Autophagy , IF:16.016 , 2022 Sep : P1-18 doi: 10.1080/15548627.2022.2124501
Brassinosteroids modulate autophagy through phosphorylation of RAPTOR1B by the GSK3-like kinase BIN2 in Arabidopsis.
Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA.; Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA, USA.
Macroautophagy/autophagy is a conserved recycling process that maintains cellular homeostasis during environmental stress. Autophagy is negatively regulated by TOR (target of rapamycin), a nutrient-regulated protein kinase that in plants is activated by several phytohormones, leading to increased growth. However, the detailed molecular mechanisms by which TOR integrates autophagy and hormone signaling are poorly understood. Here, we show that TOR modulates brassinosteroid (BR)-regulated plant growth and stress-response pathways. Active TOR was required for full BR-mediated growth in Arabidopsis thaliana. Autophagy was constitutively up-regulated upon blocking BR biosynthesis or signaling, and down-regulated by increasing the activity of the BR pathway. BIN2 (brassinosteroid-insensitive 2) kinase, a GSK3-like kinase functioning as a negative regulator in BR signaling, directly phosphorylated RAPTOR1B (regulatory-associated protein of TOR 1B), a substrate-recruiting subunit in the TOR complex, at a conserved serine residue within a typical BIN2 phosphorylation motif. Mutation of RAPTOR1B serine 916 to alanine, to block phosphorylation by BIN2, repressed autophagy and increased phosphorylation of the TOR substrate ATG13a (autophagy-related protein 13a). By contrast, this mutation had only a limited effect on growth. We present a model in which RAPTOR1B is phosphorylated and inhibited by BIN2 when BRs are absent, activating the autophagy pathway. When BRs signal and inhibit BIN2, RAPTOR1B is thus less inhibited by BIN2 phosphorylation. This leads to increased TOR activity and ATG13a phosphorylation, and decreased autophagy activity. Our studies define a new mechanism by which coordination between BR and TOR signaling pathways helps to maintain the balance between plant growth and stress responses.
PMID: 36151786
Mol Plant , IF:13.164 , 2022 Oct , V15 (10) : P1543-1557 doi: 10.1016/j.molp.2022.08.008
The regeneration factors ERF114 and ERF115 regulate auxin-mediated lateral root development in response to mechanical cues.
Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent B-9052, Belgium; VIB Center for Plant Systems Biology, Ghent B-9052, Belgium.; Department of Plant Biology, Linnean Center for Plant Biology, Swedish University of Agricultural Sciences, Almas alle 5, 756 51 Uppsala, Sweden.; Department of Plant Biochemistry, Center for Plant Molecular Biology (ZMBP), University of Tubingen, 72076 Tubingen, Germany.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent B-9052, Belgium; VIB Center for Plant Systems Biology, Ghent B-9052, Belgium. Electronic address: lieven.deveylder@psb.vib-ugent.be.
Plants show an unparalleled regenerative capacity, allowing them to survive severe stress conditions, such as injury, herbivory attack, and harsh weather conditions. This potential not only replenishes tissues and restores damaged organs but can also give rise to whole plant bodies. Despite the intertwined nature of development and regeneration, common upstream cues and signaling mechanisms are largely unknown. Here, we demonstrate that in addition to being activators of regeneration, ETHYLENE RESPONSE FACTOR 114 (ERF114) and ERF115 govern developmental growth in the absence of wounding or injury. Increased ERF114 and ERF115 activity enhances auxin sensitivity, which is correlated with enhanced xylem maturation and lateral root formation, whereas their knockout results in a decrease in lateral roots. Moreover, we provide evidence that mechanical cues contribute to ERF114 and ERF115 expression in correlation with BZR1-mediated brassinosteroid signaling under both regenerative and developmental conditions. Antagonistically, cell wall integrity surveillance via mechanosensory FERONIA signaling suppresses their expression under both conditions. Taken together, our data suggest a molecular framework in which cell wall signals and mechanical strains regulate organ development and regenerative responses via ERF114- and ERF115-mediated auxin signaling.
PMID: 36030378
EMBO J , IF:11.598 , 2022 Oct , V41 (19) : Pe110682 doi: 10.15252/embj.2022110682
Salicylic acid-activated BIN2 phosphorylation of TGA3 promotes Arabidopsis PR gene expression and disease resistance.
Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, China.; School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, China.
The plant defense hormone, salicylic acid (SA), plays essential roles in immunity and systemic acquired resistance. Salicylic acid induced by the pathogen is perceived by the receptor nonexpressor of pathogenesis-related genes 1 (NPR1), which is recruited by TGA transcription factors to induce the expression of pathogenesis-related (PR) genes. However, the mechanism by which post-translational modifications affect TGA's transcriptional activity by salicylic acid signaling/pathogen infection is not well-established. Here, we report that the loss-of-function mutant of brassinosteroid insensitive2 (BIN2) and its homologs, bin2-3 bil1 bil2, causes impaired pathogen resistance and insensitivity to SA-induced PR gene expression, whereas the gain-of-function mutant, bin2-1, exhibited enhanced SA signaling and immunity against the pathogen. Our results demonstrate that salicylic acid activates BIN2 kinase, which in turn phosphorylates TGA3 at Ser33 to enhance TGA3 DNA binding ability and NPR1-TGA3 complex formation, leading to the activation of PR gene expression. These findings implicate BIN2 as a new component of salicylic acid signaling, functioning as a key node in balancing brassinosteroid-mediated plant growth and SA-induced immunity.
PMID: 35950443
Plant Cell , IF:11.277 , 2022 Oct , V34 (11) : P4516-4530 doi: 10.1093/plcell/koac245
The deubiquitinating enzymes UBP12 and UBP13 positively regulate recovery after carbon starvation by modulating BES1 stability in Arabidopsis thaliana.
Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Science, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China.; Department of Genetics, Development, and Cell Biology, Plant Sciences Institute, Iowa State University, Ames, Iowa 50011, USA.
BRI1-EMS-SUPPRESSOR1 (BES1), a core transcription factor in the brassinosteroid (BR) signaling pathway, primarily regulates plant growth and development by influencing BR-regulated gene expression. Several E3 ubiquitin (Ub) ligases regulate BES1 stability, but little is known about BES1 deubiquitination, which antagonizes E3 ligase-mediated ubiquitination to maintain BES1 homeostasis. Here, we report that two Arabidopsis thaliana deubiquitinating enzymes, Ub-SPECIFIC PROTEASE (UBP) 12 and UBP13, interact with BES1. UBP12 and UBP13 removed Ub from polyubiquitinated BES1 to stabilize both phosphorylated and dephosphorylated forms of BES1. A double mutant, ubp12-2w ubp13-3, lacking UBP12 and UBP13 function showed both BR-deficient and BR-insensitive phenotypes, whereas transgenic plants overexpressing UBP12 or UBP13 exhibited an increased BR response. Expression of UBP12 and UPB13 was induced during recovery after carbon starvation, which led to BES1 accumulation and quick recovery of stressed plants. Our work thus establishes a mechanism by which UBP12 and UBP13 regulate BES1 protein abundance to enhance BR-regulated growth during recovery after carbon starvation.
PMID: 35944221
Plant Cell , IF:11.277 , 2022 Sep , V34 (10) : P3501-3502 doi: 10.1093/plcell/koac222
Activation by inhibition: How redox signaling tunes brassinosteroid responses.
Assistant Features Editor, The Plant Cell, American Society of Plant Biologists, USA.; School of Biological Sciences, Institute of Molecular Plant Sciences, University of Edinburgh, UK.
PMID: 35916654
Plant Cell , IF:11.277 , 2022 Sep , V34 (10) : P3844-3859 doi: 10.1093/plcell/koac203
Adenosine monophosphate deaminase modulates BIN2 activity through hydrogen peroxide-induced oligomerization.
Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Ghent, Belgium.; Center for Plant Systems Biology, VIB, 9052 Ghent, Belgium.; Plant Developmental Biology, Wageningen University Research, 6708 PB Wageningen, The Netherlands.
The Arabidopsis thaliana GSK3-like kinase, BRASSINOSTEROID-INSENSITIVE2 (BIN2) is a key negative regulator of brassinosteroid (BR) signaling and a hub for crosstalk with other signaling pathways. However, the mechanisms controlling BIN2 activity are not well understood. Here we performed a forward genetic screen for resistance to the plant-specific GSK3 inhibitor bikinin and discovered that a mutation in the ADENOSINE MONOPHOSPHATE DEAMINASE (AMPD)/EMBRYONIC FACTOR1 (FAC1) gene reduces the sensitivity of Arabidopsis seedlings to both bikinin and BRs. Further analyses revealed that AMPD modulates BIN2 activity by regulating its oligomerization in a hydrogen peroxide (H2O2)-dependent manner. Exogenous H2O2 induced the formation of BIN2 oligomers with a decreased kinase activity and an increased sensitivity to bikinin. By contrast, AMPD activity inhibition reduced the cytosolic reactive oxygen species (ROS) levels and the amount of BIN2 oligomers, correlating with the decreased sensitivity of Arabidopsis plants to bikinin and BRs. Furthermore, we showed that BIN2 phosphorylates AMPD to possibly alter its function. Our results uncover the existence of an H2O2 homeostasis-mediated regulation loop between AMPD and BIN2 that fine-tunes the BIN2 kinase activity to control plant growth and development.
