Two E-clade protein phosphatase 2Cs enhance ABA signaling by dephosphorylating ABI1 in Arabidopsis

文献类型： 外文期刊

第一作者： Zhang, Ya

作者： Zhang, Ya;Han, Liyuan;Liu, Junjie;Chang, Miao;Li, Chuanling;Shang, Jian-Xiu;Tang, Wenqiang;Sun, Yu;Deng, Zhiping;Li, Chuanling

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关键词： abscisic acid signaling; ABI1; E-clade protein phosphatase 2C; dephosphorylation; ABA response

期刊名称：MOLECULAR PLANT （ 影响因子：24.1； 五年影响因子：25.8 ）

ISSN： 1674-2052

年卷期： 2025 年 18 卷 5 期

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收录情况： SCI

摘要： ABA INSENSITIVE 1 (ABI1) and ABI2 are co-receptors of the phytohormone abscisic acid (ABA). Studies have demonstrated that phosphorylation of multiple amino acids on ABI1/2 augments their ability to inhibit ABA signaling in planta. However, whether and how the dephosphorylation of ABI1/2 is regulated to enhance plant sensitivity to ABA remain unknown. In this study, we identified two protein phosphatases, designated ABI1-Dephosphorylating E-clade PP2C 1 (ADEP1) and ADEP2, that interact with ABI1/2. Mutants lacking ADEP1, ADEP2, or both (adep1/2) exhibited reduced ABA inhibition of seed germination and root growth, as well as lower levels of ABA-induced stomatal closure. In addition, ABA-induced accumulation of ABI5 protein and expression of downstream target genes are reduced in the adep1/2 mutant compared with the wild type. These findings suggest that ADEP1/2 function as positive regulators of the ABA signaling pathway. Mass spectrometry analysis and two-dimensional electrophoresis identified Ser117 as a major ABA-induced phosphorylation site on the ABI1 protein. ADEP1/2 can dephosphorylate Ser117, leading to destabilization of the ABI1 protein and increased sensitivity of plants to ABA. Moreover, ABA treatment decreases the abundance of ADEP1/2 proteins. In summary, our study reveals two novel regulatory proteins that modulate ABA signaling and provides new insights into the regulatory network that fine-tunes plant ABA responses.

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