水稻钙依赖蛋白激酶OsCDPK24在抗冷中的作用与机理研究

Calcium-dependent protein kinases (CDPKs) comprise a larger family of Ser/Thr kinases in plants and play an important role in plant Ca2+ signal transduction. Previous studies have demonstrated that most CDPKs were involved in regulating plants responses to drought, salt, chilling temperatures and diseases stresses. However, those factors that affect CDPKs expression and kinase activity, and substrates of CDPKs remain unknown. Until now, none of signal transduction networks that with CDPKs centered has been characterized. Our recent studies showed that OsCDPK24 gene is a member of the rice CDPKs family that response to cold stress. Overexpression lines significantly exhibited enhanced resistance to chilling temperature, and dsRNAi lines exhibited reduced resistance to cold stress. These proved that OsCDPK24 positively regulate rice responses to cold stress. In this work, we aim to study the mechanism of OsCDPK24 in modulating rice responses to cold stress, consisting of the analysis of gene expression regulation, kinase activity, protein subcellular localization and its substrates, and provide a theoretical basis for the cultivation of rice varieties resistance to cold.

钙依赖蛋白激酶（CDPKs）是植物中广泛存在的一大类依赖Ca2+激活的Ser/Thr蛋白激酶，在植物的Ca2+信号转导途径中发挥重要调节作用。虽已了解CDPKs在植物抵御干旱、高盐、冷和病原菌等不利环境中起到重要调控作用，然而它们如何受调节表达，又通过那些底物将信号传递下去，还知之甚少。我们的前期研究表明，OsCDPK24是水稻CDPKs家族成员中受冷胁迫响应的基因之一，过量表达能有效增强水稻对低温的抵抗能力，抑制表达使水稻对冷更敏感，说明它正向参与调控水稻抗冷反应。本课题旨在研究OsCDPK24表达调控、激酶活性调节、蛋白定位及作用底物，综合分析以OsCDPK24为中心参与的抗冷信号调控网络，为全面阐述OsCDPK24的抗冷作用机制以及培育抗冷品种水稻提供理论依据。

钙依赖蛋白激酶（CDPKs）是一类丝氨酸/苏氨酸蛋白激酶在植物逆境响应中起作用。本项目，我们研究了水稻OsCDPK24提高水稻耐冷性的分子机制。研究结果显示，OsCDPK24在多个水稻品种中受低温诱导，OsCDPK24过量表达可提高水稻的耐冷性，而降低其表达则增加了水稻的冷敏感性。OsCDPK24正向调控渗透调节物质脯氨酸和抗氧化物质谷胱甘肽的积累。在低温条件下，过表达材料中OsCDPK24能够维持GSH/GSSG在较高比率。我们的结果显示，谷胱甘肽依赖的巯基转移酶OsGrx10是OsCDPK24的一个底物。OsGrx10与OsCDPK24的激酶结构域互作，并被磷酸化。钙离子可调控OsCDPK24对OsGrx10的磷酸化作用。这些结果表明，OsCDPK24作为正调控因子可能通过磷酸化抑制OsGrx10的活性维持更高的谷胱甘肽水平来参与水稻冷逆境耐受。本项目的结果为提高水稻耐冷性状提供候选基因参考。