受体类激酶CWK1调控水稻纤维素合成的机制研究

Cellulose is a major component of plant cell wall and represents the most abundant nature resource with a great economic importance. Since cellulose abundance and property is also highly associated with multiple important agronomic traits and physiological processes, cellulose synthesis is under a tight control in plants. The proteomics analyses have revealed that many proteins involved in cellulose biosynthesis are phosphorylated and showed impacts on cellulose amount, indicating that phosphorylation is a common regulatory way in cellulose formation. However, the identified kinases that modulate cellulose synthesis are very limited. CWK1 is a putative receptor-like kinase required for cellulose synthesis as it is coexpressed with CESAs. In this study, we plan to characterize CWK1 functions via multidisciplinary approaches, aiming to: verify the coexpression profile of CWK1 and CESAs at cellular level; characterize the biochemical and biological roles of CWK1; identify phosphorylation targets of CWK1 through interacting protein screening and phosphorylation assays; and analyze the phosphorylation effects on cellulose synthesis. Finally, the regulatory pathways mediated by CWK1, as well as the biological functions, will be identified. This study may further understanding the elaborate regulatory pathways of cellulose synthesis control and genetically engineering of cellulose properties for the improvement of relevant agronomic traits in rice.

纤维素是植物细胞壁中最主要、且最具经济价值的成分。植物体中纤维素的合成水平与诸多重要农艺性状的形成和生理过程关系密切，因而受到严格调控。蛋白质组质谱分析发现参与纤维素合成的不少关键蛋白存在磷酸化修饰，并影响纤维素合成，表明磷酸化修饰是调控纤维素合成的一种重要方式。然而迄今为止鉴定到的参与纤维素合成的受体类激酶仍为数极少。CWK1是通过水稻转录组测序及共表达分析而筛选到的一个受体类激酶，且功能未知。本研究拟利用遗传学、生物化学、分子生物学等多学科手段，验证CWK1基因与纤维素合酶基因的共表达情况；分析CWK1的激酶活性，筛选其作用底物，解析CWK1调控纤维素合成的信号转导通路和遗传网络，揭示纤维素合成调控的分子机制；研究cwk1及其调控通路上相关突变体的表型，明确其生物学功能，为水稻等作物高产优质分子设计育种提供新的基因资源。

纤维素是植物次生细胞壁中最主要、且最具经济价值的成分。它不仅构成了承力网络结构，还是植物生长的重要体现。植物体中纤维素合成水平与诸多重要农艺性状、如抗倒伏性状的形成关系密切，其合成因此受到严格调控。受体激酶是感知传递信号的关键节点。然而迄今为止，鉴定的参与纤维素合成的类受体激酶仍为数极少。CSK1 (前期命名为CWK1)是通过水稻转录组测序及共表达分析而获得的一个功能未知受体类激酶。本研究通过遗传学、分子生物学、细胞生物学等手段，阐明了水稻CSK1负调控次生壁纤维素积累的分子机制和调控通路，包括鉴定了CSK1的磷酸化底物VND6，而水稻VND6是次生壁合成的重要开关；明确CSK1磷酸化VND6使其转录激活活性减缓；发现CSK1响应ABA、干旱等处理，ABL1可调控CSK1的表达。通过项目实施，明确CSK1可调控植株支撑力和耐逆性，是平衡支撑性与环境可塑性的重要节点，为水稻等作物分子设计育种提供新的基因资源。