scholarly journals Arabidopsis exoribonuclease USB1 interacts with the PPR-domain protein SOAR1 to negatively regulate abscisic acid signaling

2020 ◽  
Vol 71 (19) ◽  
pp. 5837-5851
Author(s):  
Yu Ma ◽  
Shang Zhang ◽  
Chao Bi ◽  
Chao Mei ◽  
Shang-Chuan Jiang ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Regulation Of Gene Expression ◽  
Mrna Splicing ◽  
Plant Responses ◽  
Aba Signaling ◽  
Pentatricopeptide Repeat ◽  
Spliceosome Assembly ◽  
Early Seedling ◽  
Post Transcriptional Regulation ◽  
Early Seedling Development

Abstract Signaling by the phytohormone abscisic acid (ABA) involves pre-mRNA splicing, a key process of post-transcriptional regulation of gene expression. However, the regulatory mechanism of alternative pre-mRNA splicing in ABA signaling remains largely unknown. We previously identified a pentatricopeptide repeat protein SOAR1 (suppressor of the ABAR-overexpressor 1) as a crucial player downstream of ABAR (putative ABA receptor) in ABA signaling. In this study, we identified a SOAR1 interaction partner USB1, which is an exoribonuclease catalyzing U6 production for spliceosome assembly. We reveal that together USB1 and SOAR1 negatively regulate ABA signaling in early seedling development. USB1 and SOAR1 are both required for the splicing of transcripts of numerous genes, including those involved in ABA signaling pathways, suggesting that USB1 and SOAR1 collaborate to regulate ABA signaling by affecting spliceosome assembly. These findings provide important new insights into the mechanistic control of alternative pre-mRNA splicing in the regulation of ABA-mediated plant responses to environmental cues.

scholarly journals Interplay between Brassinosteroid and ABA signaling during early seedling development

2017 ◽  
Vol 44 (3) ◽  
pp. 264-270 ◽  
Author(s):  
Hyemin Kim ◽  
Jeongeui Hong ◽  
Yong-Gu Cho ◽  
Kwon Kyoo Kang ◽  
Hojin Ryu
Keyword(s):  
Seedling Development ◽  
Aba Signaling ◽  
Early Seedling ◽  
Early Seedling Development

scholarly journals O-fucosylation of CPN20 by SPINDLY Derepresses Abscisic Acid Signaling During Seed Germination and Seedling Development

2021 ◽  
Vol 12 ◽  
Author(s):  
Lin Liang ◽  
Qi Wang ◽  
Zihao Song ◽  
Yaxin Wu ◽  
Qing Liang ◽  
...  
Keyword(s):  
Seed Germination ◽  
Mammalian Cells ◽  
Electron Transfer Dissociation ◽  
Seedling Development ◽  
Aba Signaling ◽  
Early Seedling ◽  
Aba Insensitive ◽  
Early Seedling Development

SPINDLY is involved in some aspects of plant development. However, the nature of this protein as an O-fucosyltransferase was recently discovered. In this study, we show that SPINDLY (SPY) interacts with CPN20 in yeast two-hybrid and split-luc assays, and the interaction is promoted by ABA. CPN20 is a chloroplast-localized co-chaperonin that negatively regulates ABAR-mediated ABA signaling. By using Electron Transfer Dissociation-MS/MS analysis, two O-fucosylation sites, e.g., 116th and 119th threonines, were detected in ectopically expressed CPN20 in mammalian cells and in Arabidopsis. The O-fucosylation at both threonine residues was confirmed by in vitro peptide O-fucosylation assay. We further show that CPN20 accumulates in the chloroplast of spy mutants, suggesting that SPY negatively regulates CPN20 localization in the chloroplast. In vivo protein degradation assay along with CPN20 localization behavior suggest that import of CPN20 into the chloroplast is negatively regulated by SPY. Genetic analysis shows that ABA insensitive phenotypes of spy-3 in terms of seed germination and early seedling development are partially suppressed by the cpn20 mutation, suggesting that CPN20 acts downstream of SPY in this ABA signaling pathway and that there may exist other pathways in parallel with CPN20. Collectively, the above data support the notion that the O-fucosylation of CPN20 by SPY fine-tunes ABA signaling in Arabidopsis.

scholarly journals The Arabidopsis spliceosomal protein SmEb modulates ABA responses by maintaining proper alternative splicing of HAB1

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yechun Hong ◽  
Juanjuan Yao ◽  
Huazhong Shi ◽  
Yunjuan Chen ◽  
Jian-Kang Zhu ◽  
...  
Keyword(s):  
Alternative Splicing ◽  
Seed Germination ◽  
Stress Responses ◽  
Core Protein ◽  
Aba Signaling ◽  
Terrestrial Plants ◽  
Spliceosomal Protein ◽  
Early Seedling ◽  
Early Seedling Development ◽  
Aba Hypersensitivity

