glimpse into the complexity of hormone interactions that involve auxin, underscoring how patchy our current understanding is.
PMID: 33903155
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 Apr doi: 10.1101/cshperspect.a039925
Auxin Does the SAMba: Auxin Signaling in the Shoot Apical Meristem.
Laboratoire Reproduction et Developpement des Plantes, University at Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, 69342 Lyon, France.; Functional Genomics and Proteomics, National Centre for Biomolecula Research, Faculty of Science, Masaryk University and CEITEC MU, 62500 Brno, Czech Republic.
Plants, in contrast to animals, are unique in their capacity to postembryonically develop new organs due to the activity of stem cell populations, located in specialized tissues called meristems. Above ground, the shoot apical meristem generates aerial organs and tissues throughout plant life. It is well established that auxin plays a central role in the functioning of the shoot apical meristem. Auxin distribution in the meristem is not uniform and depends on the interplay between biosynthesis, transport, and degradation. Auxin maxima and minima are created, and result in transcriptional outputs that drive the development of new organs and contribute to meristem maintenance. To uncover and understand complex signaling networks such as the one regulating auxin responses in the shoot apical meristem remains a challenge. Here, we will discuss our current understanding and point to important research directions for the future.
PMID: 33903154
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 Apr doi: 10.1101/cshperspect.a039909
The Story of Auxin-Binding Protein 1 (ABP1).
School of Life Sciences, University of Warwick, Coventry CV4 7AS, United Kingdom.
The auxin-binding protein 1 (ABP1) has endured a history of undulating prominence as a candidate receptor for this important phytohormone. Its capacity for binding auxin has not been in doubt, a feature adequately explained by its crystal structure, but any relevance of this to auxin signaling and plant development has been far more demanding to define. Over its research lifetime, it has been associated with many auxin-induced activities, including ion fluxes across the plasma membrane, rearrangement of the cytoskeleton and cell shape, and the abundance of PIN proteins at the plasma membrane via control of endocytosis, all of which required its presence in the apoplast. Yet, ABP1 has a KDEL sequence that targets it to the endoplasmic reticulum, where most of it remains. This mismatch has been more than adequately compensated for by the need for an auxin receptor to account for responses far too rapid to be executed through transcription and translation and the TIR1/AuxIAA coreceptor system. However, discoveries showing that abp1-null mutants are not compromised for auxin signaling or development, that TIR1 or AFB1 are necessarily involved with very rapid responses at the plasma membrane, and that these rapid responses are mediated with intracellular auxin all suggest that ABP1's auxin-binding capacity is not physiologically relevant. Nevertheless, ABP1 is ubiquitous in higher plants and throughout plant tissues. We need to complete its history by defining its function inside plant cells.
PMID: 33903152
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 Apr doi: 10.1101/cshperspect.a040006
Casting the Net-Connecting Auxin Signaling to the Plant Genome.
Department of Stem Cell Biology, Centre for Organismal Studies, Heidelberg University, D-69120 Heidelberg, Germany.
Auxin represents one of the most potent and most versatile hormonal signals in the plant kingdom. Built on a simple core of only a few dedicated components, the auxin signaling system plays important roles for diverse aspects of plant development, physiology, and defense. Key to the diversity of context-dependent functional outputs generated by cells in response to this small molecule are gene duplication events and sub-functionalization of signaling components on the one hand, and a deep embedding of the auxin signaling system into complex regulatory networks on the other hand. Together, these evolutionary innovations provide the mechanisms to allow each cell to display a highly specific auxin response that suits its individual requirements. In this review, we discuss the regulatory networks connecting auxin with a large number of diverse pathways at all relevant levels of the signaling system ranging from biosynthesis to transcriptional response.
PMID: 33903151
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 Apr , V13 (4) doi: 10.1101/cshperspect.a040030
Auxin-Environment Integration in Growth Responses to Forage for Resources.
Universidad de Buenos Aires, Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Instituto de Investigaciones Fisiologicas y Ecologicas Vinculadas a la Agricultura (IFEVA), Facultad de Agronomia, Buenos Aires 1417, Argentina.; Fundacion Instituto Leloir and IIBBA-CONICET, Buenos Aires C1405BWE, Argentina.; Centro de Biotecnologia Vegetal, Facultad de Ciencias de la Vida, Universidad Andres Bello and Millennium Institute for Integrative Biology (iBio), Santiago 8370146, Chile.
Plant fitness depends on the adequate morphological adjustment to the prevailing conditions of the environment. Therefore, plants sense environmental cues through their life cycle, including the presence of full darkness, light, or shade, the range of ambient temperatures, the direction of light and gravity vectors, and the presence of water and mineral nutrients (such as nitrate and phosphate) in the soil. The environmental information impinges on different aspects of the auxin system such as auxin synthesis, degradation, transport, perception, and downstream transcriptional regulation to modulate organ growth. Although a single environmental cue can affect several of these points, the relative impacts differ significantly among the various growth processes and cues. While stability in the generation of precise auxin gradients serves to guide the basic developmental pattern, dynamic changes in the auxin system fine-tune body shape to optimize the capture of environmental resources.
PMID: 33431585
Cold Spring Harb Perspect Biol , IF:7.64 , 2021 Apr , V13 (4) doi: 10.1101/cshperspect.a039966
An Essential Function for Auxin in Embryo Development.
Mendel Centre for Genomics and Proteomics of Plants Systems, CEITEC MU - Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic.
Embryogenesis in seed plants is the process during which a single cell develops into a mature multicellular embryo that encloses all the modules and primary patterns necessary to build the architecture of the new plant after germination. This process involves a series of cell divisions and coordinated cell fate determinations resulting in the formation of an embryonic pattern with a shoot-root axis and cotyledon(s). The phytohormone auxin profoundly controls pattern formation during embryogenesis. Auxin functions in the embryo through its maxima/minima distribution, which acts as an instructive signal for tissue specification and organ initiation. In this review, we describe how disruptions of auxin biosynthesis, transport, and response severely affect embryo development. Also, the mechanism of auxin action in the development of the shoot-root axis and the three-tissue system is discussed with recent findings. Biological tools that can be implemented to study the auxin function during embryo development are presented, as they may be of interest to the reader.
PMID: 33431580
Plant Physiol , IF:6.902 , 2021 Apr doi: 10.1093/plphys/kiab179
Neofunctionalization of a Polyploidization-Activated Cotton Long intergenic non-coding RNA DAN1 During Drought Stress Regulation.
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, Cotton Hybrid R & D Engineering Center (the Ministry of Education), College of Agriculture, Nanjing Agricultural University, Nanjing, 210095, China.; College of Agriculture, Xinjiang Agricultural University, Engineering Research Center of Ministry of Cotton Education, 311 Nongda East Road, Urumqi, 830052, P. R. China.
The genomic shock of whole-genome duplication and hybridization introduces great variation into transcriptomes, for both coding and non-coding genes. An altered transcriptome provides a molecular basis for improving adaptation during the evolution of new species. The allotetraploid cotton, together with the putative diploid ancestor species compose a fine model for study the rapid gene neofunctionalization over the genome shock. Here we report on Drought-Associated Non-coding gene 1 (DAN1), a long intergenic non-coding RNA (lincRNA) that arose from the cotton progenitor A-diploid genome after hybridization and whole-genome duplication events during cotton evolution. DAN1 in allotetraploid upland cotton (Gossypium hirsutum, Gh) is a drought-responsive lincRNA predominantly expressed in nucleoplasm. A chromatin isolation by RNA purification (ChIRP) profiling and electrophoretic mobility shift assay (EMSA) analysis demonstrated that GhDAN1 RNA can bind with DNA fragments containing AAAG motifs, similar to DNA-binding one zinc finger (Dof) transcription factor binding sequences. The suppression of GhDAN1 mainly regulates genes with AAAG motifs in auxin-response pathways, which are associated with drought stress regulation. As a result, GhDAN1-silenced plants exhibit improved tolerance to drought stress. This phenotype resembles the drought-tolerant phenotype of the A-diploid cotton ancestor species, which has an undetectable expression of DAN1. The role of DAN1 in cotton evolution and drought tolerance regulation suggests that the genomic shock of interspecific hybridization and whole-genome duplication (WGD) stimulated neofunctionalization of non-coding genes during the natural evolutionary process.
PMID: 33871645
Plant Physiol , IF:6.902 , 2021 Apr doi: 10.1093/plphys/kiab171
HEAT SHOCK PROTEIN 90 proteins and YODA regulate main body axis formation during early embryogenesis.
Centre of the Region Hana for Biotechnological and Agricultural Research, Faculty of Science, Palacky University Olomouc, Slechtitelu 27, 783 71 Olomouc, Czech Republic.; Institute of Experimental Botany (IEB), Czech Acad Sci, Centre of the Region Hana for Biotechnological and Agricultural Research (CRH), Slechtitelu 31, 779 00, Olomouc, Czech Republic.
The YODA kinase (YDA) pathway is intimately associated with the control of Arabidopsis (Arabidopsis thaliana) embryo development, but little is known regarding its regulators. Using genetic analysis, HEAT SHOCK PROTEIN 90 (HSP90) proteins emerge as potent regulators of YDA in the process of embryo development and patterning. This study is focused on the characterization and quantification of early embryonal traits of single and double hsp90 and yda mutants. HSP90s genetic interactions with YDA affected the downstream signaling pathway to control the development of both basal and apical cell lineage of embryo. Our results demonstrate that the spatiotemporal expression of WUSCHEL-RELATED HOMEOBOX 8 (WOX8) and WOX2 is changed when function of HSP90s or YDA is impaired, suggesting their essential role in the cell fate determination and possible link to auxin signaling during early embryo development. Hence, HSP90s together with YDA signaling cascade affect transcriptional networks shaping the early embryo development.
PMID: 33856486
Plant Physiol , IF:6.902 , 2021 Apr , V185 (3) : P757-758 doi: 10.1093/plphys/kiaa099
Filling the grain: transcription factor OsNF-YB1 triggers auxin biosynthesis to boost rice grain size.
Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom.
PMID: 33822224
Plant Physiol , IF:6.902 , 2021 Apr , V185 (3) : P1059-1075 doi: 10.1093/plphys/kiaa087
Gibberellin and auxin signaling genes RGA1 and ARF8 repress accessory fruit initiation in diploid strawberry.
Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742, USA.
Unlike ovary-derived botanical fruits, strawberry (Fragaria x ananassa) is an accessory fruit derived from the receptacle, the stem tip subtending floral organs. Although both botanical and accessory fruits initiate development in response to auxin and gibberellic acid (GA) released from seeds, the downstream auxin and GA signaling mechanisms underlying accessory fruit development are presently unknown. We characterized GA and auxin signaling mutants in wild strawberry (Fragaria vesca) during early stage fruit development. While mutations in FveRGA1 and FveARF8 both led to the development of larger fruit, only mutations in FveRGA1 caused parthenocarpic fruit formation, suggesting FveRGA1 is a key regulator of fruit set. FveRGA1 mediated fertilization-induced GA signaling during accessory fruit initiation by repressing the expression of cell division and expansion genes and showed direct protein-protein interaction with FveARF8. Further, fvearf8 mutant fruits exhibited an enhanced response to auxin or GA application, and the increased response to GA was due to increased expression of FveGID1c coding for a putative GA receptor. The work reveals a crosstalk mechanism between FveARF8 in auxin signaling and FveGID1c in GA signaling. Together, our work provides functional insights into hormone signaling in an accessory fruit, broadens our understanding of fruit initiation in different fruit types, and lays the groundwork for future improvement of strawberry fruit productivity and quality.
PMID: 33793929
Plant Physiol , IF:6.902 , 2021 Apr , V185 (3) : P1198-1215 doi: 10.1093/plphys/kiaa093
Gibberellin signaling mediates lateral root inhibition in response to K+-deprivation.
Department of Biosciences, Durham University, Durham DH1 3LE, UK.
The potassium ion (K+) is vital for plant growth and development, and K+-deprivation leads to reduced crop yields. Here we describe phenotypic, transcriptomic, and mutant analyses to investigate the signaling mechanisms mediating root architectural changes in Arabidopsis (Arabidopsis thaliana) Columbia. We showed effects on root architecture are mediated through a reduction in cell division in the lateral root (LR) meristems, the rate of LR initiation is reduced but LR density is unaffected, and primary root growth is reduced only slightly. This was primarily regulated through gibberellic acid (GA) signaling, which leads to the accumulation of growth-inhibitory DELLA proteins. The short LR phenotype was rescued by exogenous application of GA but not of auxin or by the inhibition of ethylene signaling. RNA-seq analysis showed upregulation by K+-deprivation of the transcription factors JUNGBRUNNEN1 (JUB1) and the C-repeat-binding factor (CBF)/dehydration-responsive element-binding factor 1 regulon, which are known to regulate GA signaling and levels that regulate DELLAs. Transgenic overexpression of JUB1 and CBF1 enhanced responses to K+ stress. Attenuation of the reduced LR growth response occurred in mutants of the CBF1 target gene SFR6, implicating a role for JUB1, CBF1, and SFR6 in the regulation of LR growth in response to K+-deprivation via DELLAs. We propose this represents a mechanism to limit horizontal root growth in conditions where K+ is available deeper in the soil.