PMID: 35876813
Plant Cell , IF:11.277 , 2022 Sep , V34 (10) : P3754-3772 doi: 10.1093/plcell/koac196
Rice DWARF AND LOW-TILLERING and the homeodomain protein OSH15 interact to regulate internode elongation via orchestrating brassinosteroid signaling and metabolism.
National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China.; State Key Laboratory of Plant Genomics and Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.; Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, Hunan Agricultural University, Changsha 410128, China.; National Nanfan Research Institute, Chinese Academy of Agricultural Sciences, Sanya 572024, China.
Brassinosteroid (BR) phytohormones play crucial roles in regulating internode elongation in rice (Oryza sativa). However, the underlying mechanism remains largely unclear. The dwarf and low-tillering (dlt) mutant is a mild BR-signaling-defective mutant. Here, we identify two dlt enhancers that show more severe shortening of the lower internodes compared to the uppermost internode (IN1). Both mutants carry alleles of ORYZA SATIVA HOMEOBOX 15 (OSH15), the founding gene for dwarf6-type mutants, which have shortened lower internodes but not IN1. Consistent with the mutant phenotype, OSH15 expression is much stronger in lower internodes, particularly in IN2, than IN1. The osh15 single mutants have impaired BR sensitivity accompanied by enhanced BR synthesis in seedlings. DLT physically interacts with OSH15 to co-regulate many genes in seedlings and internodes. OSH15 targets and promotes the expression of the BR receptor gene BR INSENSITIVE1 (OsBRI1), and DLT facilitates this regulation in a dosage-dependent manner. In osh15, dlt, and osh15 dlt, BR levels are higher in seedlings and panicles, but unexpectedly lower in internodes compared with the wild-type. Taken together, our results suggest that DLT interacts with OSH15, which functions in the lower internodes, to modulate rice internode elongation via orchestrating BR signaling and metabolism.
PMID: 35789396
New Phytol , IF:10.151 , 2022 Oct doi: 10.1111/nph.18560
Molecular evidence for adaptive evolution of drought tolerance in wild cereals.
College of Agriculture and Biotechnology, Zhejiang University, Hangzhou, 310058, China.; Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.; Central Laboratory, Zhejiang Academy of Agricultural Sciences, Hangzhou, 310021, China.; Collaborative Innovation Centre for Grain Industry, College of Agriculture, Yangtze University, Jingzhou, 434025, China.; State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin'an, Hangzhou, 311300, PR China.; School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, China.; Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, UK.; Institute of Evolution, University of Haifa, Mount Carmel, 34988384, Haifa, Israel.; Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS, 7004, Australia.; School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia.; School of Science, Western Sydney University, Penrith, NSW, 2751, Australia.; Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia.
* The considerable drought tolerance of wild cereal crop progenitors has diminished during domestication in the pursuit of higher productivity. Regaining this trait in cereal crops is essential for global food security but requires novel genetic insight. * Here, we assessed the molecular evidence for natural variation of drought tolerance in wild barley (Hordeum spontaneum), wild emmer wheat (Triticum dicoccoides), and Brachypodium species collected from dry and moist habitats at Evolution Canyon, Israel (ECI). * We report that prevailing moist vs. dry conditions have differentially shaped the stomatal and photosynthetic traits of these wild cereals in their respective habitats. We present the genomic and transcriptomic evidence accounting for differences, including co-expression gene modules, correlated with physiological traits, and selective sweeps, driven by the xeric site conditions on the African Slope at ECI. Co-expression gene module 'circadian rhythm' was linked to significant drought-induced delay in flowering time in Brachypodium stacei genotypes. African Slope-specific differentially expressed genes are important in barley drought tolerance, verified by silencing Disease Related Nonspecific Lipid Transfer 1 (DRN1), Nonphotochemical Quenching 4 (NPQ4), and Brassinosteroid-Responsive Ring-H1 (BRH1). * Our results provide new genetic information for the breeding of resilient wheat and barley in a changing global climate with increasingly frequent drought events.
PMID: 36266957
New Phytol , IF:10.151 , 2022 Oct doi: 10.1111/nph.18557
Engineered AIM-based selective autophagy to degrade proteins and organelles in planta.
College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou, 510642, China.; Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China.; Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, 510631, China.; WIMI Biotechnology Co.,Ltd. Changzhou 213000, China.; Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou, 510642, China.
Protein-targeting technologies represent essential approaches in biological research. Protein knockdown tools developed recently in mammalian cells by exploiting natural degradation mechanisms allow for precise determination of protein function and discovery of degrader-type drugs. However, no method to directly target endogenous proteins for degradation is currently available in plants. Here, we describe a novel method for targeted protein clearance by engineering an autophagy receptor with a binder to provide target specificity and an ATG8-binding motif (AIM) to link the targets to nascent autophagosomes, thus harnessing the autophagy machinery for degradation. We demonstrate its specificity and broad potentials by degrading various fluorescence-tagged proteins, including cytosolic mCherry, the nucleus-localized bZIP transcription factor TGA5, and the plasma membrane-anchored brassinosteroid receptor BRI1, as well as fluorescence-coated peroxisomes, using a tobacco-based transient expression system. Stable expression of AIM-based autophagy receptors in Arabidopsis further confirms the feasibility of this approach in selective autophagy of endogenous proteins. With its wide substrate scope and its specificity, our concept of engineered AIM-based selective autophagy could provide a convenient and robust research tool for manipulating endogenous proteins in plants and may open an avenue toward degradation of cytoplasmic components other than proteins for plant research.
PMID: 36263708
Plant Physiol , IF:8.34 , 2022 Oct , V190 (3) : P1978-1996 doi: 10.1093/plphys/kiac354
DIACYLGLYCEROL KINASE 5 participates in flagellin-induced signaling in Arabidopsis.
Institute of Experimental Botany of the Czech Academy of Sciences, Rozvojova 263, 16502 Prague, Czech Republic.; Department of Experimental Plant Biology, Charles University, Vinicna 5, Prague 12844, Czech Republic.; Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Universite Paris-Sud, Universite Evry, Universite Paris-Saclay, Batiment 630, 91405 Orsay, France.; Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-Cite, Batiment 630, 91405 Orsay, France.; Laboratoire de Physiologie Cellulaire et Moleculaire des Plantes, Sorbonne Universite, F-75005 Paris, France.; CNRS Enzyme and Cell Engineering Laboratory, Universite de Technologie de Compiegne, Rue du Docteur Schweitzer, 60203 Compiegne, France.
Flagellin perception is a keystone of pattern-triggered immunity in plants. The recognition of this protein by a plasma membrane (PM) receptor complex is the beginning of a signaling cascade that includes protein phosphorylation and the production of reactive oxygen species (ROS). In both Arabidopsis (Arabidopsis thaliana) seedlings and suspension cells, we found that treatment with flg22, a peptide corresponding to the most conserved domain of bacterial flagellin, caused a rapid and transient decrease in the level of phosphatidylinositol (PI) 4,5-bisphosphate along with a parallel increase in phosphatidic acid (PA). In suspension cells, inhibitors of either phosphoinositide-dependent phospholipases C (PLC) or diacylglycerol kinases (DGKs) inhibited flg22-triggered PA production and the oxidative burst. In response to flg22, receptor-like kinase-deficient fls2, bak1, and bik1 mutants (FLAGELLIN SENSITIVE 2, BRASSINOSTEROID INSENSITIVE 1-associated kinase 1, and BOTRYTIS-INDUCED KINASE 1, respectively) produced less PA than wild-type (WT) plants, whereas this response did not differ in NADPH oxidase-deficient rbohD (RESPIRATORY BURST OXIDASE HOMOLOG D) plants. Among the DGK-deficient lines tested, the dgk5.1 mutant produced less PA and less ROS after flg22 treatment compared with WT seedlings. In response to flg22, dgk5.1 plants showed lower callose accumulation and impaired resistance to Pseudomonas syringae pv. tomato DC3000 hrcC-. Transcriptomics revealed that the basal expression of defense-related genes was altered in dgk5.1 seedlings compared with the WT. A GFP-DGK5 fusion protein localized to the PM, where RBOHD and PLC2 (proteins involved in plant immunity) are also located. The role of DGK5 and its enzymatic activity in flagellin signaling and fine-tuning of early immune responses in plant-microbe interactions is discussed.
PMID: 35900211
Plant Physiol , IF:8.34 , 2022 Sep , V190 (2) : P1457-1473 doi: 10.1093/plphys/kiac332
Class I TCP transcription factor AtTCP8 modulates key brassinosteroid-responsive genes.
Department of Biological Sciences, Butler University, Indianapolis, Indiana, USA.; Division of Plant Science and Technology, University of Missouri, Columbia, Missouri, USA.; Christopher S. Bond Life Sciences Center and Interdisciplinary Plant Group, University of Missouri, Columbia, Missouri, USA.; Department of Biology, Marian University, Indianapolis, Indiana, USA.
