钙/钙调素依赖型蛋白激酶（CCaMK）已经被证实是脱落酸（ABA）诱导的抗氧化防护信号转导中的重要组分，增强植物对水分胁迫、氧化胁迫的耐性，且在这一过程中，促分裂原活化蛋白激酶（MAPK）作用于CCaMK的下游。然而，ABA信号转导中CCaMK是怎样调节MAPK活化的机制仍有待阐明。本项目拟在前期工作的基础上，进一步鉴定ABA作用下水稻叶片中CCaMK OsDMI3与MAPKKs OsMKK1、OsMKK6之间的互作关系，在体内外澄清OsMKK1、OsMKK6是OsDMI3磷酸化的底物，阐明其磷酸化位点，进而分析OsDMI3介导的OsMKK1、OsMKK6磷酸化在ABA诱导的OsMPKs活化中的作用以及在ABA调控的生理反应中的作用。这一研究的开展不仅有助于人们对植物CCaMK参与ABA信号转导以及植物抗逆反应的作用机制的认识，而且对于利用分子生物学手段提高作物的耐逆性具有重要的指导意义。

It has been shown that Ca2+/calmodulin (CaM)-dependent protein kinase (CCaMK) is required for abscisic acid (ABA)-induced antioxidant defense and for the tolerance of plants to water stress and oxidative stress. There exists a cross-talk between CCaMK and mitogen-activated protein kinase (MAPK) in ABA signaling, in which CCaMK functions upstream of MAPK to regulate the antioxidant defense systems in plants. However, the mechanisms how CCaMK induces the activation of MAPK in ABA signaling remain to be determined. In this project, based on our previous studies for this project, we intend to identify the interaction between the rice CCaMK OsDMI3 and the rice MAPK kinases (MAPKKs) OsMKK1 and OsMKK6 and to clarify whether OsMKK1 and OsMKK6 are the phosphorylated substrates of OsDMI3 in vitro and in vivo. The phosphorylation sites of OsMKK1 and OsMKK6 by OsDMI3 are also determined. Further, we want to elucidate the roles of OsDMI3-mediated phosphorylation of OsMKK1 and OsMKK6 in ABA-induced activation of OsMPKs and in ABA-regulated physiological responses in rice. This project is not only helpful to our understanding for the mechanisms how CCaMK is involved in ABA signaling and in plant response to water stress and oxidative stress, but also has an important significance for improvement of crop stress resistance by using molecular biology manipulation.