PMID: 33793923
Plant Physiol , IF:6.902 , 2021 Apr , V185 (3) : P1166-1181 doi: 10.1093/plphys/kiaa072
Coordinated cytokinin signaling and auxin biosynthesis mediates arsenate-induced root growth inhibition.
State Key Laboratory of Crop Biology, College of Agronomy, Shandong Agricultural University, Tai'an 271018, China.; State Key Laboratory of Plant Genomics, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.; CAS Center for Excellence in Biotic Interactions, University of Chinese Academy of Sciences, Beijing 100049, China.
Interactions between plant hormones and environmental signals are important for the maintenance of root growth plasticity under ever-changing environmental conditions. Here, we demonstrate that arsenate (AsV), the most prevalent form of arsenic (As) in nature, restrains elongation of the primary root through transcriptional regulation of local auxin biosynthesis genes in the root tips of Arabidopsis (Arabidopsis thaliana) plants. The ANTHRANILATE SYNTHASE ALPHA SUBUNIT 1 (ASA1) and BETA SUBUNIT 1 (ASB1) genes encode enzymes that catalyze the conversion of chorismate to anthranilate (ANT) via the tryptophan-dependent auxin biosynthesis pathway. Our results showed that AsV upregulates ASA1 and ASB1 expression in root tips, and ASA1- and ASB1-mediated auxin biosynthesis is involved in AsV-induced root growth inhibition. Further investigation confirmed that AsV activates cytokinin signaling by stabilizing the type-B ARABIDOPSIS RESPONSE REGULATOR1 (ARR1) protein, which directly promotes the transcription of ASA1 and ASB1 genes by binding to their promoters. Genetic analysis revealed that ASA1 and ASB1 are epistatic to ARR1 in the AsV-induced inhibition of primary root elongation. Overall, the results of this study illustrate a molecular framework that explains AsV-induced root growth inhibition via crosstalk between two major plant growth regulators, auxin and cytokinin.
PMID: 33793921
Plant Physiol , IF:6.902 , 2021 Apr , V185 (4) : P1500-1522 doi: 10.1093/plphys/kiaa119
Hormonal impact on photosynthesis and photoprotection in plants.
Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain.
Photosynthesis is not only essential for plants, but it also sustains life on Earth. Phytohormones play crucial roles in developmental processes, from organ initiation to senescence, due to their role as growth and developmental regulators, as well as their central role in the regulation of photosynthesis. Furthermore, phytohormones play a major role in photoprotection of the photosynthetic apparatus under stress conditions. Here, in addition to discussing our current knowledge on the role of the phytohormones auxin, cytokinins, gibberellins, and strigolactones in promoting photosynthesis, we will also highlight the role of abscisic acid beyond stomatal closure in modulating photosynthesis and photoprotection under various stress conditions through crosstalk with ethylene, salicylates, jasmonates, and brassinosteroids. Furthermore, the role of phytohormones in controlling the production and scavenging of photosynthesis-derived reactive oxygen species, the duration and extent of photo-oxidative stress and redox signaling under stress conditions will be discussed in detail. Hormones have a significant impact on the regulation of photosynthetic processes in plants under both optimal and stress conditions, with hormonal interactions, complementation, and crosstalk being important in the spatiotemporal and integrative regulation of photosynthetic processes during organ development at the whole-plant level.
PMID: 33793915
Plant Physiol , IF:6.902 , 2021 Apr , V185 (3) : P934-950 doi: 10.1093/plphys/kiaa057
OsYUC11-mediated auxin biosynthesis is essential for endosperm development of rice.
Jiangsu Key Laboratory of Crop Genetics and Physiology, College of Agriculture, Yangzhou University, Yangzhou 225009, China.; Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China.; Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, College of Agriculture, Yangzhou University, Yangzhou 225009, China.; Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, College of Agriculture, Yangzhou University, Yangzhou 225009, China.; Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China.
Auxin is a phytohormone essential for plant development. However, our understanding of auxin-regulated endosperm development remains limited. Here, we described rice YUCCA (YUC) flavin-containing monooxygenase encoding gene OsYUC11 as a key contributor to auxin biosynthesis in rice (Oryza sativa) endosperm. Grain filling or storage product accumulation was halted by mutation of OsYUC11, but the deficiencies could be recovered by the exogenous application of auxin. A rice transcription factor (TF) yeast library was screened, and 41 TFs that potentially bind to the OsYUC11 promoter were identified, of which OsNF-YB1, a member of the nuclear factor Y family, is predominantly expressed in the endosperm. Both osyuc11 and osnf-yb1 mutants exhibited reduced seed size and increased chalkiness, accompanied by a reduction in indole-3-acetic acid biosynthesis. OsNF-YB1 can bind the OsYUC11 promoter to induce gene expression in vivo. We also found that OsYUC11 was a dynamically imprinted gene that predominantly expressed the paternal allele in the endosperm up to 10 d after fertilization (DAF) but then became a non-imprinted gene at 15 DAF. A functional maternal allele of OsYUC11 was able to recover the paternal defects of this gene. Overall, the findings indicate that OsYUC11-mediated auxin biosynthesis is essential for endosperm development in rice.
PMID: 33793908
Plant Physiol , IF:6.902 , 2021 Apr , V185 (3) : P1039-1058 doi: 10.1093/plphys/kiaa085
The nucleolar protein SAHY1 is involved in pre-rRNA processing and normal plant growth.
Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan.; Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.; Department of Biological Science and Technology, National Pingtung University of Science and Technology, Neipu, Pingtung County,Taiwan.
Although the nucleolus is involved in ribosome biogenesis, the functions of numerous nucleolus-localized proteins remain unclear. In this study, we genetically isolated Arabidopsis thaliana salt hypersensitive mutant 1 (sahy1), which exhibits slow growth, short roots, pointed leaves, and sterility. SAHY1 encodes an uncharacterized protein that is predominantly expressed in root tips, early developing seeds, and mature pollen grains and is mainly restricted to the nucleolus. Dysfunction of SAHY1 primarily causes the accumulation of 32S, 18S-A3, and 27SB pre-rRNA intermediates. Coimmunoprecipitation experiments further revealed the interaction of SAHY1 with ribosome proteins and ribosome biogenesis factors. Moreover, sahy1 mutants are less sensitive to protein translation inhibitors and show altered expression of structural constituents of ribosomal genes and ribosome subunit profiles, reflecting the involvement of SAHY1 in ribosome composition and ribosome biogenesis. Analyses of ploidy, S-phase cell cycle progression, and auxin transport and signaling indicated the impairment of mitotic activity, translation of auxin transport carrier proteins, and expression of the auxin-responsive marker DR5::GFP in the root tips or embryos of sahy1 plants. Collectively, these data demonstrate that SAHY1, a nucleolar protein involved in ribosome biogenesis, plays critical roles in normal plant growth in association with auxin transport and signaling.
PMID: 33793900
Plant Physiol , IF:6.902 , 2021 Apr , V185 (4) : P1381-1394 doi: 10.1093/plphys/kiaa001
Subtilase activity in intrusive cells mediates haustorium maturation in parasitic plants.
RIKEN Center for Sustainable Resource Science, Yokohama 230-0045, Japan.; Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan.; Department of Plant Physiology and Biochemistry, University of Hohenheim, Stuttgart 70599, Germany.; Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan.; PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.; RIKEN BioResource Research Center, Tsukuba, Ibaraki 305-0074, Japan.
Parasitic plants that infect crops are devastating to agriculture throughout the world. These parasites develop a unique inducible organ called the haustorium that connects the vascular systems of the parasite and host to establish a flow of water and nutrients. Upon contact with the host, the haustorial epidermal cells at the interface with the host differentiate into specific cells called intrusive cells that grow endophytically toward the host vasculature. Following this, some of the intrusive cells re-differentiate to form a xylem bridge (XB) that connects the vasculatures of the parasite and host. Despite the prominent role of intrusive cells in host infection, the molecular mechanisms mediating parasitism in the intrusive cells remain poorly understood. In this study, we investigated differential gene expression in the intrusive cells of the facultative parasite Phtheirospermum japonicum in the family Orobanchaceae by RNA-sequencing of laser-microdissected haustoria. We then used promoter analyses to identify genes that are specifically induced in intrusive cells, and promoter fusions with genes encoding fluorescent proteins to develop intrusive cell-specific markers. Four of the identified intrusive cell-specific genes encode subtilisin-like serine proteases (SBTs), whose biological functions in parasitic plants are unknown. Expression of SBT inhibitors in intrusive cells inhibited both intrusive cell and XB development and reduced auxin response levels adjacent to the area of XB development. Therefore, we propose that subtilase activity plays an important role in haustorium development in P. japonicum.
PMID: 33793894
Plant Physiol , IF:6.902 , 2021 Apr , V185 (3) : P1021-1038 doi: 10.1093/plphys/kiaa084
Expression of a plastid-localized sugar transporter in the suspensor is critical to embryogenesis.
College of Plant Protection, The Key Laboratory of Plant Immunity, Nanjing Agriculture University, Nanjing 210095, China.; State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.; Division of Biochemistry, University of Missouri, Columbia, MO 65211, USA.
Plant growth and development rely on sugar transport between source and sink cells and between different organelles. The plastid-localized sugar transporter GLUCOSE-6-PHOSPHATE TRANSLOCATER1 (GPT1) is an essential gene in Arabidopsis (Arabidopsis thaliana). Using a partially rescued gpt1 mutant and cell-specific RNAi suppression of GPT1, we demonstrated that GPT1 is essential to the function of the embryo suspensor and the development of the embryo. GPT1 showed a dynamic expression/accumulation pattern during embryogenesis. Inhibition of GPT1 accumulation via RNAi using a suspensor-specific promoter resulted in embryos and seedlings with defects similar to auxin mutants. Loss of function of GPT1 in the suspensor also led to abnormal/ectopic cell division in the lower part of the suspensor, which gave rise to an ectopic embryo, resulting in twin embryos in some seeds. Furthermore, loss of function of GPT1 resulted in vacuolar localization of PIN-FORMED1 (PIN1) and altered DR5 auxin activity. Proper localization of PIN1 on the plasma membrane is essential to polar auxin transport and distribution, a key determinant of pattern formation during embryogenesis. Our findings suggest that the function of GPT1 in the embryo suspensor is linked to sugar and/or hormone distribution between the embryo proper and the maternal tissues, and is important for maintenance of suspensor identity and function during embryogenesis.
PMID: 33793862
Plant Physiol , IF:6.902 , 2021 Apr , V185 (4) : P1829-1846 doi: 10.1093/plphys/kiab026
SlERF52 regulates SlTIP1;1 expression to accelerate tomato pedicel abscission.
College of Horticulture, Shenyang Agricultural University, Shenyang, Liaoning 110866, People's Republic of China.; Key Laboratory of Protected Horticulture of Ministry of Education, Shenyang, Liaoning Province, China.; Crops Pathology and Genetic Research Unit, United States Department of Agriculture Research Service, California, USA.; Department of Plant Sciences, University of California, California, USA.
Abscission of plant organs is induced by developmental signals and diverse environmental stimuli and involves multiple regulatory networks, including biotic or abiotic stress-impaired auxin flux in the abscission zone (AZ). Depletion of auxin activates AZ ethylene (ETH) production and triggers acceleration of abscission, a process that requires hydrogen peroxide (H2O2). However, the interaction between these networks and the underlying mechanisms that control abscission are poorly understood. Here, we found that expression of tonoplast intrinsic proteins, which belong to the aquaporin (AQP) family in the AZ was important for tomato (Solanum lycopersicum) pedicel abscission. Liquid chromatography-tandem mass spectrometry and in situ hybridization revealed that SlTIP1;1 was most abundant and specifically present in the tomato pedicel AZ. SlTIP1;1 localized in the plasma membrane and tonoplast. Knockout of SlTIP1;1 resulted in delayed abscission, whereas overexpression of SlTIP1;1 accelerated abscission. Further analysis indicated that SlTIP1;1 mediated abscission via gating of cytoplasmic H2O2 concentrations and osmotic water permeability (Pf). Elevated cytoplasmic levels of H2O2 caused a suppressed auxin signal in the early abscission stage and enhanced ETH production during abscission. Furthermore, we found that increasing Pf was required to enhance the turgor pressure to supply the break force for AZ cell separation. Moreover, we observed that SlERF52 bound directly to the SlTIP1;1 promoter to regulate its expression, demonstrating a positive loop in which cytoplasmic H2O2 activates ETH production, which activates SlERF52. This, in turn, induces SlTIP1;1, which leads to elevated cytoplasmic H2O2 and water influx.
