水稻PsbS1基因调控非光化学淬灭的机理研究

The photoprotective processes conferred by nonphotochemical quenching (NPQ) serve fundamental roles in maintaining plant fitness and sustainable yield. OsPsbS1 as a major determinant for natural variation of nonphotochemical quenching capacity in rice (Oryza sativa). The PsbS protein and the its expression is an important factor to control the production of NPQ and determine the whole NPQ capacity. So far, the reason for OsPsbS1 expression differ between indica group and japonica group remain unknown, the key cis-acting elements in the OsPsbS1 promoter region we didn't find it, and the trans-acting factors interacting with the OsPsbS1 has not been reported.Recently, by a series of truncated promoters assay, we have revealed that the promoter region was enhanced transcription elements. In this research proposal, we plan to find the key cis-acting elements of OsPsbS1 by designing a series of truncated and site-mutated promoters, identify the trans-acting factors which interact with promoter by various approaches, such as yeast one-hybrid assay, electrophoretic mobility shift assay, and chromatin immunoprecipitation. The research results will help elucidate underlying mechanism of nonphotochemical quenching variation in rice regulated by PsbS1 gene. The research results will help us understand in depth how PsbS1 functions and provide guidance for high photosynthetic efficiency breeding in rice.

非光化淬灭（NPQ）是一种光保护机制，它在维持植物健康生长发育过程中发挥着关键作用。主效QTL基因OsPsbS1在调控水稻NPQ容量中发挥着极其重要的功能，PsbS蛋白及其表达量是控制NPQ产生以及决定容量大小的重要因子。但长期以来关于籼粳之间OsPsbS1表达量差异原因及其关键顺式作用元件尚不清楚，与该基因互作的反式作用因子还鲜为人知。申请人前期利用启动子截短鉴定出PsbS1启动子区段有增强转录的顺式作用元件存在。本项目将以此为基础，进一步采用启动子截短及定点突变方法确定调控OsPsbS1表达量差异的关键顺式作用元件；采用酵母单杂、凝胶阻滞及染色质免疫共沉淀等技术鉴定与OsPsbS1直接互作的反式作用因子，以阐明OsPsbS1调控水稻NPQ容量的机制。本项目的研究对于深入理解OsPsbS1的功能及水稻高光效育种实践具有重要指导意义。

OsPsbS1基因在调控水稻NPQ容量中发挥了极其重要的作用，PsbS蛋白及其表达量是控制非光化淬灭产生以及决定qE及整个NPQ容量大小的重要因子。我们利用通过酵母单杂交文库筛选到一个与OsPsbS1启动子区互作的反式作用因子GHD7蛋白，并验证了这种相互作用，该转录因子的ChIP-Seq分析也证实了该转录因子能够富集与光合作用相关的基因。启动子区CRISPR/Cas9定向编辑结果显示不同区域的序列突变显示出了不同的NPQ值，mut1突变型（5’ -UTR区51 ~319处缺失） 269 bp碱基的缺失后引起NPQ值的急剧下降，而mut2突变型（5’ -UTR区42~93处缺失，同时5’ -UTR区319处1bp G碱基的缺失）52 bp碱基的缺失引起NPQ值出现了中等程度的下降，该突变型能够提升产量。转基因植株中发现Lhcb3基因通过下调PSII相关基因从而下调OsPsbS1基因的表达。该项目完成将加深对OsPsbS1调控水稻NPQ容量的分子机制的认识；应用上，通过CRISPR/Cas9基因编辑我们创造了5’ -UTR区缺失的优良突变体mut2，为水稻高光效育种实践提供坚实的理论和实践基础。