The plant-specific TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) transcription factor family is most closely associated with regulating plant developmental programs. Recently, TCPs were also shown to mediate host immune signaling, both as targets of pathogen virulence factors and as regulators of plant defense genes. However, comprehensive characterization of TCP gene targets is still lacking. Loss of function of the class I TCP gene AtTCP8 attenuates early immune signaling and, when combined with mutations in AtTCP14 and AtTCP15, additional layers of defense signaling in Arabidopsis (Arabidopsis thaliana). Here, we focus on TCP8, the most poorly characterized of the three to date. We used chromatin immunoprecipitation and RNA sequencing to identify TCP8-bound gene promoters and differentially regulated genes in the tcp8 mutant; these datasets were heavily enriched in signaling components for multiple phytohormone pathways, including brassinosteroids (BRs), auxin, and jasmonic acid. Using BR signaling as a representative example, we showed that TCP8 directly binds and activates the promoters of the key BR transcriptional regulatory genes BRASSINAZOLE-RESISTANT1 (BZR1) and BRASSINAZOLE-RESISTANT2 (BZR2/BES1). Furthermore, tcp8 mutant seedlings exhibited altered BR-responsive growth patterns and complementary reductions in BZR2 transcript levels, while TCP8 protein demonstrated BR-responsive changes in subnuclear localization and transcriptional activity. We conclude that one explanation for the substantial targeting of TCP8 alongside other TCP family members by pathogen effectors may lie in its role as a modulator of BR and other plant hormone signaling pathways.
PMID: 35866682
Plant Physiol , IF:8.34 , 2022 Sep , V190 (2) : P1182-1198 doi: 10.1093/plphys/kiac327
Brassinosteroid signaling restricts root lignification by antagonizing SHORT-ROOT function in Arabidopsis.
College of Life Science & College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou 350002, China.; Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaboration Innovation Center for Cell Signaling, Hebei Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, China.; Key Laboratory of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Jinan, China.
Cell wall lignification is a key step in forming functional endodermis and protoxylem (PX) in plant roots. Lignified casparian strips (CS) in endodermis and tracheary elements of PX are essential for selective absorption and transport of water and nutrients. Although multiple key regulators of CS and PX have been identified, the spatial information that drives the developmental shift to root lignification remains unknown. Here, we found that brassinosteroid (BR) signaling plays a key role in inhibiting root lignification in the root elongation zone. The inhibitory activity of BR signaling occurs partially through the direct binding of BRASSINAZOLE-RESISTANT 1 (BZR1) to SHORT-ROOT (SHR), repressing the SHR-mediated activation of downstream genes that are involved in root lignification. Upon entering the mature root zone, BR signaling declines rapidly, which releases SHR activity and initiates root lignification. Our results provide a mechanistic view of the developmental transition to cell wall lignification in Arabidopsis thaliana roots.
PMID: 35809074
Elife , IF:8.14 , 2022 Sep , V11 doi: 10.7554/eLife.73031
Computational modeling and quantitative physiology reveal central parameters for brassinosteroid-regulated early cell physiological processes linked to elongation growth of the Arabidopsis root.
Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany.; BioQuant, Heidelberg University, Heidelberg, Germany.; Center for Molecular Biology of Plants, University of Tubingen, Tubingen, Germany.; Department of Ecological and biological Science, Tuscia University, Viterbo, Italy.; Tasmanian Institute for Agriculture, University of Tasmania, Hobart, Australia.; International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China.
Brassinosteroids (BR) are key hormonal regulators of plant development. However, whereas the individual components of BR perception and signaling are well characterized experimentally, the question of how they can act and whether they are sufficient to carry out the critical function of cellular elongation remains open. Here, we combined computational modeling with quantitative cell physiology to understand the dynamics of the plasma membrane (PM)-localized BR response pathway during the initiation of cellular responses in the epidermis of the Arabidopsis root tip that are be linked to cell elongation. The model, consisting of ordinary differential equations, comprises the BR-induced hyperpolarization of the PM, the acidification of the apoplast and subsequent cell wall swelling. We demonstrate that the competence of the root epidermal cells for the BR response predominantly depends on the amount and activity of H(+)-ATPases in the PM. The model further predicts that an influx of cations is required to compensate for the shift of positive charges caused by the apoplastic acidification. A potassium channel was subsequently identified and experimentally characterized, fulfilling this function. Thus, we established the landscape of components and parameters for physiological processes potentially linked to cell elongation, a central process in plant development.
PMID: 36069528
Sci Total Environ , IF:7.963 , 2022 Sep , V838 (Pt 4) : P156503 doi: 10.1016/j.scitotenv.2022.156503
OsBR6ox, a member in the brassinosteroid synthetic pathway facilitates degradation of pesticides in rice through a specific DNA demethylation mechanism.
Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing 210095, China.; Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing 210095, China; Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China.; Syngenta Crop Protection AG, Rosentalstrasse 67, CH-4002 Basel, Switzerland.; Syngenta Ltd, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK.; Jiangsu Key Laboratory of Pesticide Science, College of Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: hongyang@njau.edu.cn.
This manuscript described a comprehensive study on a pesticide degradation factor OsBR6ox that promoted the degradation of pesticides atrazine (ATZ) and acetochlor (ACT) in rice tissues and grains through an epigenetic mechanism. OsBR6ox was transcriptionally induced under ATZ and ACT stress. Genetic disruption of OsBR6ox increased rice sensitivity and led to more accumulation of ATZ and ACT, whereas transgenic rice overexpressing OsBR6ox lines (OEs) showed opposite effects with improved growth and lower ATZ and ACT accumulation in various tissues, including grains. OsBR6ox-mediated detoxification of ATZ and ACT was associated with the increased abundance of brassinolide (one of the brassinosteroids, BRs), a plant growth regulator for stress responses. Some Phase I-II reaction protein genes for pesticide detoxification such as genes encoding laccase, O-methyltransferase and glycosyltransferases were transcriptionally upregulated in OE lines under ATZ and ACT stress. HPLC-Q-TOF-MS/MS analysis revealed an enhanced ATZ/ATC metabolism in OE plants, which removed 1.21-1.49 fold ATZ and 1.31-1.44 fold ACT from the growth medium but accumulated only 83.1-87.1 % (shoot) and 71.7-84.1 % (root) of ATZ and 69.4-83.4 % of ACT of the wild-type. Importantly, an ATZ-responsive demethylated region in the upstream of OsBR6ox was detected. Such an epigenetic modification marker was responsible for the increased OsBR6ox expression and consequent detoxification of ATZ/ACT in rice and environment. Overall, this work uncovered a new model showing that plants utilize two mechanisms to co-regulate the detoxification and metabolism of pesticides in rice and provided a new approach for building up cleaner crops and eliminating residual pesticides in environments.
PMID: 35688248
Plant Cell Environ , IF:7.228 , 2022 Sep doi: 10.1111/pce.14441
HOP1 and HOP2 are involved in salt tolerance by facilitating the brassinosteroid-related nucleo-cytoplasmic partitioning of the HSP90-BIN2 complex.
College of Life Science, Shandong Normal University, Jinan, China.
The co-chaperone heat shock protein (HSP)70-HSP90 organizing protein (HOP) is involved in plant thermotolerance. However, its function in plant salinity tolerance was not yet studied. We found that Arabidopsis HOP1 and HOP2 play critical roles in salt tolerance by affecting the nucleo-cytoplasmic partitioning of HSP90 and brassinosteroid-insensitive 2 (BIN2). A hop1/2 double mutant was hypersensitive to salt-stress. Interestingly, this sensitivity was remedied by exogenous brassinolide application, while the application of brassinazole impeded growth of both wild-type (WT) and hop1/2 plants under normal and salt stress conditions. This suggested that the insufficient brassinosteroid (BR) content was responsible for the salt-sensitivity of hop1/2. After WT was transferred to salt stress conditions, HOP1/2, BIN2 and HSP90 accumulated in the nucleus, brassinazole-resistant 1 (BZR1) was phosphorylated and accumulated in the cytoplasm, and BR content significantly increased. This initial response resulted in dephosphorylation of BZR1 and BR response. This dynamic regulation of BR content was impeded in salt-stressed hop1/2. Thus, we propose that HOP1 and HOP2 are involved in salt tolerance by affecting BR signalling.
PMID: 36123951
J Integr Plant Biol , IF:7.061 , 2022 Oct doi: 10.1111/jipb.13397
CKL2 mediates the crosstalk between abscisic acid and brassinosteroid signaling to promote swift growth recovery after stress in Arabidopsis.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China.; Key Laboratory of Plant Stress, Life Science College, Shandong Normal University, Jinan, 250014, China.