PMID: 33638643
Plant Physiol , IF:6.902 , 2021 Apr , V185 (4) : P1652-1665 doi: 10.1093/plphys/kiab006
Time-course observation of the reconstruction of stem cell niche in the intact root.
College of Life Sciences, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou 510642, China.
The stem cell niche (SCN) is critical in maintaining continuous postembryonic growth of the plant root. During their growth in soil, plant roots are often challenged by various biotic or abiotic stresses, resulting in damage to the SCN. This can be repaired by the reconstruction of a functional SCN. Previous studies examining the SCN's reconstruction often introduce physical damage including laser ablation or surgical excision. In this study, we performed a time-course observation of the SCN reconstruction in pWOX5:icals3m roots, an inducible system that causes non-invasive SCN differentiation upon induction of estradiol on Arabidopsis (Arabidopsis thaliana) root. We found a stage-dependent reconstruction of SCN in pWOX5:icals3m roots, with division-driven anatomic reorganization in the early stage of the SCN recovery, and cell fate specification of new SCN in later stages. During the recovery of the SCN, the local accumulation of auxin was coincident with the cell division pattern, exhibiting a spatial shift in the root tip. In the early stage, division mostly occurred in the neighboring stele to the SCN position, while division in endodermal layers seemed to contribute more in the later stages, when the SCN was specified. The precise re-positioning of SCN seemed to be determined by mutual antagonism between auxin and cytokinin, a conserved mechanism that also regulates damage-induced root regeneration. Our results thus provide time-course information about the reconstruction of SCN in intact Arabidopsis roots, which highlights the stage-dependent re-patterning in response to differentiated quiescent center.
PMID: 33599750
Plant Physiol , IF:6.902 , 2021 Apr , V185 (4) : P1798-1812 doi: 10.1093/plphys/kiab014
ARF2 represses expression of plant GRF transcription factors in a complementary mechanism to microRNA miR396.
Instituto de Biologia Molecular y Celular de Rosario (IBR), CONICET and Universidad Nacional de Rosario, Rosario 2000, Argentina.; Centro de Estudios Interdisciplinarios, Universidad Nacional de Rosario, Rosario 2000, Argentina.
Members of the GROWTH REGULATING FACTOR (GRF) family of transcription factors play key roles in the promotion of plant growth and development. Many GRFs are post-transcriptionally repressed by microRNA (miRNA) miR396, an evolutionarily conserved small RNA, which restricts their expression to proliferative tissue. We performed a comprehensive analysis of the GRF family in eudicot plants and found that in many species all the GRFs have a miR396-binding site. Yet, we also identified GRFs with mutations in the sequence recognized by miR396, suggesting a partial or complete release of their post-transcriptional repression. Interestingly, Brassicaceae species share a group of GRFs that lack miR396 regulation, including Arabidopsis GRF5 and GRF6. We show that instead of miR396-mediated post-transcriptional regulation, the spatiotemporal control of GRF5 is achieved through evolutionarily conserved promoter sequences, and that AUXIN RESPONSE FACTOR 2 (ARF2) binds to such conserved sequences to repress GRF5 expression. Furthermore, we demonstrate that the unchecked expression of GRF5 in arf2 mutants is responsible for the increased cell number of arf2 leaves. The results describe a switch in the repression mechanisms that control the expression of GRFs and mechanistically link the control of leaf growth by miR396, GRFs, and ARF2 transcription factors.
PMID: 33580700
Environ Pollut , IF:6.792 , 2021 Apr , V284 : P117204 doi: 10.1016/j.envpol.2021.117204
Role of miR164 in the growth of wheat new adventitious roots exposed to phenanthrene.
College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China; Institute of Botany, Jiangsu Province and Chinese Academy Sciences, Nanjing, 210014, China.; College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China.; College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA, 01003, United States.; College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China; Department of Analytical Chemistry, The Connecticut Agricultural Experiment Station, New Haven, CT, 06504, United States.; College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, 210095, People's Republic of China. Electronic address: xhzhan@njau.edu.cn.
Polycyclic aromatic hydrocarbons (PAHs), ubiquitous organic pollutants in the environment, can accumulate in humans via the food chain and then harm human health. MiRNAs (microRNAs), a kind of non-coding small RNAs with a length of 18-30 nucleotides, regulate plant growth and development and respond to environmental stress. In this study, it is demonstrated that miR164 can regulate root growth and adventitious root generation of wheat under phenanthrene exposure by targeting NAC (NAM/ATAF/CUC) transcription factor. We observed that phenanthrene treatment accelerated the senescence and death of wheat roots, and stimulated the occurrence of new roots. However, it is difficult to compensate for the loss caused by old root senescence and death, due to the slower growth of new roots under phenanthrene exposure. Phenanthrene accumulation in wheat roots caused to generate a lot of reactive oxygen species, and enhanced lipoxygenase activity and malonaldehyde concentration, meaning that lipid peroxidation is the main reason for root damage. MiR164 was up-regulated by phenanthrene, enhancing the silence of NAC1, weakening the association with auxin signal, and inhibiting the occurrence of adventitious roots. Phenanthrene also affected the expression of CDK (the coding gene of cyclin-dependent kinase) and CDC2 (a gene regulating cell division cycle), the key genes in the cell cycle of pericycle cells, thereby affecting the occurrence and growth of lateral roots. In addition, NAM (a gene regulating no apical meristem) and NAC23 may also be related to the root growth and development in wheat exposed to phenanthrene. These results provide not only theoretical basis for understanding the molecular mechanism of crop response to PAHs accumulation, but also knowledge support for improving phytoremediation of soil or water contaminated by PAHs.
PMID: 33910135
Plant J , IF:6.141 , 2021 Apr doi: 10.1111/tpj.15299
GrasVIQ: An Image Analysis Framework for Automatically Quantifying Vein Number and Morphology in Grass Leaves.
Division of Biological Sciences, Interdisciplinary Plant Group, and Missouri Maize Center, University of Missouri, Columbia, MO, 65211, USA.; Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO, 65211, USA.; Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, 06520, USA.
Beyond facilitating transport and providing mechanical support to the leaf, veins have important roles in the performance and productivity of plants and the ecosystem. In recent decades, computational image analysis has accelerated the extraction and quantification of vein traits, benefiting fields of research from agriculture to climatology. However, most of the existing leaf vein image analysis programs have been developed for the reticulate venation in dicots. Despite the agroeconomic importance of cereal grass crops, like Oryza sativa (rice) and Zea mays (maize), a dedicated image analysis program for the parallel venation in monocots has yet to be developed. To address the need for an image-based vein phenotyping tool for model and agronomic grass species, we developed the Grass Vein Image Quantification (GrasVIQ) framework. Designed specifically for parallel venation, this framework automatically segments and quantifies vein patterns from images of cleared leaf pieces using classical computer vision techniques. Using image datasets from maize inbred lines and auxin biosynthesis and transport mutants in maize, we demonstrate the utility of GrasVIQ for quantifying important vein traits, including vein density, vein width, and interveinal distance. Further, we show that the framework can resolve quantitative differences and identify vein patterning defects, which is advantageous for genetic experiments and mutant screens. We report that GrasVIQ can perform high throughput vein quantification, with precision on par with manual quantification. Therefore, we envision GrasVIQ to be adopted for vein phenomics in maize and other grass species.
PMID: 33914380
Plant J , IF:6.141 , 2021 Apr doi: 10.1111/tpj.15276
Overlapping and stress-specific transcriptomic and hormonal responses to flooding and drought in soybean.
School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, Virginia, 24061, USA.; Department of Plant Biology and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA.; Department of Pediatrics, University of Pittsburg, Pittsburg, Pennsylvania, 15224, USA.; Department of Bioscience and Biotechnology, Fukui Prefectural University, Eiheiji, Fukui, 910-1195, Japan.
Flooding and drought are serious constraints that reduce crop productivity worldwide. Previous studies identified genes conferring tolerance to both water extremes in various plants. However, overlapping responses to flooding and drought at the genome-scale remain obscure. Here, we defined overlapping and stress-specific transcriptomic and hormonal responses to submergence, drought, and recovery from these stresses in soybean (Glycine max). We performed comparative RNA-Seq and hormone profiling, identifying genes, hormones, and biological processes that are differentially regulated in an overlapping or stress-specific manner. Overlapping responses included positive regulation of trehalose and sucrose metabolism and negative regulation of cellulose, tubulin, photosystem II and I, and chlorophyll biosynthesis, facilitating the economization of energy reserves under both submergence and drought. Additional energy-consuming pathways were restricted in a stress-specific manner. Downregulation of distinct pathways for energy-saving under each stress suggests that energy-consuming processes that are relatively unnecessary for each stress adaptation are turned down. Our newly developed transcriptomic-response analysis revealed that ABA and ethylene responses were activated in common under both stresses, whereas stimulated auxin response was submergence-specific. The energy-saving strategy is the key overlapping mechanism that underpins adaptation to both submergence and drought in soybean. ABA and ethylene are candidate hormones that coordinate transcriptomic energy-saving processes under both stresses. Auxin may be a signaling component that distinguishes submergence-specific regulation of stress response.
PMID: 33864651
Plant J , IF:6.141 , 2021 Apr doi: 10.1111/tpj.15271
Iso-anchorene is an endogenous metabolite that inhibits primary root growth in Arabidopsis.
Biological and Environmental Sciences and Engineering Division, Center for Desert Agriculture, The BioActives Lab, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.; State Key Laboratory of Cotton Biology, Henan Joint International Laboratory for Crop Multi-Omics Research, School of Life Sciences, Henan University, Jinming Road, Kaifeng, 475004, China.; Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
Carotenoid-derived regulatory metabolites and hormones are generally known to arise through the oxidative cleavage of a single double bond in the carotenoid backbone, which yields mono-carbonyl products called apocarotenoids. However, the extended conjugated double bond system of these pigments predestines them also to repeated cleavage forming dialdehyde products, diapocarotenoids, which have been less investigated due to their instability and low abundance. Recently, we reported on the short diapocarotenoid anchorene as an endogenous Arabidopsis metabolite and specific signaling molecule that promotes anchor root formation. In this work, we investigated the biological activity of a synthetic isomer of anchorene, iso-anchorene, which can be derived from repeated carotenoid cleavage. We show that iso-anchorene is a growth inhibitor that specifically inhibits primary root growth by reducing cell division rates in the root apical meristem. Using auxin efflux transporter marker lines, we also show that the effect of iso-anchorene on primary root growth involves the modulation of auxin homeostasis. Moreover, by using liquid chromatography-mass spectrometry analysis, we demonstrate that iso-anchorene is a natural Arabidopsis metabolite. Chemical inhibition of carotenoid biosynthesis led to a significant decrease in the iso-anchorene level, indicating that it originates from this metabolic pathway. Taken together, our results reveal a novel carotenoid-derived regulatory metabolite with a specific biological function that affects root growth, manifesting the biological importance of diapocarotenoids.
PMID: 33837613
Plant J , IF:6.141 , 2021 Apr , V106 (2) : P326-335 doi: 10.1111/tpj.15184
Plant stem cell research is uncovering the secrets of longevity and persistent growth.
Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, 630-0192, Japan.; Department of Biology, Faculty of Science, Niigata University, Niigata, 950-2181, Japan.; National Institute for Basic Biology, Okazaki, 444-8585, Japan.; Department of Basic Biology, The Graduate University for Advanced Studies (SOKENDAI), Okazaki, 444-8585, Japan.; Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502, Japan.; Graduate School of Life Sciences, Tohoku University, Sendai, 980-8577, Japan.; Howard Hughes Medical Institute and Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX, 78712, USA.; Institute of Transformative Biomolecules (WPI-ITbM), Nagoya University, Nagoya, 464-8601, Japan.; Department of Biology, Faculty of Science, Kyushu University, Fukuoka, 819-0395, Japan.; Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602, Japan.; Sugashima Marine Biological Laboratory, Graduate School of Science, Nagoya University, Toba, 517-0004, Japan.; Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.
Plant stem cells have several extraordinary features: they are generated de novo during development and regeneration, maintain their pluripotency, and produce another stem cell niche in an orderly manner. This enables plants to survive for an extended period and to continuously make new organs, representing a clear difference in their developmental program from animals. To uncover regulatory principles governing plant stem cell characteristics, our research project 'Principles of pluripotent stem cells underlying plant vitality' was launched in 2017, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Japanese government. Through a collaboration involving 28 research groups, we aim to identify key factors that trigger epigenetic reprogramming and global changes in gene networks, and thereby contribute to stem cell generation. Pluripotent stem cells in the shoot apical meristem are controlled by cytokinin and auxin, which also play a crucial role in terminating stem cell activity in the floral meristem; therefore, we are focusing on biosynthesis, metabolism, transport, perception, and signaling of these hormones. Besides, we are uncovering the mechanisms of asymmetric cell division and of stem cell death and replenishment under DNA stress, which will illuminate plant-specific features in preserving stemness. Our technology support groups expand single-cell omics to describe stem cell behavior in a spatiotemporal context, and provide correlative light and electron microscopic technology to enable live imaging of cell and subcellular dynamics at high spatiotemporal resolution. In this perspective, we discuss future directions of our ongoing projects and related research fields.
