Dev Cell , IF:10.092 , 2020 Sep doi: 10.1016/j.devcel.2020.08.005
The GSK3-like Kinase BIN2 Is a Molecular Switch between the Salt Stress Response and Growth Recovery in Arabidopsis thaliana.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.; Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064, China.; State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China. Electronic address: guoyan@cau.edu.cn.
Plant stress responses involve dynamic growth regulation. Growth is restricted in harsh environmental conditions and is rapidly restored when conditions improve. Here, we identified BIN2, a glycogen synthase kinase 3 (GSK3)-like kinase, as a molecular switch in the transition to robust growth after salt stress in Arabidopsis thaliana. In the rapid recovery phase after salt stress, the calcium sensors SOS3 and SCaBP8 perceive a calcium signal and promote BIN2 localization to the plasma membrane to repress the salt stress response, and BIN2 inhibits SOS2 activity and enhances growth by releasing BZR1/BES1 transcriptional activity. The expression of stress- and brassinosteroid-responsive genes is coordinately regulated during this process. bin2-3bil1 and bin2-3bil2 mutants defective in BIN2 and its homologs BIL1 and BIL2, respectively, are hyposensitive to salt stress. Our study suggests that salt signaling modulates the subcellular localization and interactions of BIN2. By phosphorylating different substrates, BIN2 regulates the salt stress response and growth recovery.
PMID: 32891194
Plant Cell , IF:9.618 , 2020 Sep doi: 10.1105/tpc.20.00384
Endocytosis of BRASSINOSTEROID INSENSITIVE1 is Partly Driven by a Canonical Tyrosine-based Motif.
Texas A&M CITY: College Station STATE: Texas United States Of America [US].; VIB-UGent CITY: Ghent Belgium [BE].; Ghent University CITY: Ghent Belgium [BE].; Institute of Science and Technology Austria (IST Austria) CITY: Klosterneuburg Austria [AT].; VIB/UGent CITY: Ghent Belgium [BE].; University of Illinois Urbana-Champaign CITY: Urbana United States Of America [US].; VIB/UGent CITY: Gent STATE: Belgie Belgium [BE].; CNRS/CEA/Univ. Paris Sud CITY: Gif-sur-Yvette France [FR].; LRSV CNRS CITY: Castanet-Tolosan POSTAL_CODE: 31320 France [FR].; VIB/UGent CITY: Gent STATE: Belgie POSTAL_CODE: 9052 Belgium [BE].; VIB-UGent CITY: Ghent POSTAL_CODE: 9052 Belgium [BE] eurus@psb.vib-ugent.be.
Clathrin-mediated endocytosis (CME) and its core endocytic machinery are evolutionarily conserved across all eukaryotes. In mammals, the heterotetrameric adaptor protein complex-2 (AP-2) sorts plasma membrane (PM) cargoes into vesicles through the recognition of motifs based on tyrosine or di-leucine in their cytoplasmic tails. However, in plants, very little is known on how PM proteins are sorted for CME and whether similar motifs are required. In Arabidopsis thaliana, the brassinosteroid (BR) receptor, BR INSENSITIVE1 (BRI1), undergoes endocytosis that depends on clathrin and AP-2. Here we demonstrate that BRI1 binds directly to the medium AP-2 subunit, AP2M. The cytoplasmic domain of BRI1 contains five putative canonical surface-exposed tyrosine-based endocytic motifs. The tyrosine-to-phenylalanine substitution in Y898KAI reduced BRI1 internalization without affecting its kinase activity. Consistently, plants carrying the BRI1Y898F mutation were hypersensitive to BRs. Our study demonstrates that AP-2-dependent internalization of PM proteins via the recognition of functional tyrosine motifs also operates in plants.
PMID: 32958564
Plant Cell Environ , IF:6.362 , 2020 Oct , V43 (10) : P2325-2335 doi: 10.1111/pce.13846
Balancing growth and adaptation to stress: Crosstalk between brassinosteroid and abscisic acid signaling.
State Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.; University of Chinese Academy of Sciences, Beijing, China.
