油菜素甾醇（BR）在植物生长发育的各个进程都发挥着重要作用，其路径是分子育种的主要目标路径之一。马铃薯是我国重要的粮食及蔬菜兼用作物，块茎是其最重要的产品器官，其生长发育直接影响薯块的产量和品质。研究表明，BR信号在马铃薯块茎形成过程中起着重要调控作用，然而其调控块茎形成的分子机理尚不明确。申请人在筛选受体激酶StBRI1的互作蛋白时，发现了一个与StBRI1互作的质膜H+-ATPase PHA2，并证实了这一互作。初步研究表明，StBRI1-PHA2在马铃薯块茎形成过程中起着正向调控作用。基于此，本项目拟通过遗传转化、激酶分析和免疫共沉淀等方法，研究StBRI1和PHA2在块茎形成中的生物学功能，研究StBRI1与PHA2互作并通过磷酸化修饰调控PHA2活性的机制，揭示StBR11-PHA2调控块茎形成的分子机理。本研究将为利用基因工程手段提高马铃薯的产量和品质提供理论基础。

Brassinosteroids (BRs) play critical roles in regulating plant growth and development and BR signaling pathway is one of the major targets of molecular breeding. Potato is one of the most important food and vegetable crops in China. Tubers are the main products organs possessing significant economic value, whose growth and development directly affect the yield and quality. Previous studies have shown that BR signaling plays significant functions in tuber formation, but the molecular regulation mechanism is still unclear. Applicant found that StBRI1 interacts with plasma membrane H+-ATPase PHA2 in screening the interacting proteins of receptor kinase StBRI1. Preliminary biochemical and genetics data indicate that StBRI1 interacts with PHA2 in vivo and StBRI1-PHA2 function as positive regulators of tuberization. Based on the results above, through a series of methods, such as genetic transformation, in vitro kinase activity analysis, co-immunoprecipitation and so on, we aim to clarify the biological functions of StBRI1 and PHA2 in regulating potato tuberization, to uncover the detailed biochemical mechanism of StBRI1 on PHA2 phosphorylation level and activity regulation, and to reveal the mechanism of potato tuber formation regulated by interaction between StBRI1 and PHA2. This study is expect to provide a theoretical basis for improving yield and quality of potato by using genetic engineering techniques.