PMID: 33533118
J Exp Bot , IF:5.908 , 2021 Apr doi: 10.1093/jxb/erab177
Integrating transcriptome, co-expression and QTL-seq reveal metabolism of flavonoids and auxin associated with the primary root development in maize.
Jiangsu Key Laboratory of Crop Genetics and Physiology/ Key Laboratory of Plant Functional Genomics of the Ministry of Education/ Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Agricultural College of Yangzhou University, Yangzhou, China.; Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, China.; Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University.
The primary root is critical for early seedling growth and survival. To understand the molecular mechanisms governing primary root development, we performed a dynamic transcriptome analysis of two maize (Zea mays) inbred lines with contrasting primary root length (PRL) at nine time points over a 12-day period. A total of 18,702 genes were differentially expressed between two lines or different time points. Gene enrichment, phytohormone content determination, and metabolnomics analysis showed that auxin biosynthesis and signal transduction as well as the phenylpropanoid and flavonoids biosynthesis pathways were associated with root development. The co-expression network analysis revealed that eight modules were associated with lines/stages, as well as PRL or lateral root length (LRL). In root related modules, flavonoids metabolism accompanied by with auxin biosynthesis and signal transduction constituted a complex gene regulatory network during primary root development. Two candidate genes (rtcs and Zm00001d012781) involved in the auxin signaling and flavonoids biosynthesis were identified by co-expression network analysis, QTL-seq and functional annotation. These results contribute to an increased understanding of the regulatory network for PRL and LRL development, and provided a valuable gene resource for improvement of root performance in maize.
PMID: 33909071
J Exp Bot , IF:5.908 , 2021 Apr , V72 (8) : P3074-3090 doi: 10.1093/jxb/erab056
Diurnal variation of transitory starch metabolism is regulated by plastid proteins WXR1/WXR3 in Arabidopsis young seedlings.
State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China.; Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China.; Center for Crop Panomics, College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China.
Transitory starch is the portion of starch that is synthesized during the day in the chloroplast and usually used for plant growth overnight. Here, we report altered metabolism of transitory starch in the wxr1/wxr3 (weak auxin response 1/3) mutants of Arabidopsis. WXR1/WXR3 were previously reported to regulate root growth of young seedlings and affect the auxin response mediated by auxin polar transport in Arabidopsis. In this study the wxr1/wxr3 mutants accumulated transitory starch in cotyledon, young leaf, and hypocotyl at the end of night. WXR1/WXR3 expression showed diurnal variation. Grafting experiments indicated that the WXRs in root were necessary for proper starch metabolism and plant growth. We also found that photosynthesis was inhibited and the transcription level of DIN1/DIN6 (Dark-Inducible 1/6) was reduced in wxr1/wxr3. The mutants also showed a defect in the ionic equilibrium of Na+ and K+, consistent with our bioinformatics data that genes related to ionic equilibrium were misregulated in wxr1. Loss of function of WXR1 also resulted in abnormal trafficking of membrane lipids and proteins. This study reveals that the plastid proteins WXR1/WXR3 play important roles in promoting transitory starch degradation for plant growth over night, possibly through regulating ionic equilibrium in the root.
PMID: 33571997
J Exp Bot , IF:5.908 , 2021 Apr , V72 (8) : P3044-3060 doi: 10.1093/jxb/erab046
Outgrowth of the axillary bud in rose is controlled by sugar metabolism and signalling.
Universite Angers, Institut Agro, INRAE, IRHS, SFR QUASAV, 49000 Angers, France.; College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China.; Institut de Biologie Moleculaire des Plantes, Centre National de la Recherche Scientifique, Unite Propre de Recherche 2357, Conventionne avec l'Universite de Strasbourg, 67084 Strasbourg, France.; School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia.; Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universite Paris-Sud, Universite d'Evry, Universite Paris-Saclay, Batiment 630, Plateau de Moulon, 91192 Gif sur Yvette, France.; Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Universite Paris-Saclay, 78000 Versailles, France.
Shoot branching is a pivotal process during plant growth and development, and is antagonistically orchestrated by auxin and sugars. In contrast to extensive investigations on hormonal regulatory networks, our current knowledge on the role of sugar signalling pathways in bud outgrowth is scarce. Based on a comprehensive stepwise strategy, we investigated the role of glycolysis/the tricarboxylic acid (TCA) cycle and the oxidative pentose phosphate pathway (OPPP) in the control of bud outgrowth. We demonstrated that these pathways are necessary for bud outgrowth promotion upon plant decapitation and in response to sugar availability. They are also targets of the antagonistic crosstalk between auxin and sugar availability. The two pathways act synergistically to down-regulate the expression of BRC1, a conserved inhibitor of shoot branching. Using Rosa calluses stably transformed with GFP-fused promoter sequences of RhBRC1 (pRhBRC1), glycolysis/TCA cycle and the OPPP were found to repress the transcriptional activity of pRhBRC1 cooperatively. Glycolysis/TCA cycle- and OPPP-dependent regulations involve the -1973/-1611 bp and -1206/-709 bp regions of pRhBRC1, respectively. Our findings indicate that glycolysis/TCA cycle and the OPPP are integrative parts of shoot branching control and can link endogenous factors to the developmental programme of bud outgrowth, likely through two distinct mechanisms.
PMID: 33543244
Hortic Res , IF:5.404 , 2021 Apr , V8 (1) : P78 doi: 10.1038/s41438-021-00515-0
Tomato SlBL4 plays an important role in fruit pedicel organogenesis and abscission.
Key Laboratory of Herbage & Endemic Crop Biotechnology, Ministry of Education, School of Life Science, Inner Mongolia University, Hohhot, 010021, China.; Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, 401331, Chongqing, China.; School of Biology and Basic Medical Sciences, Soochow University, Suzhou, China.; Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, 401331, Chongqing, China. zhengguoli@cqu.edu.cn.; Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, 401331, Chongqing, China. zhengguoli@cqu.edu.cn.; Key Laboratory of Herbage & Endemic Crop Biotechnology, Ministry of Education, School of Life Science, Inner Mongolia University, Hohhot, 010021, China. nmhadawu77@imu.edu.cn.
Abscission, a cell separation process, is an important trait that influences grain and fruit yield. We previously reported that BEL1-LIKE HOMEODOMAIN 4 (SlBL4) is involved in chloroplast development and cell wall metabolism in tomato fruit. In the present study, we showed that silencing SlBL4 resulted in the enlargement and pre-abscission of the tomato (Solanum lycopersicum cv. Micro-TOM) fruit pedicel. The anatomic analysis showed the presence of more epidermal cell layers and no obvious abscission zone (AZ) in the SlBL4 RNAi lines compared with the wild-type plants. RNA-seq analysis indicated that the regulation of abscission by SlBL4 was associated with the altered abundance of genes related to key meristems, auxin transporters, signaling components, and cell wall metabolism. Furthermore, SlBL4 positively affected the auxin concentration in the abscission zone. A dual-luciferase reporter assay revealed that SlBL4 activated the transcription of the JOINTLESS, OVATE, PIN1, and LAX3 genes. We reported a novel function of SlBL4, which plays key roles in fruit pedicel organogenesis and abscission in tomatoes.
PMID: 33790250
Hortic Res , IF:5.404 , 2021 Apr , V8 (1) : P74 doi: 10.1038/s41438-021-00509-y
Molecular and physiological characterization of the effects of auxin-enriched rootstock on grafting.
Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT, 06269, USA.; College of Horticulture, China Agricultural University, Beijing, 100193, PR China.; Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, 210014, PR China.; National Engineering Laboratory for Tree Breeding, College of Life Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083, PR China.; Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT, 06269, USA. liwei0522898@163.com.; College of Horticulture, China Agricultural University, Beijing, 100193, PR China. liwei0522898@163.com.; Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT, 06269, USA. yi.li@uconn.edu.
Grafting is a highly useful technique, and its success largely depends on graft union formation. In this study, we found that root-specific expression of the auxin biosynthetic gene iaaM in tobacco, when used as rootstock, resulted in more rapid callus formation and faster graft healing. However, overexpression of the auxin-inactivating iaaL gene in rootstocks delayed graft healing. We observed increased endogenous auxin levels and auxin-responsive DR5::GUS expression in scions of WT/iaaM grafts compared with those found in WT/WT grafts, which suggested that auxin is transported upward from rootstock to scion tissues. A transcriptome analysis showed that auxin enhanced graft union formation through increases in the expression of genes involved in graft healing in both rootstock and scion tissues. We also observed that the ethylene biosynthetic gene ACS1 and the ethylene-responsive gene ERF5 were upregulated in both scions and rootstocks of the WT/iaaM grafts. Furthermore, exogenous applications of the ethylene precursor ACC to the junction of WT/WT grafts promoted graft union formation, whereas application of the ethylene biosynthesis inhibitor AVG delayed graft healing in WT/WT grafts, and the observed delay was less pronounced in the WT/iaaM grafts. These results demonstrated that elevated auxin levels in the iaaM rootstock in combination with the increased auxin levels in scions caused by upward transport/diffusion enhanced graft union formation and that ethylene was partially responsible for the effects of auxin on grafting. Our findings showed that grafting success can be enhanced by increasing the auxin levels in rootstocks using transgenic or gene-editing techniques.
PMID: 33790234
Environ Microbiol , IF:4.933 , 2021 Apr , V23 (4) : P1876-1888 doi: 10.1111/1462-2920.15242
Serendipita bescii promotes winter wheat growth and modulates the host root transcriptome under phosphorus and nitrogen starvation.
Noble Research Institute, LLC, Ardmore, OK, 73401, USA.
Serendipita vermifera ssp. bescii, hereafter referred to as S. bescii, is a root-associated fungus that promotes plant growth in both its native switchgrass host and a variety of monocots and dicots. Winter wheat (Triticum aestivum L.), a dual-purpose crop, used for both forage and grain production, significantly contributes to the agricultural economies of the Southern Great Plains, USA. In this study, we investigated the influence of S. bescii on growth and transcriptome regulation of nitrogen (N) and phosphorus (P) metabolism in winter wheat. Serendipita bescii significantly improved lateral root growth and forage biomass under a limited N or P regime. Further, S. bescii activated sets of host genes regulating N and P starvation responses. These genes include, root-specific auxin transport, strigolactone and gibberellin biosynthesis, degradation of phospholipids and biosynthesis of glycerolipid, downregulation of ammonium transport and nitrate assimilation, restriction of protein degradation by autophagy and subsequent N remobilization. All these genes are hypothesized to regulate acquisition, assimilation and remobilization of N and P. Based on transcriptional level gene regulation and physiological responses to N or P limitation, we suggest S. bescii plays a critical role in modulating stress imposed by limitation of these two critical nutrients in winter wheat.
PMID: 32959463
Ecotoxicol Environ Saf , IF:4.872 , 2021 Apr , V216 : P112168 doi: 10.1016/j.ecoenv.2021.112168
Carbon dots inhibit root growth by disrupting auxin biosynthesis and transport in Arabidopsis.
College of Life Science, Shanxi Normal University, Linfen 041004, People's Republic of China; Higher Education Key Laboratory of Plant Molecular and Environmental Stress Response, Shanxi Normal University, Linfen 041004, Shanxi Province, People's Republic of China.; College of Life Science, Shanxi Normal University, Linfen 041004, People's Republic of China.; College of Life Science, Shanxi Normal University, Linfen 041004, People's Republic of China; Higher Education Key Laboratory of Plant Molecular and Environmental Stress Response, Shanxi Normal University, Linfen 041004, Shanxi Province, People's Republic of China. Electronic address: hhwrsl@163.com.
Carbon dots (CDs) possess considerable potentials in fields like biomarker and cell imaging due to its good fluorescence properties. Nevertheless, the molecular mechanism concerning influences of CDs on plant growth still remains unknown. In this study, the subcellular localization of CDs in Arabidopsis and the molecular mechanism of CDs toxicity to plants were investigated. Results demonstrate that CDs tend to accumulate in meristematic nucleus of root tips. CDs can inhibit growth of meristem zone of primary root (PR) of Arabidopsis seedlings significantly. The transcription level of auxin biosynthesis related genes decreases and the abundance of auxin efflux carriers PIN1 and PIN2 declines after 40 mg/L CDs treatment, thus lowering the auxin level in root tips. Moreover, CDs weaken activity of cell division in meristem zone by disturbing expressions of DNA damage repair genes and cell cycle regulation genes, thus enabling to inhibit growth of the meristem zone. To sum up, CDs inhibit growth of Arabidopsis seedlings through above pathways. These results provide useful information to elaborate potential toxicity mechanism of CDs on terrestrial plants.