Plant growth and development are plastic and canadapt to environmental changes. In this process different plant hormones coordinate to modulate plant growth and environmental interactions. In this article, we describe the individual brassinosteroid (BR) and abscisic acid (ABA) signaling pathways, emphasize the specific regulatory mechanisms between ABA and BR responses and discuss how both phytohormones coordinate growth, development and stress responses in plants. BR signaling is essential for plant development, while ABA signaling is activated to ensure plants survive stress. The crosstalk between BR and ABA, especially protein phosphorylation, protein stability control and downstream transcription control of key components of both pathways are discussed in terms of modulating plant development and stress adaptation.
PMID: 32671865
Ecotoxicol Environ Saf , IF:4.872 , 2020 Sep , V207 : P111081 doi: 10.1016/j.ecoenv.2020.111081
Brassinosteroid and hydrogen peroxide improve photosynthetic machinery, stomatal movement, root morphology and cell viability and reduce Cu- triggered oxidative burst in tomato.
Plant Physiology and Biochemistry Section, Department of Botany, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, India.; Plant Physiology and Biochemistry Section, Department of Botany, Faculty of Life Sciences, Aligarh Muslim University, Aligarh, 202002, India. Electronic address: qazi_farid@yahoo.com.; Vegetable Research Institute, Guangdong Academy of Agricultural Sciences/ Guangdong Key Laboratory for New Technology Research of Vegetables, Guangzhou, 510640, China.
Brassinosteroids and hydrogen peroxide (H2O2) are extensively used to combat several environmental factors, including heavy metal stress in plants, but their cumulative impact on the maintenance of copper (Cu) homeostasis in plants could not be dissected at elevated level. This study was executed to explore the roles of 24-epibrassinolide (EBL; foliar) and H2O2 (root dipping) in resilience of tomato (Solanum lycopersicum L.) plants to Cu stress. The cumulative effect of EBL and H2O2 in tomato plants grown under Cu stress (10 or 100 mg kg(-1) soil) were assessed. Roots of 20 d old plants were submerged in 0.1 mM of H2O2 solution for 4 h and subsequently transplanted in the soil-filled earthen pots and at 30 day after transplantation (DAT), the plants were sprinkled with deionized water (control), and/or 10(-8) M EBL and plant performances were evaluated at 40 DAT. High Cu (100 mg kg(-1) soil) concentration considerably reduced photosynthetic efficacy, cell viability, and plant growth, and deformed chloroplast ultrastructure and root morphology with altered stomatal behavior, but boosted the activity of antioxidant enzymes, proline content and electrolyte leakage in the leaves of tomato. Moreover, EBL and H2O2 implemented through distinct modes improved photosynthetic efficiency, modified chloroplast ultrastructure, stomatal behavior, root structure, cell viability and production of antioxidants and proline (osmolyte) that augmented resilience of tomato plants to Cu stress. This study revealed the potential of EBL and H2O2 applied through distinct mode could serve as an effective strategy to reduce Cu-toxicity in tomato crop.
PMID: 32927154
Int J Mol Sci , IF:4.556 , 2020 Sep , V21 (18) doi: 10.3390/ijms21186616
Silencing of HvGSK1.1-A GSK3/SHAGGY-Like Kinase-Enhances Barley (Hordeum vulgare L.) Growth in Normal and in Salt Stress Conditions.
Department of Genetic Engineering, Plant Breeding and Acclimatization, Institute-National Research Institute, Radzikow, 05-870 Blonie, Poland.; Department of Computational Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Uniwersytetu Poznanskiego 6, 61-614 Poznan, Poland.; Department of Functional Genomics, Plant Breeding and Acclimatization, Institute-National Research Institute, Radzikow, 05-870 Blonie, Poland.