Plants must adapt to the constantly changing environment. Adverse environmental conditions trigger various defensive responses, including growth inhibition mediated by phytohormone abscisic acid (ABA). When the stress recedes, plants must transit rapidly from stress defense to growth recovery, but the underlying mechanisms by which plants switch promptly and accurately between stress resistance and growth are poorly understood. Here, using quantitative phosphoproteomics strategy, we discovered that early ABA signaling activates upstream components of brassinosteroid (BR) signaling through CASEIN KINASE 1-LIKE PROTEIN 2 (CKL2). Further investigations showed that CKL2 interacts with and phosphorylates BRASSINOSTEROID INSENSITIVE1 (BRI1), the main BR receptor, to maintain basal activity of the upstream of BR pathway in plants exposed to continuous stress conditions. When stress recedes, the elevated phosphorylation of BRI1 by CKL2 contributes to swift reactivation of BR signaling, which results in quick growth recovery. These results suggest that CKL2 plays a critical regulatory role in the rapid switch between growth and stress resistance. Our evidence expands the understanding of how plants modulate stress defense and growth by integrating ABA and BR signaling cascades. This article is protected by copyright. All rights reserved.
PMID: 36282494
J Integr Plant Biol , IF:7.061 , 2022 Sep doi: 10.1111/jipb.13356
Brassinosteroid signaling positively regulates abscisic acid biosynthesis in response to chilling stress in tomato.
Department of Horticulture, Zhejiang University, Hangzhou, 310058, China.; Hainan Institute, Zhejiang University, Sanya, 572025, China.; Key Laboratory of Horticultural Plants Growth, Development and Quality Improvement, Agricultural Ministry of China, Hangzhou, 310058, China.
Brassinosteroids (BRs) and abscisic acid (ABA) are essential regulators of plant growth and stress tolerance. Although the antagonistic interaction of BRs and ABA is proposed to ensure the balance between growth and defense in model plants, the crosstalk between BRs and ABA in response to chilling in tomato (Solanum lycopersicum), a warm-climate horticultural crop, is unclear. Here, we determined that overexpression of the BR biosynthesis gene DWARF (DWF) or the key BR signaling gene BRASSINAZOLE-RESISTANT1 (BZR1) increases ABA levels in response to chilling stress via positively regulating the expression of the ABA biosynthesis gene 9-CIS-EPOXYCAROTENOID DIOXYGENASE1 (NCED1). BR-induced chilling tolerance was mostly dependent on ABA biosynthesis. Chilling stress or high BR levels decreased the abundance of BRASSINOSTEROID-INSENSITIVE2 (BIN2), a negative regulator of BR signaling. Moreover, we observed that chilling stress increases BR levels and results in the accumulation of BZR1. BIN2 negatively regulated both the accumulation of BZR1 protein and chilling tolerance by suppressing ABA biosynthesis. Our results demonstrate that BR signaling positively regulates chilling tolerance via ABA biosynthesis in tomato. The study has implications in production of warm-climate crops in horticulture. This article is protected by copyright. All rights reserved.
PMID: 36053143
J Integr Plant Biol , IF:7.061 , 2022 Oct , V64 (10) : P1883-1900 doi: 10.1111/jipb.13333
Ribonuclease H-like gene SMALL GRAIN2 regulates grain size in rice through brassinosteroid signaling pathway.
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Nanjing National Field Scientific Observation and Research Station for Rice Germplasm, Nanjing Agricultural University, Nanjing, 210095, China.; National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
Grain size is a key agronomic trait that determines the yield in plants. Regulation of grain size by brassinosteroids (BRs) in rice has been widely reported. However, the relationship between the BR signaling pathway and grain size still requires further study. Here, we isolated a rice mutant, named small grain2 (sg2), which displayed smaller grain and a semi-dwarf phenotype. The decreased grain size was caused by repressed cell expansion in spikelet hulls of the sg2 mutant. Using map-based cloning combined with a MutMap approach, we cloned SG2, which encodes a plant-specific protein with a ribonuclease H-like domain. SG2 is a positive regulator downstream of GLYCOGEN SYNTHASE KINASE2 (GSK2) in response to BR signaling, and its mutation causes insensitivity to exogenous BR treatment. Genetical and biochemical analysis showed that GSK2 interacts with and phosphorylates SG2. We further found that BRs enhance the accumulation of SG2 in the nucleus, and subcellular distribution of SG2 is regulated by GSK2 kinase activity. In addition, Oryza sativa OVATE family protein 19 (OsOFP19), a negative regulator of grain shape, interacts with SG2 and plays an antagonistic role with SG2 in controlling gene expression and grain size. Our results indicated that SG2 is a new component of GSK2-related BR signaling response and regulates grain size by interacting with OsOFP19.
PMID: 35904032
J Exp Bot , IF:6.992 , 2022 Sep , V73 (16) : P5529-5542 doi: 10.1093/jxb/erac222
OsBSK2, a putative brassinosteroid-signalling kinase, positively controls grain size in rice.
State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Chengdu, Sichuan, China.; Rice Research Institute, Sichuan Agricultural University, Chengdu, Sichuan, China.
Grain size is an important trait that directly affects grain yield in rice; however, the genetic and molecular mechanisms regulating grain size remain unclear. In this study, we identified a mutant, grain length and grain weight 10 (glw10), which exhibited significantly reduced grain length and grain weight. Histological analysis demonstrated that GLW10 affects cell expansion, which regulates grain size. MutMap-based gene mapping and transgenic experiments demonstrated that GLW10 encodes a putative brassinosteroid (BR) signalling kinase, OsBSK2. OsBSK2 is a plasma membrane protein, and an N-myristoylation site is needed for both membrane localization and function. OsBSK2 directly interacts with the BR receptor kinase OsBRI1; however, genetic experiments have demonstrated that OsBSK2 may regulate grain size independent of the BR signalling pathway. OsBSK2 can form a homodimer or heterodimer with OsBSK3 and OsBSK4, and silencing OsBSK2, OsBSK3, and OsBSK4 reduce grain size. This indicates that OsBSKs seem to function as homodimers or heterodimers to positively regulate grain size in rice. OsBSK2/3/4 are all highly expressed in young panicles and spikelet hulls, suggesting that they control grain size. In summary, our results provide novel insights into the function of BSKs in rice, and identify novel targets for improving grain size during crop breeding.
PMID: 35595300
Plant J , IF:6.417 , 2022 Oct doi: 10.1111/tpj.15980
The Arabidopsis TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE (TTL) family members are involved in root system formation via their interaction with cytoskeleton and cell wall remodeling.
Department of Experimental Plant Biology, Faculty of Science, Charles University, Vinicna 5, 128 44, Prague 2, Czech Republic.; Departamento de Biologia Molecular de Plantas, Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico (UNAM), Av. Universidad, 2001, Cuernavaca, 62250, Morelos, Mexico.; Group of Reproductive Development and Apomixis, UGA Laboratorio Nacional de Genomica para la Biodiversidad, CINVESTAV Irapuato, Guanajuato, 36821, Mexico.
Lateral roots (LR) are essential components of the plant edaphic interface; contributing to water and nutrient uptake, biotic and abiotic interactions, stress survival, and plant anchorage. We have identified the TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE 3 (TTL3) gene as being related to LR emergence and later development. Loss of function of TTL3 leads to a reduced number of emerged LR due to delayed development of lateral root primordia (LRP). This trait is further enhanced in the triple mutant ttl1ttl3ttl4. TTL3 interacts with microtubules and endomembranes, and is known to participate in the brassinosteroid (BR) signaling pathway. Both ttl3 and ttl1ttl3ttl4 mutants are less sensitive to BR treatment in terms of LR formation and primary root growth. The ability of TTL3 to modulate biophysical properties of the cell wall was established under restrictive conditions of hyperosmotic stress and loss of root growth recovery, which was enhanced in ttl1ttl3ttl4. Timing and spatial distribution of TTL3 expression is consistent with its role in development of LRP before their emergence and subsequent growth of LR. TTL3 emerged as a component of the root system morphogenesis regulatory network.
PMID: 36270031
Plant J , IF:6.417 , 2022 Oct , V112 (2) : P493-517 doi: 10.1111/tpj.15961
Transcriptional responses to gibberellin in the maize tassel and control by DELLA domain proteins.
USDA, Agriculture Research Service, Plant Genetics Research Unit, Columbia, Missouri, 65211, USA.; Department of Biochemistry, Purdue University; West Lafayette, Indiana, 47907, USA.; Center for Plant Biology, Purdue University, West Lafayette, Indiana, 47907, USA.
The plant hormone gibberellin (GA) impacts plant growth and development differently depending on the developmental context. In the maize (Zea mays) tassel, application of GA alters floral development, resulting in the persistence of pistils. GA signaling is achieved by the GA-dependent turnover of DELLA domain transcription factors, encoded by dwarf8 (d8) and dwarf9 (d9) in maize. The D8-Mpl and D9-1 alleles disrupt GA signaling, resulting in short plants and normal tassel floret development in the presence of excess GA. However, D9-1 mutants are unable to block GA-induced pistil development. Gene expression in developing tassels of D8-Mpl and D9-1 mutants and their wild-type siblings was determined upon excess GA3 and mock treatments. Using GA-sensitive transcripts as reporters of GA signaling, we identified a weak loss of repression under mock conditions in both mutants, with the effect in D9-1 being greater. D9-1 was also less able to repress GA signaling in the presence of excess GA3 . We treated a diverse set of maize inbred lines with excess GA3 and measured the phenotypic consequences on multiple aspects of development (e.g., height and pistil persistence in tassel florets). Genotype affected all GA-regulated phenotypes but there was no correlation between any of the GA-affected phenotypes, indicating that the complexity of the relationship between GA and development extends beyond the two-gene epistasis previously demonstrated for GA and brassinosteroid biosynthetic mutants.
