OsYODA1作为受体激酶DRUS1下游信号组分参与水稻花序发育调控的分子机制研究

The inflorescence morphogenesis is the crucial determinant for grains formation and yield potential in rice. So far, the essential roles of receptor-like kinases in mediating transmembrane signal transduction to control the inflorescence development has been rarely reported. Recently, we have reported that two receptor-like kinases DRUS1 and DRUS2 redundantly control the reproduction development in rice. They promote the inflorescence morphogenesis by activating the inflorescence meristem viability. To elucidate the DRUS1-mediated signal pathway in the inflorescence development, we have identified a putative DRUS1-interacting protein, OsYODA1, a mitogen-activated protein kinase (MAPKKK), using co-immunoprecipitation combined with mass spectrometry analysis. Their interaction had been confirmed by yeast-two-hybrid assay. In this project, we will study the roles of OsYODA1 in the inflorescence and uncover a MAPKKK phosphorylation cascade module and its downstream target gene. We will investigate the molecular mechanism of OsYODA1, as a DRUS1 downstream signaling component in the regulation of inflorescence development.

花序的形态建成对水稻产量形成至关重要，目前人们对类受体激酶介导的跨膜信号转导在花序发育调控中的作用研究得很少。我们最近报道了两个类受体激酶DRUS1和DRUS2功能冗余地调控水稻生殖发育过程，它们通过调控花序分生组织的活力影响花序的形态建成。然而，DRUS1调控花序发育的信号通路并不清楚。我们前期通过免疫共沉淀结合质谱测序技术以及酵母双杂交的初步验证，发现了DRUS1的候选互作蛋白OsYODA1，一个丝裂原活化蛋白激酶（MAPKKK）。本项目将通过一系列遗传和生化手段，研究OsYODA1在DRUS1介导的调控花序发育信号通路中的作用，并确定OsYODA1的信号级联磷酸化元件及下游调控靶基因，以期解析OsYODA1作为DRUS1介导的跨膜信号通路下游组分参与调控花序发育的分子机制。

花序的形态建成直接影响水稻产量。实验室前期发现两个CrRLK1L类受体激酶DRUS1和DRUS2功能冗余地调控水稻花序的形态建成。本项目通过免疫共沉淀联合质谱（IP-MS）技术筛选与DRUS1直接或者间接互作的蛋白，发现一个丝裂原活化蛋白激酶激酶激酶（OsMAPKKK），进化树分析发现它是拟南芥YODA的直系同源蛋白，被命名为OsYODA1，与YODA和OsYODA1在同一个分支上的OsMAPKKK被命名为OsYODA2。酵母双杂交和Overlay实验证明OsYODA1和DRUS1可以发生互作。表达模式分析发现OsYODA1和OsYODA2遍在表达，亚细胞定位分析表明OsYODA1定位在细胞质中，且定位不受DRUS1和DRUS2缺失的影响。遗传学研究发现OsYODA1和OsYODA2功能冗余地调控株高，花序长度，种子大小和结实率等多个生物学过程，而且OsYODA1起主导作用。根据遗传学表型分析，我们推测OsYODA1&2可以与DRUS1&2共同调控水稻的株高和花序长度，与另一个受体激酶UNK1跳调控种子大小。也就是说，在不同的生长发育背景下，OsYODA1和OsYODA2可能和不同的类受体激酶协同调控细胞伸张和细胞分裂。