Glycogen synthase kinase 3 (GSK3) is a highly conserved kinase present in all eukaryotes and functions as a key regulator of a wide range of physiological and developmental processes. The kinase, known in land plants as GSK3/SHAGGY-like kinase (GSK), is a key player in the brassinosteroid (BR) signaling pathway. The GSK genes, through the BRs, affect diverse developmental processes and modulate responses to environmental factors. In this work, we describe functional analysis of HvGSK1.1, which is one of the GSK3/SHAGGY-like orthologs in barley. The RNAi-mediated silencing of the target HvGSK1.1 gene was associated with modified expression of its paralogs HvGSK1.2, HvGSK2.1, HvGSK3.1, and HvGSK4.1 in plants grown in normal and in salt stress conditions. Low nucleotide similarity between the silencing fragment and barley GSK genes and the presence of BR-dependent transcription factors' binding sites in promoter regions of barley and rice GSK genes imply an innate mechanism responsible for co-regulation of the genes. The results of the leaf inclination assay indicated that silencing of HvGSK1.1 and the changes of GSK paralogs enhanced the BR-dependent signaling in the plants. The strongest phenotype of transgenic lines with downregulated HvGSK1.1 and GSK paralogs had greater biomass of the seedlings grown in normal conditions and salt stress as well as elevated kernel weight of plants grown in normal conditions. Both traits showed a strong negative correlation with the transcript level of the target gene and the paralogs. The characteristics of barley lines with silenced expression of HvGSK1.1 are compatible with the expected phenotypes of plants with enhanced BR signaling. The results show that manipulation of the GSK-encoding genes provides data to explore their biological functions and confirm it as a feasible strategy to generate plants with improved agricultural traits.
PMID: 32927724
Planta , IF:3.39 , 2020 Sep , V252 (4) : P48 doi: 10.1007/s00425-020-03456-5
Self-transcriptional repression of the Arabidopsis NAC transcription factor ATAF2 and its genetic interaction with phytochrome A in modulating seedling photomorphogenesis.
Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164, USA.; Department of Plant Pathology, Washington State University, Pullman, WA, 99164, USA.; Department of Crop and Soil Sciences, Washington State University, Pullman, WA, 99164, USA. mmneff@wsu.edu.
MAIN CONCLUSION: The NAC transcription factor ATAF2 suppresses its own transcription via self-promoter binding. ATAF2 genetically interacts with the circadian regulator CCA1 and phytochrome A to modulate seedling photomorphogenesis in Arabidopsis thaliana. ATAF2 (ANAC081) is a NAC (NAM, ATAF and CUC) transcription factor (TF) that participates in the regulation of disease resistance, stress tolerance and hormone metabolism in Arabidopsis thaliana. We previously reported that ATAF2 promotes Arabidopsis hypocotyl growth in a light-dependent manner via transcriptionally suppressing the brassinosteroid (BR)-inactivating cytochrome P450 genes BAS1 (CYP734A1, formerly CYP72B1) and SOB7 (CYP72C1). Assays using low light intensities suggest that the photoreceptor phytochrome A (PHYA) may play a more critical role in ATAF2-regulated photomorphogenesis than phytochrome B (PHYB) and cryptochrome 1 (CRY1). In addition, ATAF2 is also regulated by the circadian clock. The core circadian TF CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) physically interacts with ATAF2 at the DNA-protein and protein-protein levels, and both differentially suppress BAS1- and SOB7-mediated BR catabolism. In this research, we show that ATAF2 can bind its own promoter as a transcriptional self-repressor. This self-feedback-suppression loop is a typical feature of multiple circadian-regulated genes. Additionally, ATAF2 and CCA1 synergistically suppress seedling photomorphogenesis as reflected by the light-dependent hypocotyl growth analysis of their single and double gene knock-out mutants. Similar fluence-rate response assays using ATAF2 and photoreceptor (PHYB, CRY1 and PHYA) knock-out mutants demonstrate that PHYA is required for ATAF2-regulated photomorphogenesis in a wide range of light intensities. Furthermore, disruption of PHYA can suppress the BR-insensitive hypocotyl-growth phenotype of ATAF2 loss-of-function seedlings in the light, but not in darkness. Collectively, our results provide a genetic interaction synopsis of the circadian-clock-photomorphogenesis-BR integration node involving ATAF2, CCA1 and PHYA.
PMID: 32892254
Plant Mol Biol , IF:3.302 , 2020 Oct , V104 (3) : P263-281 doi: 10.1007/s11103-020-01040-9
Plant-specific Dof transcription factors VASCULAR-RELATED DOF1 and VASCULAR-RELATED DOF2 regulate vascular cell differentiation and lignin biosynthesis in Arabidopsis.
Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.; Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto, 611-0011, Japan.; Research Unit for Development of Global Sustainability, Kyoto University, Uji, Gokasho, Kyoto, 611-0011, Japan.; Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan. demura@bs.naist.jp.; Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan. misato@edu.k.u-tokyo.ac.jp.; Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, 277-8562, Japan. misato@edu.k.u-tokyo.ac.jp.
KEY MESSAGE: Plant-specific Dof transcription factors VDOF1 and VDOF2 are novel regulators of vascular cell differentiation through the course of a lifetime in Arabidopsis, with shifting their transcriptional target genes. Vascular system is one of critical tissues for vascular plants to transport low-molecular compounds, such as water, minerals, and the photosynthetic product, sucrose. Here, we report the involvement of two Dof transcription factors, named VASCULAR-RELATED DOF1 (VDOF1)/VDOF4.6 and VDOF2/VDOF1.8, in vascular cell differentiation and lignin biosynthesis in Arabidopsis. VDOF genes were expressed in vascular tissues, but the detailed expression sites were partly different between VDOF1 and VDOF2. Vein patterning and lignin analysis of VDOF overexpressors and double mutant vdof1 vdof2 suggested that VDOF1 and VDOF2 would function as negative regulators of vein formation in seedlings, and lignin deposition in inflorescence stems. Interestingly, effects of VDOF overexpression in lignin deposition were different by developmental stages of inflorescence stems, and total lignin contents were increased and decreased in VDOF1 and VDOF2 overexpressors, respectively. RNA-seq analysis of inducible VDOF overexpressors demonstrated that the genes for cell wall biosynthesis, including lignin biosynthetic genes, and the transcription factor genes related to stress response and brassinosteroid signaling were commonly affected by VDOF1 and VDOF2 overexpression. Taken together, we concluded that VDOF1 and VDOF2 are novel regulators of vascular cell differentiation through the course of a lifetime, with shifting their transcriptional target genes: in seedlings, the VDOF genes negatively regulate vein formation, while at reproductive stages, the VDOF proteins target lignin biosynthesis.
PMID: 32740898
Funct Plant Biol , IF:2.617 , 2020 Sep doi: 10.1071/FP20205
Hydrogen sulfide induced by hydrogen peroxide mediates brassinosteroid-induced stomatal closure of Arabidopsis thaliana.
The role of hydrogen sulfide (H2S) and its relationship with hydrogen peroxide (H2O2) in brassinosteroid-induced stomatal closure in Arabidopsis thaliana (L.) Heynh. were investigated. In the present study, 2,4-epibrassinolide (EBR, a bioactive BR) induced stomatal closure in the wild type, the effects were inhibited by H2S scavenger and synthesis inhibitors, and H2O2 scavengers and synthesis inhibitor. However, EBR failed to close the stomata of mutants Atl-cdes, Atd-cdes, AtrbohF and AtrbohD/F. Additionally, EBR induced increase of L-/D-cysteine desulfhydrase (L-/D-CDes) activity, H2S production, and H2O2 production in the wild type, and the effects were inhibited by H2S scavenger and synthesis inhibitors, and H2O2 scavengers and synthesis inhibitor respectively. Furthermore, EBR increased H2O2 levels in the guard cells of AtrbohD mutant, but couldn't raise H2O2 levels in the guard cells of AtrbohF and AtrbohD/F mutants. Next, scavengers and synthesis inhibitor of H2O2 could significantly inhibit EBR-induced rise of L-/D-CDes activity and H2S production in the wild type, but H2S scavenger and synthesis inhibitors failed to repress EBR-induced H2O2 production. EBR could increase H2O2 levels in the guard cells of Atl-cdes and Atd-cdes mutants, but EBR failed to induce increase of L-/D-CDes activity and H2S production in AtrbohF and AtrbohD/F mutants. Therefore, we conclude that H2S and H2O2 are involved in the signal transduction pathway of EBR-induced stomatal closure. Altogether, our data suggested that EBR induces AtrbohF-dependent H2O2 production and subsequent AtL-CDes-/AtD-CDes-catalysed H2S production, and finally closes stomata in A. thaliana.
PMID: 32910883