PMID: 33819781
Ecotoxicol Environ Saf , IF:4.872 , 2021 Apr , V212 : P112002 doi: 10.1016/j.ecoenv.2021.112002
Cadmium stress suppresses the tillering of perennial ryegrass and is associated with the transcriptional regulation of genes controlling axillary bud outgrowth.
College of Pratacultural Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China.; Gansu Provincial Key Lab of Aridland Crop Science / Gansu Key Lab of Crop Improvement and Germplasm Enhancement, Lanzhou 730070, China.; College of Pratacultural Science, Gansu Agricultural University, Lanzhou, Gansu 730070, China. Electronic address: mahl@gsau.edu.cn.
Perennial ryegrass (Lolium perenne L.), a grass species with superior tillering capacity, plays a potential role in the phytoremediation of cadmium (Cd)-contaminated soils. Tiller production is inhibited in response to serious Cd stress. However, the regulatory mechanism of Cd stress-induced inhibition of tiller development is not well documented. To address this issue, we investigated the phenotype, the expression levels of genes involved in axillary bud initiation and bud outgrowth, and endogenous hormone biosynthesis and signaling pathways in seedlings of perennial ryegrass under Cd stress. The results showed that the number of tillers and axillary buds in the Cd-treated seedlings decreased by 67% and 21%, respectively. The suppression of tiller production in the Cd-treated seedlings was more closely associated with the inhibition of axillary bud outgrowth than with bud initiation. Cd stress upregulated the expression level of genes related to axillary bud dormancy and downregulated bud activity genes. Additionally, genes involved in strigolactone biosynthesis and signaling, auxin transport and signaling, and cytokinin degradation were upregulated in Cd-treated seedlings, and cytokinin biosynthesis gene expression were decreased by Cd stress. The content of zeatin in the Cd-treated pants was significantly reduced by 69~85% compared to the control plants. The content of indole-3-acetic acid (IAA) remains constant under Cd stress. Overall, Cd stress induced axillary bud dormancy and subsequently inhibited axillary bud outgrowth. The decrease of zeatin content and upregulation of genes involved in strigolactone signaling and bud dormancy might be responsible for the inhibition of axillary bud outgrowth.
PMID: 33529920
Biotechnol Biofuels , IF:4.815 , 2021 Apr , V14 (1) : P99 doi: 10.1186/s13068-021-01932-y
Molecular mechanism underlying the effect of maleic hydrazide treatment on starch accumulation in S. polyrrhiza 7498 fronds.
College of Life Science, Nankai University, Weijin Road 94, Tianjin, 300071, China.; School of Chinese Material Medica, Tianjin University of Traditional Chinese Medicine, Poyang Lake Road 10, Tianjin, 301617, China.; College of Life Science, Nankai University, Weijin Road 94, Tianjin, 300071, China. wangyong@nankai.edu.cn.
BACKGROUND: Duckweed is considered a promising feedstock for bioethanol production due to its high biomass and starch production. The starch content can be promoted by plant growth regulators after the vegetative reproduction being inhibited. Maleic hydrazide (MH) has been reported to inhibit plant growth, meantime to increase biomass and starch content in some plants. However, the molecular explanation on the mechanism of MH action is still unclear. RESULTS: To know the effect and action mode of MH on the growth and starch accumulation in Spirodela polyrrhiza 7498, the plants were treated with different concentrations of MH. Our results showed a substantial inhibition of the growth in both fronds and roots, and increase in starch contents of plants after MH treatment. And with 75 microg/mL MH treatment and on the 8th day of the experiment, starch content was the highest, about 40 mg/g fresh weight, which is about 20-fold higher than the control. The I2-KI staining and TEM results confirmed that 75 microg/mL MH-treated fronds possessed more starch and big starch granules than that of the control. No significant difference for both in the photosynthetic pigment content and the chlorophyll fluorescence parameters of PII was found. Differentially expressed transcripts were analyzed in S. polyrrhiza 7498 after 75 microg/mL MH treatment. The results showed that the expression of some genes related to auxin response reaction was down-regulated; while, expression of some genes involved in carbon fixation, C4 pathway of photosynthesis, starch biosynthesis and ABA signal transduction pathway was up-regulated. CONCLUSION: The results provide novel insights into the underlying mechanisms of growth inhibition and starch accumulation by MH treatment, and provide a selective way for the improvement of starch production in duckweed.
PMID: 33874980
Front Plant Sci , IF:4.402 , 2021 , V12 : P659061 doi: 10.3389/fpls.2021.659061
Auxin Response Factor 2 (ARF2), ARF3, and ARF4 Mediate Both Lateral Root and Nitrogen Fixing Nodule Development in Medicago truncatula.
Instituto de Biotecnologia y Biologia Molecular, Departamento de Ciencias Biologicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Centro Cientifico y Tecnologico-La Plata, Consejo Nacional de Investigaciones Cientificas y Tecnicas, La Plata, Argentina.; Noble Research Institute LLC, Ardmore, OK, United States.; Laboratoire des Interactions Plantes-Microorganismes, INRAE, CNRS, Universite de Toulouse, Castanet-Tolosan, France.
Auxin Response Factors (ARFs) constitute a large family of transcription factors that mediate auxin-regulated developmental programs in plants. ARF2, ARF3, and ARF4 are post-transcriptionally regulated by the microRNA390 (miR390)/trans-acting small interference RNA 3 (TAS3) module through the action of TAS3-derived trans - acting small interfering RNAs (ta-siRNA). We have previously reported that constitutive activation of the miR390/TAS3 pathway promotes elongation of lateral roots but impairs nodule organogenesis and infection by rhizobia during the nitrogen-fixing symbiosis established between Medicago truncatula and its partner Sinorhizobium meliloti. However, the involvement of the targets of the miR390/TAS3 pathway, i.e., MtARF2, MtARF3, MtARF4a, and MtARF4b, in root development and establishment of the nitrogen-fixing symbiosis remained unexplored. Here, promoter:reporter fusions showed that expression of both MtARF3 and MtARF4a was associated with lateral root development; however, only the MtARF4a promoter was active in developing nodules. In addition, up-regulation of MtARF2, MtARF3, and MtARF4a/b in response to rhizobia depends on Nod Factor perception. We provide evidence that simultaneous knockdown of MtARF2, MtARF3, MtARF4a, and MtARF4b or mutation in MtARF4a impaired nodule formation, and reduced initiation and progression of infection events. Silencing of MtARF2, MtARF3, MtARF4a, and MtARF4b altered mRNA levels of the early nodulation gene nodulation signaling pathway 2 (MtNSP2). In addition, roots with reduced levels of MtARF2, MtARF3, MtARF4a, and MtARF4b, as well as arf4a mutant plants exhibited altered root architecture, causing a reduction in primary and lateral root length, but increasing lateral root density. Taken together, our results suggest that these ARF members are common key players of the morphogenetic programs that control root development and the formation of nitrogen-fixing nodules.
PMID: 33897748
Plant Cell Physiol , IF:4.062 , 2021 Apr doi: 10.1093/pcp/pcab051
Making the "Green Revolution" Truly Green: improving crop nitrogen use efficiency.
Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601, Japan.; Faculty of Food and Agricultural Sciences, Fukushima University, Fukushima 960-1248, Japan.
Traditional breeding for high-yielding crops has mainly relied on the widespread cultivation of gibberellin (GA)-deficient semi-dwarf varieties, as dwarfism increases lodging resistance and allows for high nitrogen use, resulting in high grain yield. Although the adoption of semi-dwarf varieties in rice and wheat breeding brought big success to the "Green Revolution" in the 20th century, it consequently increased the demand for nitrogen-based fertilizer, which causes severe threat to ecosystems and sustainable agriculture. In order to make the "Green Revolution" truly green, it is necessary to develop new varieties with high nitrogen-use efficiency (NUE). Under this demand, research on NUE, mainly for rice, has made great strides in the last decade. This mini-review focuses on three aspects of recent epoch-making findings on rice breeding for high NUE. The first one on "NUE genes related to GA signaling" shows how promising it is to improve NUE in semi-dwarf Green Revolution Varieties. The second aspect centers around the nitrate transporter1.1B, NRT1.1B; studies have revealed a nutrient signaling pathway through the discovery of the nitrate-NRT1.1B-SPX4-NLP3 cascade. The last one is based on the recent finding that the Teosinte branched1, Cycloidea, Proliferating cell factor (TCP)-domain protein 19 underlies the genomic basis of geographical adaptation to soil nitrogen; OsTCP19 regulates the expression of a key transacting factor, DLT/SMOS2, which participates in the signaling of four different phytohormones, GA, auxin, brassinosteroid and strigolactone. Collectively, these breakthrough findings represent a significant step towards breeding high NUE rice in the future.
PMID: 33836084
Appl Environ Microbiol , IF:4.016 , 2021 Apr , V87 (9) doi: 10.1128/AEM.02989-20
A Stringent-Response-Defective Bradyrhizobium diazoefficiens Strain Does Not Activate the Type 3 Secretion System, Elicits an Early Plant Defense Response, and Circumvents NH4NO3-Induced Inhibition of Nodulation.
IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina.; Center for Synthetic Microbiology (SYNMIKRO), Department of Biology, Philipps-Universitat Marburg, Marburg, Germany.; Fundacion Instituto Leloir, Instituto de Investigaciones Bioquimicas de Buenos Aires-CONICET, Buenos Aires, Argentina.; Centro de Biotecnologia Vegetal, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile.; Millennium Institute for Integrative Biology (iBio), Santiago, Chile.; IBBM, Facultad de Ciencias Exactas, CCT-La Plata CONICET, Universidad Nacional de La Plata, La Plata, Argentina lodeiro@biol.unlp.edu.ar.; Laboratorio de Genetica, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, La Plata, Argentina.
When subjected to nutritional stress, bacteria modify their amino acid metabolism and cell division activities by means of the stringent response, which is controlled by the Rsh protein in alphaproteobacteria. An important group of alphaproteobacteria are the rhizobia, which fix atmospheric N2 in symbiosis with legume plants. Although nutritional stress is common for rhizobia while infecting legume roots, the stringent response has scarcely been studied in this group of soil bacteria. In this report, we obtained a mutant with a kanamycin resistance insertion in the rsh gene of Bradyrhizobium diazoefficiens, the N2-fixing symbiont of soybean. This mutant was defective for type 3 secretion system induction, plant defense suppression at early root infection, and nodulation competition. Furthermore, the mutant produced smaller nodules, although with normal morphology, which led to lower plant biomass production. Soybean (Glycine max) genes GmRIC1 and GmRIC2, involved in autoregulation of nodulation, were upregulated in plants inoculated with the mutant under the N-free condition. In addition, when plants were inoculated in the presence of 10 mM NH4NO3, the mutant produced nodules containing bacteroids, and GmRIC1 and GmRIC2 were downregulated. The rsh mutant released more auxin to the culture supernatant than the wild type, which might in part explain its symbiotic behavior in the presence of combined N. These results indicate that the B. diazoefficiens stringent response integrates into the plant defense suppression and regulation of nodulation circuits in soybean, perhaps mediated by the type 3 secretion system.IMPORTANCE The symbiotic N2 fixation carried out between prokaryotic rhizobia and legume plants performs a substantial contribution to the N cycle in the biosphere. This symbiotic association is initiated when rhizobia infect and penetrate the root hairs, which is followed by the growth and development of root nodules, within which the infective rhizobia are established and protected. Thus, the nodule environment allows the expression and function of the enzyme complex that catalyzes N2 fixation. However, during early infection, the rhizobia find a harsh environment while penetrating the root hairs. To cope with this nuisance, the rhizobia mount a stress response known as the stringent response. In turn, the plant regulates nodulation in response to the presence of alternative sources of combined N in the surrounding medium. Control of these processes is crucial for a successful symbiosis, and here we show how the rhizobial stringent response may modulate plant defense suppression and the networks of regulation of nodulation.
PMID: 33608284
Ann Bot , IF:4.005 , 2021 Apr doi: 10.1093/aob/mcab052
Stomatal Development in the Context of Epidermal Tissues.
Howard Hughes Medical Institute and Department of Molecular Biosciences, The University of Texas at Austin, Austin TX, USA.; Institute of Transformative Biomolecules (WPI-ITbM), Nagoya University, Nagoya, Aichi, Japan.
