摘要
As sessile organisms, plants encounter a variety of environmental stresses and must optimize their growth for survival. Abscisic acid （ABA） and cytokinin antagonistically regulate many developmental processes and environmental stress responses in plants. However, the molecular mechanism underlying this antag- onism remains poorly defined. In this study, we demonstrated that Sucrose nonfermentingl-related kinases SnRK2.2, SnRK2.3, and SnRK2.6, the key kinases of the ABA signaling pathway, directly interact with and phosphorylate type-A response regulator 5 （ARR5）, a negative regulator of cytokinin signaling. The phosphorylation of ARR5 Ser residues by SnRK2s enhanced ARR5 protein stability. Accord- ingly, plants overexpressing ARR5 showed ABA hypersensitivity and drought tolerance, and these pheno- types could not be recapitulated by overexpressing a non-phosphorylated ARR5 mimic. Moreover, the type-B ARRs, ARR1, ARR11 and ARR12, physically interacted with SnRK2s and repressed the kinase activ- ity of SnRK2.6. The arrl, 11,12 triple mutant exhibited hypersensitivity to ABA. Genetic analysis demon- strated that SnRK2s act upstream of ARR5 but downstream of ARR1, ARR11 and ARR12 in mediating ABA response and drought tolerance. Taken together, this study unravels the antagonistic actions of several molecular components of the ABA and cytokinin signaling pathways in mediates drought stress response, providing significant insights into how plants coordinate growth and drought stress response by integrating multiple hormone pathways.
As sessile organisms, plants encounter a variety of environmental stresses and must optimize their growth for survival. Abscisic acid （ABA） and cytokinin antagonistically regulate many developmental processes and environmental stress responses in plants. However, the molecular mechanism underlying this antag- onism remains poorly defined. In this study, we demonstrated that Sucrose nonfermentingl-related kinases SnRK2.2, SnRK2.3, and SnRK2.6, the key kinases of the ABA signaling pathway, directly interact with and phosphorylate type-A response regulator 5 （ARR5）, a negative regulator of cytokinin signaling. The phosphorylation of ARR5 Ser residues by SnRK2s enhanced ARR5 protein stability. Accord- ingly, plants overexpressing ARR5 showed ABA hypersensitivity and drought tolerance, and these pheno- types could not be recapitulated by overexpressing a non-phosphorylated ARR5 mimic. Moreover, the type-B ARRs, ARR1, ARR11 and ARR12, physically interacted with SnRK2s and repressed the kinase activ- ity of SnRK2.6. The arrl, 11,12 triple mutant exhibited hypersensitivity to ABA. Genetic analysis demon- strated that SnRK2s act upstream of ARR5 but downstream of ARR1, ARR11 and ARR12 in mediating ABA response and drought tolerance. Taken together, this study unravels the antagonistic actions of several molecular components of the ABA and cytokinin signaling pathways in mediates drought stress response, providing significant insights into how plants coordinate growth and drought stress response by integrating multiple hormone pathways.
作者
Xiaozhen Huang
Lingyan Hou
Jingjing Meng
Huiwen You
Zhen Li
Zhizhong Gong
Shuhua Yang
Yiting Shi
Xiaozhen Huang;Lingyan Hou;Jingjing Meng;Huiwen You;Zhen Li;Zhizhong Gong;Shuhua Yang(State Key Laboratory of Plant Physiology and Biochemistry,College of Biological Sciences,China Agricultural University,Beijing 100193,China;School of Pharmaceutical Sciences,Capital Medical University,Beijing 100020,China ＊Correspondence： Yiting Shi（shiyiting@cau.edu.cn）https：//doi.org/10.1016/j.molp.2018.05.001)