PMID: 36050832
Plant J , IF:6.417 , 2022 Oct , V112 (2) : P476-492 doi: 10.1111/tpj.15960
Bioenergy sorghum stem growth regulation: intercalary meristem localization, development, and gene regulatory network analysis.
Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, 77843-2128, USA.; ABQMR, Inc., 2301 Yale Blvd. SE, Suite C2, Albuquerque, New Mexico, 87106, USA.; Department of Plant Biology, University of Illinois, Champaign-Urbana, Illinois, 61801, USA.
Bioenergy sorghum is a highly productive drought tolerant C4 grass that accumulates 80% of its harvestable biomass in approximately 4 m length stems. Stem internode growth is regulated by development, shading, and hormones that modulate cell proliferation in intercalary meristems (IMs). In this study, sorghum stem IMs were localized above the pulvinus at the base of elongating internodes using magnetic resonance imaging, microscopy, and transcriptome analysis. A change in cell morphology/organization occurred at the junction between the pulvinus and internode where LATERAL ORGAN BOUNDARIES (SbLOB), a boundary layer gene, was expressed. Inactivation of an AGCVIII kinase in DDYM (dw2) resulted in decreased SbLOB expression, disrupted IM localization, and reduced internode cell proliferation. Transcriptome analysis identified approximately 1000 genes involved in cell proliferation, hormone signaling, and other functions selectively upregulated in the IM compared with a non-meristematic stem tissue. This cohort of genes is expressed in apical dome stem tissues before localization of the IM at the base of elongating internodes. Gene regulatory network analysis identified connections between genes involved in hormone signaling and cell proliferation. The results indicate that gibberellic acid induces accumulation of growth regulatory factors (GRFs) known to interact with ANGUSTIFOLIA (SbAN3), a master regulator of cell proliferation. GRF:AN3 was predicted to induce SbARF3/ETT expression and regulate SbAN3 expression in an auxin-dependent manner. GRFs and ARFs regulate genes involved in cytokinin and brassinosteroid signaling and cell proliferation. The results provide a molecular framework for understanding how hormone signaling regulates the expression of genes involved in cell proliferation in the stem IM.
PMID: 36038985
Int J Mol Sci , IF:5.923 , 2022 Sep , V23 (19) doi: 10.3390/ijms231911264
Brassinosteroid Signaling Downstream Suppressor BIN2 Interacts with SLFRIGIDA-LIKE to Induce Early Flowering in Tomato.
State Key Laboratory of Crop Stress Biology in Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Xianyang 712100, China.
Brassinosteroid (BR) signaling is very important in plant developmental processes. Its various components interact to form a signaling cascade. These components are widely studied in Arabidopsis; however, very little information is available on tomatoes. Brassinosteroid Insensitive 2 (BIN2), the downstream suppressor of BR signaling, plays a critical role in BR signal pathway, while FRIGIDA as a key suppressor of Flowering Locus C with overexpression could cause early flowering; however, how the BR signaling regulates FRIGIDA homologous protein to adjust flowering time is still unknown. This study identified 12 FRIGIDA-LIKE proteins with a conserved FRIGIDA domain in tomatoes. Yeast two-hybrid and BiFC confirmed that SlBIN2 interacts with 4 SlFRLs, which are sub-cellularly localized in the nucleus. Tissue-specific expression of SlFRLs was observed highly in young roots and flowers. Biological results revealed that SlFRLs interact with SlBIN2 to regulate early flowering. Further, the mRNA level of SlBIN2 also increased in SlFRL-overexpressed lines. The relative expression of SlCPD increased upon SlFRL silencing, while SlDWF and SlBIN2 were decreased, both of which are important for BR signaling. Our research firstly provides molecular evidence that BRs regulate tomato flowering through the interaction between SlFRLs and SlBIN2. This study will promote the understanding of the specific pathway essential for floral regulation.
PMID: 36232562
Int J Mol Sci , IF:5.923 , 2022 Sep , V23 (18) doi: 10.3390/ijms231810922
Heat Stress Decreases Rice Grain Weight: Evidence and Physiological Mechanisms of Heat Effects Prior to Flowering.
Guangxi Key Laboratory of Plant Functional Phytochemicals and Sustainable Utilization, Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences, Guilin 541006, China.; National Key Laboratory of Crop Genetic Improvement, MOA Key Laboratory of Crop Ecophysiology and Farming Systems in the Middle Reaches of the Yangtze River, Huazhong Agricultural University, Wuhan 430070, China.; Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou 570228, China.
Heat stress during the preflowering panicle initiation stage seriously decreases rice grain weight in an invisible way and has not been given enough attention. The current review aims to (i) specify the heat effects on rice grain weight during the panicle initiation stage compared with the most important grain-filling stage; and (ii) discuss the physiological mechanisms of the decreased rice grain weight induced by heat during panicle initiation in terms of assimilate supply and phytohormone regulation, which are key physiological processes directly regulating rice grain weight. We emphasize that the effect of heat during the panicle initiation stage on rice grain weight is more serious than that during the grain-filling stage. Heat stress during the panicle initiation stage induces alterations in endogenous phytohormones, leading to the inhibition of the photosynthesis of functional leaves (source) and the formation of vascular bundles (flow), thus reducing the accumulation and transport of nonstructural carbohydrates and the growth of lemmata and paleae. The disruptions in the "flow" and restrictions in the preanthesis "source" tissue reduce grain size directly and decrease grain plumpness indirectly, resulting in a reduction in the final grain weight, which could be the direct physiological causes of the lower rice grain weight induced by heat during the panicle initiation stage. We highlight the seriousness of preflowering heat stress on rice grain weight, which can be regarded as an invisible disaster. The physiological mechanisms underlying the lower grain weight induced by heat during panicle initiation show a certain novelty because they distinguish this stage from the grain-filling stage. Additionally, a number of genes that control grain size through phytohormones have been summarized, but their functions have not yet been fully tested under heat conditions, except for the Grain Size and Abiotic stress tolerance 1 (GSA1) and BRASSINOSTEROID INSENSITIVE1 (OsBRI1) genes, which are reported to respond rapidly to heat stress. The mechanisms of reduced rice grain weight induced by heat during the panicle initiation stage should be studied in more depth in terms of molecular pathways.
PMID: 36142833
Int J Mol Sci , IF:5.923 , 2022 Sep , V23 (18) doi: 10.3390/ijms231810781
The Characterization of Columnar Apple Gene MdCoL Promoter and Its Response to Abscisic Acid, Brassinosteroid and Gibberellic Acid.
College of Horticulture, Qingdao Agricultural University, Qingdao 266109, China.; Engineering Laboratory of Genetic Improvement of Horticultural Crops of Shandong Province, Qingdao 266109, China.
Columnar apple was an important germplasm resource to develop compact cultivars for labor-saving cultivation and to study fruit tree architecture. MdCoL is a strong candidate gene for controlling the columnar phenotype in apple. In this study, a 2000 bp upstream region of MdCoL was cloned as a full-length promoter, named MdCoLp1. To gain a better understanding of the characterization of the MdCoL promoter, cis-acting elements and the binding sites of transcription factors were predicted and analyzed, and four binary expression vectors consisting of the GUS reporter gene under the control of the MdCoL promoter was transformed into Arabidopsis thaliana to analyze the response to abscisic acid (ABA), brassinosteroid (BR) and gibberellic acid (GA3) of MdCoL promoters. Multiple transcription factors involving TCP, BEL1 and BES1/BZR1 and other transcription factor (TF) binding sites were predicted on the promoter of MdCoL. Histochemical staining showed that both full-length and 5' truncated promoters could initiate GUS expression. The GUS activity was the most in leaf and stem, and mainly concentrated in the fibrovascular tissue, followed by root, and the least activity was observed in silique and flower. In addition, MdCoL expression was mainly localized in the quiescent center (QC) and lateral root growing point of root tip and the vascular tissue of stem and leaf by in situ hybridization. The results of exogenous hormones treatment showed that ABA and BR could activate the activity of the MdCoL promoter, while GA3 had opposite effects. In columnar apple seedlings, ABA treatment could upregulate the expression of MdCoL, but GA3 and BR restrained the transcription level of MdCoL. These results provide the foundation for deciphering the regulatory network of hormones affecting MdCoL transcription.
PMID: 36142696
Int J Mol Sci , IF:5.923 , 2022 Sep , V23 (17) doi: 10.3390/ijms231710149
BES1/BZR1 Family Transcription Factors Regulate Plant Development via Brassinosteroid-Dependent and Independent Pathways.
Guangdong Provincial Key Laboratory of Plant Adaptation and Molecular Design, School of Life Sciences, Guangzhou University, Guangzhou 510006, China.