BACKGROUND: Stomata are adjustable pores on the surface of plant shoots for efficient gas exchange and water control. The presence of stomata is essential for plant growth and survival, and the evolution of stomata is considered as a key developmental innovation of the land plants, allowing colonization on land from aquatic environments some 450 million years ago. In the past two decades, molecular genetic studies using the model plant Arabidopsis thaliana identified key genes and signalling modules that regulate stomatal development: master-regulatory transcription factors that orchestrate cell-state transitions and peptide-receptor signal transduction pathways, which, together, enforce proper patterning of stomata within the epidermis. Studies in diverse plant species, ranging from bryophytes to angiosperm grasses, have begun to unravel the conservation and uniqueness of the core modules in stomatal development. SCOPE: Here, I review the mechanisms of stomatal development in the context of epidermal tissue patterning. First, I introduce the core regulatory mechanisms of stomatal patterning and differentiation in the model species Arabidopsis thaliana. Subsequently, experimental evidence is presented supporting the idea that different cell types within the leaf epidermis, namely stomata, hydathodes pores, pavement cells, and trichomes, either share developmental origins or mutually influence each other's gene regulatory circuits during development. Emphasis is taken on extrinsic and intrinsic signals regulating the balance between stomata and pavement cells, specifically by controlling the fate of Stomatal-Lineage Ground Cells (SLGCs) to remain within the stomatal-cell lineage or differentiate into pavement cells. Finally, I discuss the influence of inter-tissue-layer communication between the epidermis and underlying mesophyll/vascular tissues on stomatal differentiation. Understanding the dynamic behaviors of stomatal precursor cells and their differentiation in the broader context of tissue and organ development may help design plants tailored for optimal growth and productivity in specific agricultural applications and a changing environment.
PMID: 33877316
Microbiol Res , IF:3.97 , 2021 Apr , V248 : P126767 doi: 10.1016/j.micres.2021.126767
Trichoderma asperellum xylanases promote growth and induce resistance in poplar.
School of Forestry, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, China.; College of Forestry, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China. Electronic address: jsdwangyi@126.com.; College of Forestry, Shenyang Agricultural University, Shenyang, 110866, China.; College of Forestry, Shenyang Agricultural University, Shenyang, 110866, China; School of Forestry, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, China; Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China.; College of Forestry, Shenyang Agricultural University, Shenyang, 110866, China; School of Forestry, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, China. Electronic address: LiuZH789@syau.edu.cn.
Xylanase secreted by Trichoderma asperellum ACCC30536 can stimulate the systemic resistance of host plants against pathogenic fungi. Following T. asperellum conidia co-culture with Populus davidiana x P. alba var. pyramidalis Louche (PdPap) seedlings, the expression of xylanases TasXyn29.4 and TasXyn24.2 in T. asperellum were upregulated, peaking at 12 h, by 106 (2(6.74)) and 10.1 (2(3.34))-fold compared with the control, respectively. However, the expression of TasXyn24.4 and TasXyn24.0 was not detected. When recombinant xylanases rTasXyn29.4 and rTasXyn24.2 were heterologously expressed in Pichia pastoris GS115, their activities reached 18.9 IU/mL and 20.4 IU/mL, respectively. In PdPap seedlings induced by rTasXyn29.4 and rTasXyn24.2, the auxin and jasmonic acid signaling pathways were activated to promote growth and enhance resistance against pathogens. PdPap seedlings treated with both xylanases showed increased methyl jasmonate contents at 12 hpi, reaching 122 % (127 mug/g) compared with the control. However, neither of the xylanases could induce the salicylic acid signaling pathway in PdPap seedlings. Meanwhile, both xylanases could enhance the antioxidant ability of PdPap seedlings by improving their catalase activity. Both xylanases significantly induced systemic resistance of PdPap seedlings against Alternaria alternata, Rhizoctonia solani, and Fusarium oxysporum. However, the xylanases could only be sensed by the roots of the PdPap seedlings, not the leaves. In summary, rTasXyn29.4 and rTasXyn24.2 from T. asperellum ACCC30536 promoted growth and induced systemic resistance of PdPap seedlings, which endowed the PdPap seedlings broad-spectrum resistance to phytopathogens.
PMID: 33873138
Microbiol Res , IF:3.97 , 2021 Apr , V248 : P126754 doi: 10.1016/j.micres.2021.126754
Antifungal potential against Sclerotinia sclerotiorum (Lib.) de Bary and plant growth promoting abilities of Bacillus isolates from canola (Brassica napus L.) roots.
Departamento de Genetica, Instituto de Biociencias, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Goncalves, 9500, Caixa Postal 15.053, 91501-970, Porto Alegre, RS, Brazil.; LABRESIS - Laboratorio de Pesquisa em Resistencia Bacteriana, Centro de Pesquisa Experimental, Hospital de Clinicas de Porto Alegre (HCPA), Rua Ramiro Barcelos 2350, Porto Alegre, RS, 90.035-903, Brazil.; Departamento de Genetica, Instituto de Biociencias, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Goncalves, 9500, Caixa Postal 15.053, 91501-970, Porto Alegre, RS, Brazil. Electronic address: luciane.passaglia@ufrgs.br.
Endophytic bacteria show important abilities in promoting plant growth and suppressing phytopathogens, being largely explored in agriculture as biofertilizers or biocontrol agents. Bacteria from canola roots were isolated and screened for different plant growth promotion (PGP) traits and biocontrol of Sclerotinia sclerotiorum. Thirty isolates belonging to Bacillus, Paenibacillus, Lysinibacillus, and Microbacterium genera were obtained. Several isolates produced auxin, siderophores, hydrolytic enzymes, fixed nitrogen and solubilized phosphate. Five isolates presented antifungal activity against S. sclerotiorum by the dual culture assay and four of them also inhibited fungal growth by volatile organic compounds production. All antagonistic isolates belonged to the Bacillus genus, and had their genomes sequenced for the search of biosynthetic gene clusters (BGC) related to antimicrobial metabolites. These isolates were identified as Bacillus safensis (3), Bacillus pumilus (1), and Bacillus megaterium (1), using the genomic metrics ANI and dDDH. Most strains showed several common BGCs, including bacteriocin, polyketide synthase (PKS), and non-ribosomal peptide synthetase (NRPS), related to pumilacidin, bacillibactin, bacilysin, and other antimicrobial compounds. Pumilacidin-related mass peaks were detected in acid precipitation extracts through MALDI-TOF analysis. The genomic features demonstrated the potential of these isolates in the suppression of plant pathogens; however, some aspects of plant-bacterial interactions remain to be elucidated.
PMID: 33848783
Plant Physiol Biochem , IF:3.72 , 2021 Apr , V163 : P139-153 doi: 10.1016/j.plaphy.2021.03.059
Mining the rhizosphere of halophytic rangeland plants for halotolerant bacteria to improve growth and yield of salinity-stressed wheat.
Central Office of Natural Resources & Watershed Management, Yazd, Iran.; Department of Environmental Sciences, Faculty of Natural Resources, Yazd University, Yazd, Iran. Electronic address: amoleh@yazd.ac.ir.; Department of Soil Sciences, Faculty of Natural Resources, Yazd University, Yazd, Iran.; Forest and Rangeland Division, Yazd Agricultural and Natural Resource Research and Education Center, Yazd, Iran.; Department of Soil Science, University of Tehran, Karaj, Iran. Electronic address: hassanetesami@ut.ac.ir.; Faculty of Mathematics, Department of Statistics, Yazd University, Yazd, Iran.
In this study, the effects of three halotolerant rhizobacterial isolates AL, HR, and SB, which are able to grow at a salinity level of 1600 mM NaCl, with multiple plant growth promoting (PGP) traits on some seed and forage quality attributes, and vegetative, reproductive, biochemical and physiological characteristics of wheat plant irrigated with saline water (0, 40, 80, and 160 mM NaCl) were investigated. The ability of halotolerant bacterial isolates to produce PGP traits was affected by salinity levels, depending upon the bacterial isolates. Salinity stress significantly affected the yield, quality, and growth of wheat by modifying the morpho-physiological and biochemical traits of the exposed plants. However, all three bacterial isolates, especially isolate AL, significantly improved the biochemical (an increase in K(+)/Na(+) ratio by 55%, plant P content by 50%, and plant Ca content by 31%), morphological (an increase in stem dry weight by 52%, root dry weight by 44%, spike dry weight by 34%, and grain dry weight by 43%), and physiological (an increase in leaf proline content by 50% and total phenol in leaf by 42%) attributes of wheat and aided the plant to tolerate salinity stress in contrast to un-inoculated plant. Plants inoculated with bacterial isolates showed significantly improved seed amylose by 36%, leaf crude protein by 30%, leaf metabolic energy by 37%, and leaf water-soluble sugar content by 34%. Among the measured PGP and plant attributes, bacterial auxin and plant K content were of key importance in increasing reproductive performance of wheat. The bacterial isolates AL, HR, and SB were identified as Bacillus safensis, B. pumilus, and Zhihengliuella halotolerans, respectively, based on 16 S rDNA sequence. The study reveals that application of halotolerant plant growth-promoting rhizobacteria isolated from halophytic rangeland plants can be a cost effective and ecological sustainable method to improve wheat productivity, especially the attributes related to seed and forage quality, under salinity stress conditions.
PMID: 33845330
Plant Physiol Biochem , IF:3.72 , 2021 Apr , V161 : P131-142 doi: 10.1016/j.plaphy.2021.01.046
Calcium lignosulfonate improves proliferation of recalcitrant indica rice callus via modulation of auxin biosynthesis and enhancement of nutrient absorption.
Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. Electronic address: wanmuhamadasrul@gmail.com.; Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. Electronic address: ngaipaing@upm.edu.my.; Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. Electronic address: klein9201@gmail.com.; Faculty of Applied Sciences, UCSI University, Kuala Lumpur, Malaysia. Electronic address: lohjy@ucsiuniversity.edu.my.; Biotechnology and Nanotechnology Research Centre, MARDI Headquarters, Persiaran MARDI-UPM, Serdang, Selangor, Malaysia. Electronic address: cywee@mardi.gov.my.; Malaysia Genome Institute (MGI) National Institute of Biotechnology Malaysia (NIBM), Kajang, Selangor, Malaysia. Electronic address: azneyzuhaily@nibm.my.; Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia. Electronic address: janna@upm.edu.my.; Health Sciences Division, Abu Dhabi Women's College, Higher Colleges of Technology, Abu Dhabi, United Arab Emirates. Electronic address: lkoksong@hct.ac.ae.
Lignosulfonate (LS) is a commonly used to promote plant growth. However, the underlying growth promoting responses of LS in plant remain unknown. Therefore, this study was undertaken to elucidate the underlying growth promoting mechanisms of LS, specifically calcium lignosulfonate (CaLS). Addition of 100 mg/L CaLS in phytohormone-free media enhanced recalcitrant indica rice cv. MR219 callus proliferation rate and adventitious root formation. Both, auxin related genes (OsNIT1, OsTAA1 and OsYUC1) and tryptophan biosynthesis proteins were upregulated in CaLS-treated calli which corroborated with increased of endogenous auxin content. Moreover, increment of OsWOX11 gene on CaLS-treated calli implying that the raised of endogenous auxin was utilized as a cue to enhance adventitious root development. Besides, CaLS-treated calli showed higher nutrient ions content with major increment in calcium and potassium ions. Consistently, increased of potassium protein kinases genes (OsAKT1, OsHAK5, OsCBL, OsCIPK23 and OsCamk1) were also recorded. In CaLS treated calli, the significant increase of calcium ion was observed starting from week one while potassium ion only recorded significant increase on week two onwards, suggesting that increment of potassium ion might be dependent on the calcium ion content in the plant cell. Additionally, reduced callus blackening was also coherent with downregulation of ROS scavenging protein and reduced H2O2 content in CaLS-treated calli suggesting the role of CaLS in mediating cellular homeostasis via prevention of oxidative burst in the cell. Taken together, CaLS successfully improved MR219 callus proliferation and root formation by increasing endogenous auxin synthesis, enhancing nutrients uptake and regulating cellular homeostasis.
PMID: 33581621
Tree Physiol , IF:3.655 , 2021 Apr , V41 (4) : P529-543 doi: 10.1093/treephys/tpz101
Changes in phytohormone content and associated gene expression throughout the stages of pear (Pyrus pyrifolia Nakai) dormancy.
Institute of Fruit Tree and Tea Science, NARO, 2-1 Fujimoto, Tsukuba, Ibaraki 305-8605, Japan.; Department of Plant Science, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.; Graduate School of Horticulture, Chiba University, Matsudo, Chiba 271-8510, Japan.; Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zhejiang University, Hangzhou, Zhejiang 310058, China.
