Cao Pengfei, Zhou Lin, Du Mingwei, Tian Xiaoli, Li Fangjun, Li Zhaohu
State Key Laboratory of Plant Environmental Resilience, Engineering Research Center of Plant Growth Regulator, Ministry of Education & College of Agronomy and Biotechnology, China Agricultural University, Beijing, China.
Plant Biotechnol J. 2025 Sep;23(9):3561-3580. doi: 10.1111/pbi.70166. Epub 2025 Jun 8.
The post-translational phosphorylation modification of stress-related proteins regulated by kinases and phosphatases is one of the crucial regulatory mechanisms for plants in response to salt stress. However, the paired kinases and phosphatases of the same substrate that participate in response to salt tolerance in crops, especially in cotton, remain to be elucidated. Here, we identified GhTOPP4aD as a negative regulator of salt-stress response in cotton. GhTOPP4aD interacted with Raf-like kinase 36 (GhRAF36) and ABA Insensitive 1 (GhABI1) respectively, thereby inhibiting the phosphorylation activity of GhRAF36 and directly dephosphorylating GhABI1 to counteract GhRAF36 regulation. The phosphatase activity of GhABI1 was inhibited by GhRAF36-mediated phosphorylation at two unique residues Thr124 and Ser357 in cotton, whereas it was compromised by GhTOPP4aD. GhTOPP4aD thereby limited ABA signal transduction and orchestrated ABA-responsive gene expression. Together, modulation of the phosphorylation dynamics of GhABI1 by GhRAF36 kinase and GhTOPP4aD phosphatase constitutes an essential mechanism for ABA response and salt tolerance in cotton.
由激酶和磷酸酶调控的应激相关蛋白的翻译后磷酸化修饰是植物响应盐胁迫的关键调控机制之一。然而，参与作物尤其是棉花耐盐性响应的同一底物的配对激酶和磷酸酶仍有待阐明。在此，我们鉴定出GhTOPP4aD是棉花盐胁迫响应的负调控因子。GhTOPP4aD分别与类Raf激酶36（GhRAF36）和脱落酸不敏感蛋白1（GhABI1）相互作用，从而抑制GhRAF36的磷酸化活性并直接使GhABI1去磷酸化以抵消GhRAF36的调控作用。在棉花中，GhRAF36介导的对两个独特残基苏氨酸124和丝氨酸357的磷酸化抑制了GhABI1的磷酸酶活性，而GhTOPP4aD则使其受损。GhTOPP4aD从而限制了脱落酸信号转导并协调了脱落酸响应基因的表达。总之，GhRAF36激酶和GhTOPP4aD磷酸酶对GhABI1磷酸化动态的调节构成了棉花中脱落酸响应和耐盐性的重要机制。