The BES1/BZR1 family is a plant-specific small group of transcription factors possessing a non-canonical bHLH domain. Genetic and biochemical analyses within the last two decades have demonstrated that members of this family are key transcription factors in regulating the expression of brassinosteroid (BR) response genes. Several recent genetic and evolutionary studies, however, have clearly indicated that the BES1/BZR1 family transcription factors also function in regulating several aspects of plant development via BR-independent pathways, suggesting they are not BR specific. In this review, we summarize our current understanding of this family of transcription factors, the mechanisms regulating their activities, DNA binding motifs, and target genes. We selectively discuss a number of their biological functions via BR-dependent and particularly independent pathways, which were recently revealed by loss-of-function genetic analyses. We also highlight a few possible future directions.
PMID: 36077547
Front Plant Sci , IF:5.753 , 2022 , V13 : P995815 doi: 10.3389/fpls.2022.995815
Morphological characterization and transcriptome analysis of leaf angle mutant bhlh112 in maize [Zea mays L.].
College of Agronomy, Gansu Agricultural University, Lanzhou, China.; Gansu Provincial Key Laboratory of Aridland Crop Science, Gansu Agricultural University, Lanzhou, China.; Gansu Key Laboratory of Crop Improvement & Germplasm Enhancement, Gansu Agricultural University, Lanzhou, China.
Leaf angle is an important agronomic trait in maize [Zea mays L.]. The compact plant phenotype, with a smaller leaf angle, is suited for high-density planting and thus for increasing crop yields. Here, we studied the ethyl methane sulfonate (EMS)-induced mutant bhlh112. Leaf angle and plant height were significantly decreased in bhlh112 compared to the wild-type plants. After treatment of seedlings with exogenous IAA and ABA respectively, under the optimal concentration of exogenous hormones, the variation of leaf angle of the mutant was more obvious than that of the wild-type, which indicated that the mutant was more sensitive to exogenous hormones. Transcriptome analysis showed that the ZmbHLH112 gene was related to the biosynthesis of auxin and brassinosteroids, and involved in the activation of genes related to the auxin and brassinosteroid signal pathways as well as cell elongation. Among the GO enrichment terms, we found many differentially expressed genes (DEGs) enriched in the cell membrane and ribosomal biosynthesis, hormone biosynthesis and signaling pathways, and flavonoid biosynthesis, which could influence cell growth and the level of endogenous hormones affecting leaf angle. Therefore, ZmbHLH112 might regulate leaf angle development through the auxin signaling and the brassinosteroid biosynthesis pathways. 12 genes related to the development of leaf were screened by WGCNA; In GO enrichment and KEGG pathways, the genes were mainly enriched in rRNA binding, ribosome biogenesis, Structural constituent of ribosome; Arabidopsis ribosome RNA methyltransferase CMAL is involved in plant development, likely by modulating auxin derived signaling pathways; The free 60s ribosomes and polysomes in the functional defective mutant rice minute-like1 (rml1) were significantly reduced, resulting in plant phenotypic diminution, narrow leaves, and growth retardation; Hence, ribosomal subunits may play an important role in leaf development. These results provide a foundation for further elucidation of the molecular mechanism of the regulation of leaf angle in maize.
PMID: 36275532
Front Plant Sci , IF:5.753 , 2022 , V13 : P998961 doi: 10.3389/fpls.2022.998961
Interaction of BES1 and LBD37 transcription factors modulates brassinosteroid-regulated root forging response under low nitrogen in arabidopsis.
School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, China.; Department of Crop and Forest Sciences & Agrotecnio Center, Universitat de Lleida, Leida, Spain.
Brassinosteriod (BR) plays important roles in regulation of plant growth, development and environmental responses. BR signaling regulates multiple biological processes through controlling the activity of BES1/BZR1 regulators. Apart from the roles in the promotion of plant growth, BR is also involved in regulation of the root foraging response under low nitrogen, however how BR signaling regulate this process remains unclear. Here we show that BES1 and LBD37 antagonistically regulate root foraging response under low nitrogen conditions. Both the transcriptional level and dephosphorylated level of BES1, is significant induced by low nitrogen, predominantly in root. Phenotypic analysis showed that BES1 gain-of-function mutant or BES1 overexpression transgenic plants exhibits progressive outgrowth of lateral root in response to low nitrogen and BES1 negatively regulates repressors of nitrate signaling pathway and positively regulates several key genes required for NO3 (-) uptake and signaling. In contrast, BES1 knock-down mutant BES1-RNAi exhibited a dramatical reduction of lateral root elongation in response to low N. Furthermore, we identified a BES1 interacting protein, LBD37, which is a negative repressor of N availability signals. Our results showed that BES1 can inhibit LBD37 transcriptional repression on N-responsive genes. Our results thus demonstrated that BES1-LBD37 module acts critical nodes to integrate BR signaling and nitrogen signaling to modulate the root forging response at LN condition.
PMID: 36247555
Front Plant Sci , IF:5.753 , 2022 , V13 : P979033 doi: 10.3389/fpls.2022.979033
OsARF4 regulates leaf inclination via auxin and brassinosteroid pathways in rice.
State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, China.; Hainan Yazhou Bay Seed Laboratory, Sanya, China.; Key Laboratory of Herbage and Endemic Crop Biology of Ministry of Education, Inner Mongolia Key Laboratory of Herbage and Endemic Crop Biotechnology, School of Life Sciences, Inner Mongolia University, Hohhot, China.
Leaf inclination is a vital agronomic trait and is important for plant architecture that affects photosynthetic efficiency and grain yield. To understand the molecular mechanisms underlying regulation of leaf inclination, we constructed an auxin response factor (arf) rice mutant-osarf4-showing increased leaf inclination using CRISPR/Cas9 gene editing technology. OsARF4 encodes a nuclear protein that is expressed in the lamina joint (LJ) at different developmental stages in rice. Histological analysis indicated that an increase in cell differentiation on the adaxial side resulted in increased leaf inclination in the osarf4 mutants; however, OsARF4-overexpressing lines showed a decrease in leaf inclination, resulting in erect leaves. Additionally, a decrease in the content and distribution of indole-3-acetic acid (IAA) in osarf4 mutant led to a greater leaf inclination, whereas the OsARF4-overexpressing lines showed the opposite phenotype with increased IAA content. RNA-sequencing analysis revealed that the expression of genes related to brassinosteroid (BR) biosynthesis and response was different in the mutants and overexpressing lines, suggesting that OsARF4 participates in the BR signaling pathway. Moreover, BR sensitivity assay revealed that OsARF4-overexpressing lines were more sensitive to exogenous BR treatment than the mutants. In conclusion, OsARF4, a transcription factor in auxin signaling, participates in leaf inclination regulation and links auxin and BR signaling pathways. Our results provide a novel insight into l leaf inclination regulation, and have significant implications for improving rice architecture and grain yield.
PMID: 36247537
Front Plant Sci , IF:5.753 , 2022 , V13 : P976341 doi: 10.3389/fpls.2022.976341
Transcriptomic profiling revealed the role of 24-epibrassinolide in alleviating salt stress damage in tall fescue (Festuca arundinacea).
College of Animal Science and Technology, Yangzhou University, Yangzhou, China.; Hunan Tobacco Research Institute, Changsha, China.; Bangladesh Agricultural Research Institute, Dhaka, Bangladesh.
Soil salinization is a major problem all over the world. The accumulation of salt in soil reduces the root water uptake and directly affects plant growth and metabolic activities. Brassinosteroid is a plant hormone that plays an important role in regulation of plant growth and physiological process, including promotion of cell expansion and elongation, signal transduction and stress response. Exogenous 24-epibrassinolide (EBL) has been proved to alleviate various environmental stress in plants. However, the role that EBL plays in salt stress response is still unknown in tall fescue (Festuca arundinacea). In this study, the physiology and molecular mechanisms regulated by exogenous EBL of salt stress response in tall fescue was investigated. Tall fescue plants were divided into four groups, including control (CK), NaCl solution (SALT), 24-epibrassinolide (EBL), NaCl solution + 24-epibrassinolide (SE). During the growth period of tall fescue, we found that electrolyte leakage (EL) and malondialdehyde (MDA) were decreased, chlorophyll (Chl) content and antioxidant enzyme activity were increased in leaves of tall fescue in SE group compared with SALT group, indicating that EBL improved the salt tolerance in grasses. Transcriptomic profiling analysis showed that after 12 h of treatments, 10,265, 13,830 and 10,537 differential genes were expressed in EBL, SALT, and SE groups compared with control, respectively. These differentially expressed genes (DEGs) mainly focused on binding, catalytic activity, cellular process, metabolic process, cellular anatomical entity. Moreover, most of the differential genes were expressed in the plant hormone signal transduction pathway. These results helped us to better understand the mechanism of exogenous 24-epibrassinolide to improve the salt tolerance of tall fescue.
PMID: 36212305
Front Plant Sci , IF:5.753 , 2022 , V13 : P985559 doi: 10.3389/fpls.2022.985559
Brassinosteroid biosynthesis gene OsD2 is associated with low-temperature germinability in rice.