To elucidate the role of phytohormones during bud dormancy progression in the Japanese pear (Pyrus pyrifolia Nakai), we investigated changes in phytohormone levels of indole acetic acid (IAA), gibberellic acid (GA), abscisic acid (ABA) and trans-zeatin (tZ). Using ultra-performance liquid chromatography/mass spectrometry/mass spectrometry, we monitored phytohormone levels in the buds of field-grown and potted trees that were artificially heated to modify the timing of dormancy and flowering (spring flush) progression. We also analyzed the expression of GA- and ABA-metabolic genes during dormancy. Indole acetic acid and tZ levels were low during dormancy and increased toward the flowering stage. Gibberellic acid levels were maintained at relatively high concentrations during the dormancy induction stage, then decreased before slightly increasing prior to flowering. The low GA concentration in potted trees compared with field-grown trees indicated that GA functions in regulating tree vigor. Abscisic acid levels increased from the dormancy induction stage, peaked near endodormancy release and steadily decreased before increasing again before the flowering stage. The ABA peak levels did not always coincide with endodormancy release, but peak height correlated with flowering uniformity, suggesting that a decline in ABA concentration was not necessary for resumption of growth but the abundance of ABA might be associated with dormancy depth. From monitoring the expression of genes related to GA and ABA metabolism, we inferred that phytohormone metabolism changed significantly during dormancy, even though the levels of bioactive molecules were consistently low. Phytohormones regulate dormancy progression not only upon the reception of internal signals but also upon sensing ambient conditions.
PMID: 31595966
BMC Plant Biol , IF:3.497 , 2021 Apr , V21 (1) : P173 doi: 10.1186/s12870-021-02940-8
Cross-talk between transcriptome, phytohormone and HD-ZIP gene family analysis illuminates the molecular mechanism underlying fruitlet abscission in sweet cherry (Prunus avium L).
Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), Institute of Agro-bioengineering/ College of Life Sciences, Guizhou University, Guizhou Province, 550025, Guiyang, China.; Key laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), Institute of Agro-bioengineering/ College of Life Sciences, Guizhou University, Guizhou Province, 550025, Guiyang, China. xpwensc@hotmail.com.
BACKGROUND: The shedding of premature sweet cherry (Prunus avium L) fruitlet has significantly impacted production, which in turn has a consequential effect on economic benefits. RESULT: To better understand the molecular mechanism of sweet cherry fruitlet abscission, pollen viability and structure had been observed from the pollination trees. Subsequently, the morphological characters of the shedding fruitlet, the plant hormone titers of dropping carpopodium, the transcriptome of the abscising carpopodium, as well as the HD-ZIP gene family were investigated. These findings showed that the pollens giving rise to heavy fruitlet abscission were malformed in structure, and their viability was lower than the average level. The abscising fruitlet and carpopodium were characterized in red color, and embryos of abscising fruitlet were aborted, which was highly ascribed to the low pollen viability and malformation. Transcriptome analysis showed 6462 were significantly differentially expressed, of which 2456 genes were up-regulated and 4006 down-regulated in the abscising carpopodium. Among these genes, the auxin biosynthesis and signal transduction genes (alpha-Trp, AUX1), were down-regulated, while the 1-aminocyclopropane-1-carboxylate oxidase gene (ACO) affected in ethylene biosynthesis, was up-regulated in abscising carpopodium. About genes related to cell wall remodeling (CEL, PAL, PG EXP, XTH), were up-regulated in carpopodium abscission, which reflecting the key roles in regulating the abscission process. The results of transcriptome analysis considerably conformed with those of proteome analysis as documented previously. In comparison with those of the retention fruitlet, the auxin contents in abscising carpopodium were significantly low, which presumably increased the ethylene sensitivity of the abscission zone, conversely, the abscisic acid (ABA) accumulation was considerably higher in abscising carpopodium. Furthermore, the ratio of (TZ + IAA + GA3) / ABA also obviously lower in abscising carpopodium. Besides, the HD-ZIP gene family analysis showed that PavHB16 and PavHB18 were up-regulated in abscising organs. CONCLUSION: Our findings combine morphology, cytology and transcriptional regulation to reveal the molecular mechanism of sweet cherry fruitlet abscission. It provides a new perspective for further study of plant organ shedding.
PMID: 33838661
BMC Plant Biol , IF:3.497 , 2021 Apr , V21 (1) : P166 doi: 10.1186/s12870-021-02944-4
Auxin regulated metabolic changes underlying sepal retention and development after pollination in spinach.
College of Agriculture, FAFU and UIUC-SIB Joint Center for Genomics and Biotechnology, National Sugarcane Engineering Technology Research Center, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.; Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. rayming@illinois.edu.
BACKGROUND: Pollination accelerate sepal development that enhances plant fitness by protecting seeds in female spinach. This response requires pollination signals that result in the remodeling within the sepal cells for retention and development, but the regulatory mechanism for this response is still unclear. To investigate the early pollination-induced metabolic changes in sepal, we utilize the high-throughput RNA-seq approach. RESULTS: Spinach variety 'Cornel 9' was used for differentially expressed gene analysis followed by experiments of auxin analog and auxin inhibitor treatments. We first compared the candidate transcripts expressed differentially at different time points (12H, 48H, and 96H) after pollination and detected significant difference in Trp-dependent auxin biosynthesis and auxin modulation and transduction process. Furthermore, several auxin regulatory pathways i.e. cell division, cell wall expansion, and biogenesis were activated from pollination to early developmental symptoms in sepals following pollination. To further confirm the role auxin genes play in the sepal development, auxin analog (2, 4-D; IAA) and auxin transport inhibitor (NPA) with different concentrations gradient were sprayed to the spinach unpollinated and pollinated flowers, respectively. NPA treatment resulted in auxin transport weakening that led to inhibition of sepal development at concentration 0.1 and 1 mM after pollination. 2, 4-D and IAA treatment to unpollinated flowers resulted in sepal development at lower concentration but wilting at higher concentration. CONCLUSION: We hypothesized that sepal retention and development might have associated with auxin homeostasis that regulates the sepal size by modulating associated pathways. These findings advanced the understanding of this unusual phenomenon of sepal growth instead of abscission after pollination in spinach.
PMID: 33823793
Plant Mol Biol , IF:3.302 , 2021 Apr doi: 10.1007/s11103-021-01143-x
A coumarin exudation pathway mitigates arbuscular mycorrhizal incompatibility in Arabidopsis thaliana.
Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, the Netherlands. marco.rebecacosme@uclouvain.be.; Mycology, Applied Microbiology, Earth and Life Institute, Universite Catholique de Louvain, Croix du sud 2, bte L7.05.06, 1348, Louvain-la-Neuve, Belgium. marco.rebecacosme@uclouvain.be.; Plant-Microbe Interactions, Department of Biology, Science4Life, Utrecht University, PO Box 800.56, 3508 TB, Utrecht, the Netherlands.; Mycology, Applied Microbiology, Earth and Life Institute, Universite Catholique de Louvain, Croix du sud 2, bte L7.05.06, 1348, Louvain-la-Neuve, Belgium.; Plant-Soil Interactions, Department of Agroecology and Environment, Agroscope Reckenholz, Reckenholzstrasse 191, 8046, Zurich, Switzerland.; Department of Plant and Microbial Biology, University of Zurich, 8057, Zurich, Switzerland.
KEY MESSAGE: Overexpression of genes involved in coumarin production and secretion can mitigate mycorrhizal incompatibility in nonhost Arabidopsis plants. The coumarin scopoletin, in particular, stimulates pre-penetration development and metabolism in mycorrhizal fungi. Although most plants can benefit from mutualistic associations with arbuscular mycorrhizal (AM) fungi, nonhost plant species such as the model Arabidopsis thaliana have acquired incompatibility. The transcriptional response of Arabidopsis to colonization by host-supported AM fungi switches from initial AM recognition to defense activation and plant growth antagonism. However, detailed functional information on incompatibility in nonhost-AM fungus interactions is largely missing. We studied interactions between host-sustained AM fungal networks of Rhizophagus irregularis and 18 Arabidopsis genotypes affected in nonhost penetration resistance, coumarin production and secretion, and defense (salicylic acid, jasmonic acid, and ethylene) and growth hormones (auxin, brassinosteroid, cytokinin, and gibberellin). We demonstrated that root-secreted coumarins can mitigate incompatibility by stimulating fungal metabolism and promoting initial steps of AM colonization. Moreover, we provide evidence that major molecular defenses in Arabidopsis do not operate as primary mechanisms of AM incompatibility nor of growth antagonism. Our study reveals that, although incompatible, nonhost plants can harbor hidden tools that promote initial steps of AM colonization. Moreover, it uncovered the coumarin scopoletin as a novel signal in the pre-penetration dialogue, with possible implications for the chemical communication in plant-mycorrhizal fungi associations.
PMID: 33825084
J Plant Physiol , IF:3.013 , 2021 Apr , V261 : P153420 doi: 10.1016/j.jplph.2021.153420
Stem endophytes increase root development, photosynthesis, and survival of elm plantlets (Ulmus minor Mill.).
Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politecnica de Madrid, Madrid, 28040, Spain. Electronic address: clara.martinez.arias@upm.es.; Departamento de Sistemas y Recursos Naturales, ETSI Montes, Forestal y del Medio Natural, Universidad Politecnica de Madrid, Madrid, 28040, Spain.
Long-lived trees benefit from fungal symbiotic interactions in the adaptation to constantly changing environments. Previous studies revealed a core fungal endobiome in Ulmus minor which has been suggested to play a critical role in plant functioning. Here, we hypothesized that these core endophytes are involved in abiotic stress tolerance. To test this hypothesis, two core endophytes (Cystobasidiales and Chaetothyriales) were inoculated into in vitro U. minor plantlets, which were further subjected to drought. Given that elm genotypes resistant to Dutch elm disease (DED) tend to show higher abiotic stress tolerance than susceptible ones, we tested the endophyte effect on two DED-resistant and two DED-susceptible genotypes. Drought stress was moderate; endophyte presence attenuated stomata closure in response to drought in one genotype but this stress did not affect plant survival. In comparison, long-term in-vitro culture proved stressful to mock-inoculated plants, especially in DED-susceptible genotypes. Interestingly, no endophyte-inoculated plant died during the experiment, as compared to high mortality in mock-inoculated plants. In surviving plants, endophyte presence stimulated root and shoot growth, photosynthetic rates, antioxidant activity and molecular changes involving auxin-signaling. These changes and the observed endophyte stability in elm tissues throughout the experiment suggest endophytes are potential tools to improve survival and stress tolerance of DED-resistant elms in elm restoration programs.
PMID: 33906025
J Plant Physiol , IF:3.013 , 2021 Apr , V261 : P153415 doi: 10.1016/j.jplph.2021.153415
High ammonium inhibits root growth in Arabidopsis thaliana by promoting auxin conjugation rather than inhibiting auxin biosynthesis.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; State Key Laboratory of Crop Genetics and Germplasm Enhancement, Cytogenetics Institute, Nanjing Agricultural University/Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing, Jiangsu, 210095, China.; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; Institute of Food Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, 210014, China.; Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada; School of BioSciences, The University of Melbourne, Parkville, VIC, 3010, Australia.; National Centre for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100049, China.; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China. Electronic address: wmshi@issas.ac.cn.
Ammonium (NH4(+)) inhibits primary root (PR) growth in most plant species when present even at moderate concentrations. Previous studies have shown that transport of indole-3-acetic acid (IAA) is critical to maintaining root elongation under high-NH4(+) stress. However, the precise regulation of IAA homeostasis under high-NH4(+) stress (HAS) remains unclear. In this study, qRT-PCR, RNA-seq, free IAA and IAA conjugate and PR elongation measurements were conducted in genetic mutants to investigate the role of IAA biosynthesis and conjugation under HAS. Our data clearly show that HAS decreases free IAA in roots by increasing IAA inactivation but does not decrease IAA biosynthesis, and that the IAA-conjugating genes GH3.1, GH3.2, GH3.3, GH3.4, and GH3.6 function as the key genes in regulating high-NH4(+) sensitivity in the roots. Furthermore, the analysis of promoter::GUS staining in situ and genetic mutants reveals that HAS promotes IAA conjugation in the elongation zone (EZ), which may be responsible for the PR inhibition observed under HAS. This study provides potential new insight into the role of auxin in the improvement of tolerance to NH4(+).
PMID: 33894579
Biochem Biophys Res Commun , IF:2.985 , 2021 Apr , V549 : P21-26 doi: 10.1016/j.bbrc.2021.02.083
The Arabidopsis STE20/Hippo kinase SIK1 regulates polarity independently of PIN proteins.
Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, PR China. Electronic address: zhangppsmile@163.com.; Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, PR China. Electronic address: yuxiulian2009@yeah.net.; Tianjin Key Laboratory of Protein Sciences, Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, 94 Weijin Road, Tianjin, 300071, PR China. Electronic address: 1486973873@qq.com.; State Key Laboratory of Microbial Metabolism & Joint International Research Laboratory of Metabolic and Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, PR China. Electronic address: gongqingqiu@sjtu.edu.cn.