AbstractAbscisic acid (ABA) signaling is critical for seed germination and abiotic stress responses in terrestrial plants. Pre-mRNA splicing is known to regulate ABA signaling. However, the involvement of canonical spliceosomal components in regulating ABA signaling is poorly understood. Here, we show that the spliceosome component Sm core protein SmEb plays an important role in ABA signaling. SmEb expression is up-regulated by ABA treatment, and analysis of Arabidopsis smeb mutant plants suggest that SmEb modulates the alternative splicing of the ABA signaling component HAB1 by enhancing the HAB1.1 splicing variant while repressing HAB1.2. Overexpression of HAB1.1 but not HAB1.2 rescues the ABA-hypersensitive phenotype of smeb mutants. Mutations in the transcription factor ABI3, 4, or 5 also reduce the ABA hypersensitivity of smeb mutants during seed germination. Our results show that the spliceosomal component SmEb plays an important role in ABA regulation of seed germination and early seedling development.

scholarly journals Light and abscisic acid interplay in early seedling development

2020 ◽  
Vol 229 (2) ◽  
pp. 763-769
Author(s):  
Premachandran Yadukrishnan ◽  
Sourav Datta
Keyword(s):  
Abscisic Acid ◽  
Seedling Development ◽  
Early Seedling ◽  
Early Seedling Development

scholarly journals Initiation and amplification of SnRK2 activation in abscisic acid signaling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhen Lin ◽  
Yuan Li ◽  
Yubei Wang ◽  
Xiaolei Liu ◽  
Liang Ma ◽  
...  
Keyword(s):  
Abscisic Acid ◽  
Higher Plants ◽  
Plant Responses ◽  
Activation Loop ◽  
Aba Signaling ◽  
Kinase Activation ◽  
Abscisic Acid Signaling ◽  
Aba Receptor ◽  
Amplification Mechanism

AbstractThe phytohormone abscisic acid (ABA) is crucial for plant responses to environmental challenges. The SNF1-regulated protein kinase 2s (SnRK2s) are key components in ABA-receptor coupled core signaling, and are rapidly phosphorylated and activated by ABA. Recent studies have suggested that Raf-like protein kinases (RAFs) participate in ABA-triggered SnRK2 activation. In vitro kinase assays also suggest the existence of autophosphorylation of SnRK2s. Thus, how SnRK2 kinases are quickly activated during ABA signaling still needs to be clarified. Here, we show that both B2 and B3 RAFs directly phosphorylate SnRK2.6 in the kinase activation loop. This transphosphorylation by RAFs is essential for SnRK2 activation. The activated SnRK2s then intermolecularly trans-phosphorylate other SnRK2s that are not yet activated to amplify the response. High-order Arabidopsis mutants lacking multiple B2 and B3 RAFs show ABA hyposensitivity. Our findings reveal a unique initiation and amplification mechanism of SnRK2 activation in ABA signaling in higher plants.

scholarly journals The Arabidopsis thaliana E3 Ubiquitin Ligase BRIZ Functions in Abscisic Acid Response

2021 ◽  
Vol 12 ◽  
Author(s):  
Katrina J. Linden ◽  
Mon Mandy Hsia ◽  
Yi-Tze Chen ◽  
Judy Callis
Keyword(s):  
Arabidopsis Thaliana ◽  
Abscisic Acid ◽  
E3 Ligase ◽  
Normal Growth ◽  
Growth Conditions ◽  
Aba Signaling ◽  
Wild Type ◽  
Ubiquitin System ◽  
Early Seedling ◽  
Cotyledon Expansion

The ubiquitin system is essential for multiple hormone signaling pathways in plants. Here, we show that the Arabidopsis thaliana E3 ligase BRIZ, a heteromeric ligase that consists minimally of BRIZ1 and BRIZ2 proteins, functions in abscisic acid (ABA) signaling or response. briz1 and briz2 homozygous mutants either fail to germinate or emerge later than wild-type seedlings, with little cotyledon expansion or root elongation and no visible greening. Viability staining indicates that briz1 and briz2 embryos are alive but growth-arrested. Germination of briz mutants is improved by addition of the carotenoid biosynthetic inhibitor fluridone or gibberellic acid (GA3), and briz mutants have improved development in backgrounds deficient in ABA synthesis (gin1-3/aba2) or signaling (abi5-7). Endogenous ABA is not higher in briz2 seeds compared to wild-type seeds, and exogenous ABA does not affect BRIZ mRNAs in imbibed seeds. These results indicate that briz embryos are hypersensitive to ABA and that under normal growth conditions, BRIZ acts to suppress ABA signaling or response. ABA signaling and sugar signaling are linked, and we found that briz1 and briz2 mutants excised from seed coats are hypersensitive to sucrose. Although briz single mutants do not grow to maturity, we were able to generate mature briz2-3 abi5-7 double mutant plants that produced seeds. These seeds are more sensitive to exogenous sugar and are larger than seeds from sibling abi5-7 BRIZ2/briz2-3 plants, suggesting that BRIZ has a parental effect on seed development. From these data, we propose a model in which the BRIZ E3 ligase suppresses ABA responses during seed maturation and germination and early seedling establishment.

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