干旱胁迫是植物面临的最主要非生物胁迫之一，严重制约了农业生产。微丝骨架以其动态特性的变化调节气孔运动，参与干旱胁迫。我们已发表的工作表明，拟南芥酪蛋白激酶CKL2磷酸化微丝解聚因子ADF，调节微丝动态，调控气孔运动，在干旱胁迫响应中发挥重要功能，但目前关于CKL2调节蛋白的研究并不多。本项目的前期工作中，我们通过酵母双杂交，筛选到一个与CKL2相互作用的蛋白磷酸酶SMAP1。本课题拟运用生物化学，遗传学，细胞生物学等多种方法揭示SMAP1与CKL2互作，调节CKL2对ADF的磷酸化，影响微丝骨架动态，导致气孔运动改变的分子机理。阐明该磷酸化级联途径有助于进一步探索干旱胁迫信号转导路径，为抗旱农作物新品种培育提供理论指导。

Drought stress is one of the major abiotic stresses for plants which results in seriously damage to agriculture. Actin cytoskeleton plays an important role in regulating stomatal movement through continuous dynamic changes. Actin dynamics functions in drought stress responses. Our previous work showed that CKL2 regulates actin dynamics through phosphorylating and inhibiting actin depolymerizing factor ADF. CKL2 is involved in stomatal movement and has significant functions in drought stress responses. So far, how CKL2 is regulated remains largely unknown. In our preliminary study, we identified a phosphatase, SMAP1, as one of CKL2 interaction partners through yeast two-hybrid screening. In this study, we propose to illustrate the molecular mechanism underlying how CKL2 is regulated by SMAP1 by applying biochemical, genetic, and cell biological methods. Furthermore, we will investigate whether SMAP1 is involved in actin reorganization during stomatal closure through inhibiting the protein kinase activity of CKL2 on ADF4. By tackle of the SMAP1 mediated CKL2 phosphorylation cascade, it will contribute to a better understanding of the signal transduction pathway in response to drought stress and will therefore provide a theoretical basis for drought-resistant breeding development.