Polarity is a feature of life. In higher plants, non-autonomous polarity is largely directed by auxin, the morphogen that drives its own polarized flow, Polar Auxin Transport (PAT), to guide patterning events such as phyllotaxis and tropism. The plasma membrane-localized PIN-FORMED (PIN) auxin efflux carriers are rate-limiting factors in PAT. In yeasts and metazoans, the STE20 kinases are key players in cell polarity. We had previously characterized SIK1 as a STE20/Hippo orthologue in Arabidopsis and confirmed its function in mitotic exit and organ growth. Here we explore the possible link between SIK1, auxin, PIN, and polarity. Abnormal phyllotaxis and gravitropism were observed in sik1. sik1 was more sensitive to exogenous auxin in primary root elongation and lateral root emergence. RNA-Seq revealed reduced expression in auxin biosynthesis genes and induced expression of auxin flux carriers in sik1. However, normal tissue- and sub-cellular localization patterns of PIN1 and PIN2 were observed in sik1. The dark-induced vacuolar degradation of PIN2 also appeared normal in sik1. An additive phenotype was observed in the sik1 pin1 double mutant, indicating that SIK1 does not directly regulate PIN1. The polarity defects of sik1 are hence unlikely mediated by PINs and await future exploration.
PMID: 33652206
Protoplasma , IF:2.751 , 2021 Apr doi: 10.1007/s00709-021-01639-9
The auxin response factor (ARF) gene family in Oil palm (Elaeis guineensis Jacq.): Genome-wide identification and their expression profiling under abiotic stresses.
Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute, Chinese Academy of Tropical Agricultural Sciences, Wenchang, 571339, Hainan, People's Republic of China. jlf_0511@163.com.; Hainan Key Laboratory of Tropical Oil Crops Biology, Coconut Research Institute, Chinese Academy of Tropical Agricultural Sciences, Wenchang, 571339, Hainan, People's Republic of China.
Auxin response factors (ARFs) play vital role in controlling growth and developmental processes of plants via regulating the auxin signaling pathways. However, the identification and functional roles of ARFs in oil palm plants remain elusive. Here, we identified a total of 23 ARF (EgARF) genes in oil palm through a genome-wide identification approach. The EgARF gene structure analysis revealed the presence of intron-rich ARF gene family in genome of oil palm. Further analysis demonstrated the uneven distribution of 23EgARFs on 16 chromosomes of oil palm. Phylogenetic analysis clustered all the EgARFs into four groups. Twenty-one EgARFs contained BDD, ARF, and CTD domains, whereas EgARF5 and EgARF7 lacked the CTD domain. The evolution of ARF genes in oil palm genome has been expanded by segmental duplication events. The cis-acting regulatory elements of EgARF gene family were predominantly associated with the stress and hormone responses. Expression profiling data demonstrated the constitutive and tissue-specific expression of EgARF genes in various tissues of oil palm. Real-time PCR analysis of 19 EgARF genes expression levels under cold, drought, and salt stress conditions proved their prominent role under abiotic stress responses. Altogether, our study provides a basis for studying the molecular and functional roles of ARF genes in oil palm.
PMID: 33792785
J Econ Entomol , IF:1.938 , 2021 Apr , V114 (2) : P505-519 doi: 10.1093/jee/toab009
Buzz-Pollinated Crops: A Global Review and Meta-analysis of the Effects of Supplemental Bee Pollination in Tomato.
Department of Biological and Environmental Sciences, University of Stirling. Stirling, Scotland, UK.; School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK.
Buzz-pollinated plants require visitation from vibration producing bee species to elicit full pollen release. Several important food crops are buzz-pollinated including tomato, eggplant, kiwi, and blueberry. Although more than half of all bee species can buzz pollinate, the most commonly deployed supplemental pollinator, Apis mellifera L. (Hymenoptera: Apidae; honey bees), cannot produce vibrations to remove pollen. Here, we provide a list of buzz-pollinated food crops and discuss the extent to which they rely on pollination by vibration-producing bees. We then use the most commonly cultivated of these crops, the tomato, Solanum lycopersicum L. (Solanales: Solanaceae), as a case study to investigate the effect of different pollination treatments on aspects of fruit quality. Following a systematic review of the literature, we statistically analyzed 71 experiments from 24 studies across different geopolitical regions and conducted a meta-analysis on a subset of 21 of these experiments. Our results show that both supplemental pollination by buzz-pollinating bees and open pollination by assemblages of bees, which include buzz pollinators, significantly increase tomato fruit weight compared to a no-pollination control. In contrast, auxin treatment, artificial mechanical vibrations, or supplemental pollination by non-buzz-pollinating bees (including Apis spp.), do not significantly increase fruit weight. Finally, we compare strategies for providing bee pollination in tomato cultivation around the globe and highlight how using buzz-pollinating bees might improve tomato yield, particularly in some geographic regions. We conclude that employing native, wild buzz pollinators can deliver important economic benefits with reduced environmental risks and increased advantages for both developed and emerging economies.
PMID: 33615362
Evol Dev , IF:1.925 , 2021 Apr : Pe12376 doi: 10.1111/ede.12376
A fundamental developmental transition in Physcomitrium patens is regulated by evolutionarily conserved mechanisms.
Department of Plant Sciences, University of Oxford, Oxford, UK.
One of the most defining moments in history was the colonization of land by plants approximately 470 million years ago. The transition from water to land was accompanied by significant changes in the plant body plan, from those than resembled filamentous representatives of the charophytes, the sister group to land plants, to those that were morphologically complex and capable of colonizing harsher habitats. The moss Physcomitrium patens (also known as Physcomitrella patens) is an extant representative of the bryophytes, the earliest land plant lineage. The protonema of P. patens emerges from spores from a chloronemal initial cell, which can divide to self-renew to produce filaments of chloronemal cells. A chloronemal initial cell can differentiate into a caulonemal initial cell, which can divide and self-renew to produce filaments of caulonemal cells, which branch extensively and give rise to three-dimensional shoots. The process by which a chloronemal initial cell differentiates into a caulonemal initial cell is tightly regulated by auxin-induced remodeling of the actin cytoskeleton. Studies have revealed that the genetic mechanisms underpinning this transition also regulate tip growth and differentiation in diverse plant taxa. This review summarizes the known cellular and molecular mechanisms underpinning the chloronema to caulonema transition in P. patens.
PMID: 33822471
Curr Microbiol , IF:1.746 , 2021 Apr , V78 (4) : P1335-1343 doi: 10.1007/s00284-021-02408-w
Mitigation of Copper Stress in Maize (Zea mays) and Sunflower (Helianthus annuus) Plants by Copper-resistant Pseudomonas Strains.
Department of Soil Science, Faculty of Agriculture, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran. p.abbaszadeh@vru.ac.ir.; Department of Soil Science and Engineering, Agricultural College, University of Birjand, Birjand, Iran.; School of Agriculture and Environment and The UWA Institute of Agriculture, University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.; Department of Plant Protection, Ferdowsi University of Mashhad, Mashhad, Iran.; SoilsWest, UWA School of Agriculture and Environment, The University of Western Australia, Perth, WA, 6009, Australia.
Use of heavy metal (HM) resistant plant growth-promoting rhizobacteria (PGPR) is among the eco-friendly strategies to increase the resistance of crop plants against the HM stress. In this study, we investigated the effects of two copper (Cu)-resistant PGPR strains (Pseudomonas fluorescens P22 and Pseudomonas sp. Z6) on the growth and nutrition of maize (Zea mays) and sunflower (Helianthus annuus) plants grown in a Cu-contaminated soil under glasshouse conditions. Both PGPR strains significantly increased the plant vegetative parameters including shoot biomass, stem height and diameter, and chlorophyll (SPAD values) index in both crops. In both plants, the PGPR inoculations also significantly elevated the uptake of nutrients including potassium, phosphorus, calcium, magnesium (only by P. fluorescens P22), iron, zinc, manganese, and Cu. Magnitude of the nutritional effects varied between the PGPR strains, e.g., in sunflower, inoculation with P. fluorescens P22 and Pseudomonas sp. Z6 led to an increase in uptake of Zn by 42% and 114%, or Mn by 61% and 88%, respectively, in comparison with control plants. Improved performance of the inoculated plants can be attributed to the plant growth-promoting (e.g., production of auxin and siderophore, phosphate solubilization activities, etc.) and stress removal (e.g., production of ACC-deaminase to drop the ethylene level in stressed plants) properties of the PGPR strains, which were uncovered in our in vitro studies prior to the glasshouse experiment. Beside the plant growth-promoting traits of these PGPR strains, their high resistance to Cu toxicity seemed to be of particular importance for plant fitness improvement under Cu toxicity.
PMID: 33646377
Plant Signal Behav , IF:1.671 , 2021 Apr : P1911400 doi: 10.1080/15592324.2021.1911400
Barbara G. Pickard - Queen of Plant Electrophysiology.
IZMB, University of Bonn, Bonn, Germany.; Department of Agrifood Production and Environmental Sciences, University of Florence, Florence, Italy.; Biology Department, University of Washington, Seattle, WA, USA.
Barbara Gillespie Pickard (1936-2019) studied plant electrophysiology and mechanosensory biology for more than 50 y. Her first papers on the roles of auxin in plant tropisms were coauthored with Kenneth V. Thimann. Later, she studied plant electrophysiology. She made it clear that plant action potentials are not a peculiar feature of so-called sensitive plants, but that all plants exhibit these fast electric signals. Barbara Gillespie Pickard proposed a neuronal model for the spreading of electric signals induced by mechanical stimuli across plant tissues. In later years, she studied the stretch-activated plasma membrane channels of plants and formulated the plasma-membrane control center model. Barbara Pickard summarized all her findings in a new model of phyllotaxis involving waves of auxin fluxes and mechano-sensory signaling.
PMID: 33853497
Plant Signal Behav , IF:1.671 , 2021 Apr : P1906574 doi: 10.1080/15592324.2021.1906574
The potential roles of different metacaspases in maize defense response.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, Shandong, PR China.
Metacaspases (MCs), a class of cysteine-dependent proteases, act as important regulators in plant defense response. In maize genome, there are 11 ZmMCs which have been categorized into two types (type I and II) based on their structural differences. In this study, we investigated the different transcript patterns of 11 ZmMCs in maize defense response mediated by the nucleotide-binding, leucine-rich-repeat protein Rp1-D21. We further predicted that many cis-elements responsive to salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA) and auxin were identified in the promoter regions of ZmMCs, and several different transcription factors were predicted to bind to their promoters. We analyzed the localization of ZmMCs with previously identified quantitative trait loci (QTLs) in maize disease resistance, and found that all other ZmMCs, except for ZmMC6-8, are co-located with at least one QTL associated with disease resistance to southern leaf blight, northern leaf blight, gray leaf spot or Fusarium ear rot. Based on previous RNA-seq analysis, different ZmMCs display different transcript levels in response to Cochliobolous heterostrophus and Fusarium verticillioides. All the results imply that the members of ZmMCs might have differential functions to different maize diseases. This study lays the basis for further investigating the roles of ZmMCs in maize disease resistance.
PMID: 33843433
Plant Signal Behav , IF:1.671 , 2021 Apr , V16 (4) : P1885888 doi: 10.1080/15592324.2021.1885888
The role of auxin in nitrogen-modulated shoot branching.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture, Nanjing Agricultural University, Nanjing, China.; Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China.
Shoot branching is determined by axillary bud formation and outgrowth and remains one of the most variable determinants of yield in many crops. Plant nitrogen (N) acquired mainly in the forms of nitrate and ammonium from soil, dominates plant development, and high-yield crop production relies heavily on N fertilization. In this review, the regulation of axillary bud outgrowth by N availability and forms is summarized in plant species. The mechanisms of auxin function in this process have been well characterized and reviewed, while recent literature has highlighted that auxin export from a bud plays a critical role in N-modulating this process.
PMID: 33570443
Plant Signal Behav , IF:1.671 , 2021 Apr , V16 (4) : P1879532 doi: 10.1080/15592324.2021.1879532
Arabidopsis MYB28 and MYB29 transcription factors are involved in ammonium-mediated alterations of root-system architecture.
Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Bilbao, Spain.; Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
Ammonium (NH4(+)) is known to produce alterations in root-system architecture, notably, by inhibiting primary root elongation and stimulating lateral root branching. This stimulation is associated with higher auxin transport promoted by apoplast acidification. Recently, we showed that MYB28 and MYB29 transcription factors play a role in ammonium tolerance, since its double mutant (myb28myb29) is highly hypersensitive toward ammonium nutrition in relation to altered Fe homeostasis. In the present work, we observed that primary root elongation was lower in the mutant with respect to wild-type plants under ammonium nutrition. Moreover, ammonium-induced lateral root branching was impaired in myb28myb29 in a Fe-supply dependent manner. Further research is required to decipher the link between MYB28 and MYB29 functions and the signaling pathway leading to root-system architecture modification by NH4(+) supply.
PMID: 33538226