Department of Agronomy, College of Agriculture and Life Sciences, Chungnam National University, Daejeon, South Korea.; Crop Breeding Division, National Institute of Crop Science, Wanju-Gun, South Korea.
In rice, low-temperature germinability (LTG) is essential for stable stand establishment using the direct seeding method in temperate and high-altitude areas. Previously, we reported that the quantitative trait locus qLTG1 is associated with LTG. qLTG1 is also associated with tolerance to several abiotic stresses, such as salt and osmotic conditions. In this study, map-based cloning and sequence analysis indicated that qLTG1 is allelic to DWARF2 (OsD2), which encodes cytochrome P450 D2 (LOC_Os01g10040) involved in brassinosteroid (BR) biosynthesis. Sequence comparison of the two parental lines, Hwaseong and Oryza rufipogon (IRGC 105491), revealed five single nucleotide polymorphisms (SNPs) in the coding region. Three of these SNPs led to missense mutations in OsD2, whereas the other two SNPs were synonymous. We evaluated two T-DNA insertion mutants, viz., overexpression (OsD2-OE) and knockdown (OsD2-KD) mutants of OsD2, with the Dongjin genetic background. OsD2-KD plants showed a decrease in LTG and grain size. In contrast, OsD2-OE plants showed an increase in grain size and LTG. We also examined the expression levels of several BR signaling and biosynthetic genes using the T-DNA insertion mutants. Gene expression analysis and BR application experiments demonstrated that BR enhanced the seed germination rate under low-temperature conditions. These results suggest that OsD2 is associated with the regulation of LTG and improving grain size. Thus, OsD2 may be a suitable target for rice breeding programs to improve rice yield and LTG.
PMID: 36204076
Plant Cell Physiol , IF:4.927 , 2022 Oct doi: 10.1093/pcp/pcac149
Integration of auxin, brassinosteroid and cytokinin in the regulation of rice yield.
Department of Life Sciences, POSTECH Biotech Center, Pohang University of Science and Technology, Pohang, Korea.; Department of Botany, Hindu Girls College, Maharshi Dayanand University, Sonipat 131001, India.; Institute of Research and Development, Duy Tan University, 03 Quang Trung, Da Nang, Vietnam.; Institute of Genomics for Crop Abiotic Stress Tolerance, Department of Plant and Soil Science, Texas Tech University, Lubbock, TX 79409, USA.
Crop varieties with a high yield are most desirable in the present context of the ever-growing human population. Mostly the yield traits are governed by a complex of numerous molecular and genetic facets modulated by various quantitative trait loci (QTLs). With the identification and molecular characterizations of yield-associated QTLs over recent years, the central role of phytohormones in regulating plant yield is becoming more apparent. Most often, different groups of phytohormones work in close association to orchestrate yield attributes. Understanding this crosstalk would thus provide new venues for phytohormone pyramiding by editing a single gene or QTL(s) for yield improvement. Here, we review a few important findings to integrate the knowledge on the roles of auxin, brassinosteroid and cytokinin and how a single gene or a QTL could govern crosstalk among multiple phytohormones to determine the yield traits.
PMID: 36255097
Plant Sci , IF:4.729 , 2022 Dec , V325 : P111482 doi: 10.1016/j.plantsci.2022.111482
OsCPD1 and OsCPD2 are functional brassinosteroid biosynthesis genes in rice.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: hdzhan@njau.edu.cn.; State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.; College of Life Science, Nanjing Agricultural University, Nanjing 210095, China.
CONSTITUTIVE PHOTOMORPHOGENIC DWARF (CPD), member of the CYP90A family of cytochrome P450 (CYP450) monooxygenase, is an essential component of brassinosteroids (BRs) biosynthesis pathway. Compared with a single CPD/CYP90A1 in Arabidopsis thaliana, two highly homologous CPD genes, OsCPD1/CYP90A3 and OsCPD2/CYP90A4, are present in rice genome. There is still no genetic evidence so far about the requirement of OsCPD1 and OsCPD2 in rice BR biosynthesis. In this study, we reported the functional characterization of OsCPD genes using CRISPR/Cas9 gene editing technology. The overall growth and development of oscpd1 and oscpd2 single knock-out mutants was indistinguishable from the wild-type, whereas, the oscpd1 oscpd2 double mutant displayed multiple and obvious BR-related defects. Cytological analyses further indicated the defective cell elongation in oscpd1 oscpd2 double mutant. The oscpd double mutants had a lower endogenous BR level and could be restored by the application of the brassinolide (BL). Moreover, overexpression of OsCPD1 and OsCPD2 led to a typical BR enhanced phenotype, with enlarged leaf angle and increased grain size. Taken together, our results provide direct genetic evidence that OsCPD1 and OsCPD2 play essential and redundant roles in maintenance of plant architecture by modulating BR biosynthesis in rice.
PMID: 36191635
Plant Mol Biol , IF:4.076 , 2022 Oct doi: 10.1007/s11103-022-01313-5
GhBES1 mediates brassinosteroid regulation of leaf size by activating expression of GhEXO2 in cotton (Gossypium hirsutum).
Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Henan, 450001, Zhengzhou, China.; State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, Henan, China.; State Key Laboratory of Cotton Biology (Hebei Base), Hebei Agricultural University, Baoding, 071001, Hebei, China.; College of Chemistry, Zhengzhou University, Henan, 450001, Zhengzhou, China.; Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Henan, 450001, Zhengzhou, China. liuzhaocaas@163.com.; Zhengzhou Research Base, State Key Laboratory of Cotton Biology, School of Agricultural Sciences, Zhengzhou University, Henan, 450001, Zhengzhou, China. yangzuoren@caas.cn.; State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, Henan, China. yangzuoren@caas.cn.
KEY MESSAGE: We proposed a working model of BR to promote leaf size through cell expansion. In the BR signaling pathway, GhBES1 affects cotton leaf size by binding to and activating the expression of the E-box element in the GhEXO2 promoter region. Brassinosteroid (BR) is an essential phytohormone that controls plant growth. However, the mechanisms of BR regulation of leaf size remain to be determined. Here, we found that the BR deficient cotton mutant pagoda1 (pag1) had a smaller leaf size than wild-type CRI24. The expression of EXORDIUM (GhEXO2) gene, was significantly downregulated in pag1. Silencing of BRI1-EMS-SUPPRESSOR 1 (GhBES1), inhibited leaf cell expansion and reduced leaf size. Overexpression of GhBES1.4 promoted leaf cell expansion and enlarged leaf size. Expression analysis showed GhEXO2 expression positively correlated with GhBES1 expression. In plants, altered expression of GhEXO2 promoted leaf cell expansion affecting leaf size. Furthermore, GhBES1.4 specifically binds to the E-box elements in the GhEXO2 promoter, inducing its expression. RNA-seq data revealed many down-regulated genes related to cell expansion in GhEXO2 silenced plants. In summary, we discovered a novel mechanism of BR regulation of leaf size through GhBES1 directly activating the expression of GhEXO2.
PMID: 36271986
Plants (Basel) , IF:3.935 , 2022 Oct , V11 (19) doi: 10.3390/plants11192630
Three-Fluorophore FRET Enables the Analysis of Ternary Protein Association in Living Plant Cells.
Center for Plant Molecular Biology (ZMBP), University of Tubingen, 72076 Tubingen, Germany.; Institute for Physical & Theoretical Chemistry, University of Tubingen, 72076 Tubingen, Germany.; Centre for Organismal Studies (COS), University of Heidelberg, 69117 Heidelberg, Germany.
Protein-protein interaction studies provide valuable insights into cellular signaling. Brassinosteroid (BR) signaling is initiated by the hormone-binding receptor Brassinosteroid Insensitive 1 (BRI1) and its co-receptor BRI1 Associated Kinase 1 (BAK1). BRI1 and BAK1 were shown to interact independently with the Receptor-Like Protein 44 (RLP44), which is implicated in BRI1/BAK1-dependent cell wall integrity perception. To demonstrate the proposed complex formation of BRI1, BAK1 and RLP44, we established three-fluorophore intensity-based spectral Forster resonance energy transfer (FRET) and FRET-fluorescence lifetime imaging microscopy (FLIM) for living plant cells. Our evidence indicates that RLP44, BRI1 and BAK1 form a ternary complex in a distinct plasma membrane nanodomain. In contrast, although the immune receptor Flagellin Sensing 2 (FLS2) also forms a heteromer with BAK1, the FLS2/BAK1 complexes are localized to other nanodomains. In conclusion, both three-fluorophore FRET approaches provide a feasible basis for studying the in vivo interaction and sub-compartmentalization of proteins in great detail.
PMID: 36235497
Plants (Basel) , IF:3.935 , 2022 Sep , V11 (19) doi: 10.3390/plants11192565
Isolation and Functional Characterization of Soybean BES1/BZR1 Homolog 3-Like 1 (GmBEH3L1) Associated with Dehydration Sensitivity and Brassinosteroid Signaling in Arabidopsis thaliana.
