ZmCCaMK在BR增强作物耐旱性中的功能分析

In this proposal, the role and mechanisms of ZmCCaMK in BR-enhanced water stress tolerance will be investigated in maize. The role of ZmCCaMK in BR-induced antioxidant defense and further water stress tolerance will be studied first. Then proteins interact with ZmCCaMK, playing role in BR-enhanced water stress tolerance, will be screened and the mechanisms of protein-protein interaction will also be analyzed. The relationship between ZmCCaMK and its interacting proteins, and ABA, Ca2+/CaM, H2O2 will be determined. Whether ZmCCaMK and its interacting proteins play roles in H2O2 self-propagation, and if so, what the relationship between ZmCCaMK and its interacting proteins, and ZmMPK5 is will also be studied. The objective of this study is to elucidate the function of ZmCCaMK in BR-enhanced water stress tolerance in maize. The proposal is not only helpful to our understanding for the mechanism of BR-induced antioxidant leading to water stress tolerance, but also has an important significance for improvement of crop water stress resistance by using molecular biology manipulation.

本项目拟在前期工作的基础上，以玉米为材料，研究ZmCCaMK在BR增强作物耐旱性中的作用及机理。拟调查ZmCCaMK在BR诱导的抗氧化防护进而增强作物耐旱性过程中的作用，鉴定与其相互作用的靶蛋白及其互做机制，明确BR诱导的ZmCCaMK及其靶蛋白与ABA、Ca2+/CaM、H2O2自我放大及ZmMPK5的关系，阐明BR诱导的ZmCCaMK与BR诱导的抗氧化防护以及BR增强作物耐旱性的关系。预期研究结果可以深入认识BR诱导的抗氧化防护及其增强作物耐旱性的机制，为利用分子生物学手段提高作物耐旱性提供重要的理论基础。

植物激素油菜素内酯（brassinosteroid, BR）在植物对干旱等非生物胁迫抗性方面起重要作用。申请人实验室前面的研究显示，干旱胁迫条件下，植物体中积累的内源BR能减轻干旱胁迫导致的玉米幼苗氧化损伤，进一步研究显示BR通过促进另一种植物激素脱落酸（abscisic acid, ABA）的合成增加来增强BR对干旱胁迫的耐性，然而，BR缓解氧化损伤从而增强植物耐旱性的详细机理是什么？这些我们都还不清楚，要回答这些问题需要进一步鉴别这一过程中的新成员。通过研究，我们发现了ZmCCaMK参与BR诱导的抗氧化防护过程，并与Ca2+/CaM之间存在相互影响，通过调控NADPH氧化酶基因的表达参与BR诱导的H2O2自我放大。同时ZmCCaMK也参与ABA诱导的抗氧化防护过程，通过酵母双杂交筛选到一个与其相互作用蛋白----ZmNAC84，并进一步发现ZmCCaMK通过磷酸化ZmNAC84的113位丝氨酸而参与此过程，最终缓解干旱导致的氧化损伤、增强植物耐旱性。此外本项目还发现ABA通过MAP65-1a影响BR诱导的抗氧化防护，ZmMPK5影响MAP65-1a的表达，但ZmCCaMK不影响MAP65-1a的表达。RbohI在植物对干旱胁迫的响应中发挥积极作用。目前，共发表标注本项目资助的文章4篇，另有数据还在整理中，后面还会有高质量文章发表。