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Wang J, Sun N, Zheng L, Zhang F, Xiang M, Chen H, Deng XW, Wei N. Brassinosteroids promote etiolated apical structures in darkness by amplifying the ethylene response via the EBF-EIN3/PIF3 circuit. THE PLANT CELL 2023; 35:390-408. [PMID: 36321994 PMCID: PMC9806594 DOI: 10.1093/plcell/koac316] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Germinated plants grow in darkness until they emerge above the soil. To help the seedling penetrate the soil, most dicot seedlings develop an etiolated apical structure consisting of an apical hook and folded, unexpanded cotyledons atop a rapidly elongating hypocotyl. Brassinosteroids (BRs) are necessary for etiolated apical development, but their precise role and mechanisms remain unclear. Arabidopsis thaliana SMALL AUXIN UP RNA17 (SAUR17) is an apical-organ-specific regulator that promotes production of an apical hook and closed cotyledons. In darkness, ethylene and BRs stimulate SAUR17 expression by transcription factor complexes containing PHYTOCHROME-INTERACTING FACTORs (PIFs), ETHYLENE INSENSITIVE 3 (EIN3), and its homolog EIN3-LIKE 1 (EIL1), and BRASSINAZOLE RESISTANT1 (BZR1). BZR1 requires EIN3 and PIFs for enhanced DNA-binding and transcriptional activation of the SAUR17 promoter; while EIN3, PIF3, and PIF4 stability depends on BR signaling. BZR1 transcriptionally downregulates EIN3-BINDING F-BOX 1 and 2 (EBF1 and EBF2), which encode ubiquitin ligases mediating EIN3 and PIF3 protein degradation. By modulating the EBF-EIN3/PIF protein-stability circuit, BRs induce EIN3 and PIF3 accumulation, which underlies BR-responsive expression of SAUR17 and HOOKLESS1 and ultimately apical hook development. We suggest that in the etiolated development of apical structures, BRs primarily modulate plant sensitivity to darkness and ethylene.
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Affiliation(s)
- Jiajun Wang
- School of Life Sciences, Southwest University, Chongqing 400715, China
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Ning Sun
- Key Laboratory of Growth Regulation and Transformation Research of Zhejiang Province, School of Life Sciences, Westlake University, 18 Shilongshan Road, Hangzhou 310024, China
| | - Lidan Zheng
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Fangfang Zhang
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Mengda Xiang
- School of Life Sciences, Southwest University, Chongqing 400715, China
| | - Haodong Chen
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Xing Wang Deng
- State Key Laboratory of Protein and Plant Gene Research, School of Advanced Agricultural Sciences and Life Sciences, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Institute of Plant and Food Science, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China
| | - Ning Wei
- School of Life Sciences, Southwest University, Chongqing 400715, China
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MdPP2C24/37, Protein Phosphatase Type 2Cs from Apple, Interact with MdPYL2/12 to Negatively Regulate ABA Signaling in Transgenic Arabidopsis. Int J Mol Sci 2022; 23:ijms232214375. [PMID: 36430851 PMCID: PMC9696740 DOI: 10.3390/ijms232214375] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/22/2022] Open
Abstract
The phytohormone abscisic acid (ABA) plays an important role in the ability of plants to cope with drought stress. As core members of the ABA signaling pathway, protein phosphatase type 2Cs (PP2Cs) have been reported in many species. However, the functions of MdPP2Cs in apple (Malus domestica) are unclear. In this study, we identified two PP2C-encoding genes, MdPP2C24/37, with conserved PP2C catalytic domains, using sequence alignment. The nucleus-located MdPP2C24/37 genes were induced by ABA or mannitol in apple. Genetic analysis revealed that overexpression of MdPP2C24/37 in Arabidopsis thaliana led to plant insensitivity to ABA or mannitol treatment, in terms of inhibiting seed germination and overall seedling establishment. The expression of stress marker genes was upregulated in MdPP2C24/37 transgenic lines. At the same time, MdPP2C24/37 transgenic lines displayed inhibited ABA-mediated stomatal closure, which led to higher water loss rates. Moreover, when exposed to drought stress, chlorophyll levels decreased and MDA and H2O2 levels accumulated in the MdPP2C24/37 transgenic lines. Further, MdPP2C24/37 interacted with MdPYL2/12 in vitro and vivo. The results indicate that MdPP2C24/37 act as negative regulators in response to ABA-mediated drought resistance.
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