Department of Applied Biology, Chonnam National University, Gwangju 61186, Korea.; Department of Basic Science, Buon Ma Thuot University of Medicine and Pharmacy, Buon Ma Thuot 630000, Vietnam.; Department of Biochemistry and Biophysics, Texas A&M University, 300 Olsen Blvd, College Station, TX 77843-2128, USA.; Department of Integrative Food, Bioscience and Biotechnology, Chonnam National University, Gwangju 61186, Korea.; Department of Biological Sciences, Pusan National University, Busan 46241, Korea.
Brassinosteroid (BR) is an important steroid hormone that regulates plant development, abscisic acid (ABA) signaling, and responses to abiotic stress. We previously demonstrated that BEH3 (BES1/BZR1 Homolog 3) of Arabidopsis thaliana regulates dehydration and ABA responses by mediating proline metabolism. Furthermore, BEH3 negatively regulates BR-mediated hypocotyl elongation in dark-grown seedlings. However, the roles of BEH3 ortholog genes in the osmotic stress response of plants have remained largely unknown. Here, GmBEH3L1 (Glycine max BEH3-Like 1), a soybean (G. max) ortholog of the BEH3 gene of A. thaliana, was isolated and functionally characterized. GmBEH3L1 is induced by ABA, dehydration, and drought conditions. The GmBEH3L1-overexpressing transgenic lines (GmBEH3L1-OE/beh3) with the beh3 mutant background have ABA- and dehydration-sensitive phenotypes during early seedling growth, implying that GmBEH3L1 is involved in both osmotic stress and ABA sensitivity as a negative regulator in A. thaliana. Consistent with these results, GmBEH3L1-OE/beh3 complemental lines exhibit decreased expression levels of ABA- or dehydration-inducible genes. Under darkness, GmBEH3L1-OE/beh3 complemental lines display a short hypocotyl length compared to the beh3 mutant, indicating that GmBEH3L1 is linked to BR signaling. Together, our data suggest that GmBEH3L1 participates negatively in ABA and dehydration responses through BR signaling.
PMID: 36235431
Plants (Basel) , IF:3.935 , 2022 Sep , V11 (17) doi: 10.3390/plants11172324
Identification of QTL under Brassinosteroid-Combined Cold Treatment at Seedling Stage in Rice Using Genotyping-by-Sequencing (GBS).
Key Laboratory of Agricultural Biotechnology of Liaoning Province, College of Biosciences and Biotechnology, Shenyang Agricultural University, Shenyang 110866, China.; Rice Research Institute, College of Agronomy, Shenyang Agricultural University, Shenyang 110866, China.; Rice Research Institute, Jiangxi Academy of Agricultural Sciences, Nanchang 330200, China.; Department of Agronomy, College of Agriculture, Purdue University, West Lafayette, IN 47907, USA.
Cold stress is a major threat to the sustainability of rice yield. Brassinosteroids (BR) application can enhance cold tolerance in rice. However, the regulatory mechanism related to cold tolerance and the BR signaling pathway in rice has not been clarified. In the current study, the seedling shoot length (SSL), seedling root length (SRL), seedling dry weight (SDW), and seedling wet weight (SWW) were used as the indices for identifying cold tolerance under cold stress and BR-combined cold treatment in a backcross recombinant inbred lines (BRIL) population. According to the phenotypic characterization for cold tolerance and a high-resolution SNP genetic map obtained from the GBS technique, a total of 114 QTLs were identified, of which 27 QTLs were detected under cold stress and 87 QTLs under BR-combined cold treatment. Among them, the intervals of many QTLs were coincident under different treatments, as well as different traits. A total of 13 candidate genes associated with cold tolerance or BR pathway, such as BRASSINAZOLE RESISTANT1 (OsBZR1), OsWRKY77, AP2 domain-containing protein, zinc finger proteins, basic helix-loop-helix (bHLH) protein, and auxin-induced protein, were predicted. Among these, the expression levels of 10 candidate genes were identified under different treatments in the parents and representative BRIL individuals. These results were helpful in understanding the regulation relationship between cold tolerance and BR pathway in rice.
PMID: 36079705
Curr Protoc , 2022 Oct , V2 (10) : Pe562 doi: 10.1002/cpz1.562
Maize Seedling Growth and Hormone Response Assays Using the Rolled Towel Method.
Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa.; Current address: Corteva Agriscience, 8325 NW 62nd Ave, Johnston, Iowa.
Root system architecture is a critical factor in maize health and stress resilience. Determining the genetic and environmental factors that shape maize root system architecture is an active research area. However, the ability to phenotype juvenile root systems is hindered by the use of field-grown and soil-based systems. An alternative to soil- and field-based growing conditions for maize seedlings is a controlled environment with a soil-free medium, which can facilitate root system phenotyping. Here, we describe how to grow maize under soil-free conditions for up to 12 days to facilitate root phenotyping. Maize seeds are sterilized and planted on specialized seed germination paper to minimize fungal contamination and ensure synchronized seedling growth, followed by imaging at the desired time point. The root images are then analyzed to quantify traits of interest, such as primary root length, lateral root density, seminal root length, and seminal root number. In addition, juvenile shoot traits can be quantified using manual annotation methods. We also outline the steps for performing rigorous hormone response assays for four classical phytohormones: auxin, brassinosteroid, cytokinin, and jasmonic acid. This protocol can be rapidly scaled up and is compatible with genetic screens and sample collection for downstream molecular analyses such as transcriptomics and proteomics. (c) 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Maize seedling rolled towel assay and phenotyping Basic Protocol 2: Maize seedling hormone response assays using the rolled towel assay.
PMID: 36194012
Plant Commun , 2022 Sep : P100450 doi: 10.1016/j.xplc.2022.100450
The U-box Ubiquitin Ligase TUD1 Promotes Brassinosteroid-Induced GSK2 Degradation in Rice.
National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China.; State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, the Innovative Academy for Seed Design, Chinese Academy of Sciences, Beijing 100101, China.; National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China; National Nanfan Research Institute, Chinese Academy of Agricultural Sciences, Sanya 572024, China. Electronic address: tonghongning@caas.cn.
Brassinosteroids (BRs) are a class of steroid hormones having great potentials in crop improvement. De-repression is usually one of the key events in hormone signaling. However, how the stability of GSK2, the central negative regulator of BR signaling in rice (Oryza sativa), is regulated by BRs remains elusive. Here we identify TUD1, the U-box ubiquitin ligase, as a GSK2-interacting protein by yeast two-hybrid screening. We show that TUD1 is able to directly interact with GSK2 and ubiquitinate the protein. Phenotypes of tud1 mutant are highly similar to the plants with constitutively activated GSK2. Consistently, the GSK2 protein is accumulated in tud1 compared with that in wild type. In addition, inhibition of BR synthesis promotes GSK2 accumulation whereas suppresses TUD1 stability. By contrast, BRs can induce GSK2 degradation but promote TUD1 accumulation. Furthermore, GSK2 degradation process is largely impaired in tud1 mutant in response to BR. In conclusion, our study demonstrates the role of TUD1 in responsible for BR-induced GSK2 degradation, thereby advances a critical step in understanding BR signaling pathway in rice.
PMID: 36127877
Plant Commun , 2022 Sep , V3 (5) : P100348 doi: 10.1016/j.xplc.2022.100348
Deubiquitination of BES1 by UBP12/UBP13 promotes brassinosteroid signaling and plant growth.
Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore.; Temasek Life Sciences Laboratory, National University of Singapore, 1 Research Link, Singapore 117604, Singapore. Electronic address: chua@rockefeller.edu.
As a key transcription factor in the brassinosteroid (BR) signaling pathway, the activity and expression of BES1 (BRI1-EMS-SUPPRESSOR 1) are stringently regulated. BES1 degradation is mediated by ubiquitin-related 26S proteasomal and autophagy pathways, which attenuate and terminate BR signaling; however, the opposing deubiquitinases (DUBs) are still unknown. Here, we showed that the ubp12-2w/13-3 double mutant phenocopies the BR-deficient dwarf mutant, suggesting that the two DUBs UBP12/UBP13 antagonize ubiquitin-mediated degradation to stabilize BES1. These two DUBs can trim tetraubiquitin with K46 and K63 linkages in vitro. UBP12/BES1 and UBP13/BES1 complexes are localized in both cytosol and nuclei. UBP12/13 can deubiquitinate polyubiquitinated BES1 in vitro and in planta, and UBP12 interacts with and deubiquitinates both inactive, phosphorylated BES1 and active, dephosphorylated BES1 in vivo. UBP12 overexpression in BES1(OE) plants significantly enhances cell elongation in hypocotyls and petioles and increases the ratio of leaf length to width compared with BES1(OE) or UBP12(OE) plants. Hypocotyl elongation and etiolation result from elevated BES1 levels because BES1 degradation is retarded by UBP12 in darkness or in light with BR. Protein degradation inhibitor experiments show that the majority of BES1 can be degraded by either the proteasomal or the autophagy pathway, but a minor BES1 fraction remains pathway specific. In conclusion, UBP12/UBP13 deubiquitinate BES1 to stabilize the latter as a positive regulator for BR responses.
PMID: 35706355