C4光合结构形成的分子机制研究

Eleocharis vivipara is a freshwater amphibious plant. Under submerged condition, it forms the C3 photosynthetic structure and takes the way of C3 photosynthesis mode. In terrestrial condition, it forms the C4 photosynthetic structure and uses C4 photosynthesis mode. Adding a certain amount of ABA in the water, its photosynthetic structure and photosynthesis mode can convert into the C4 type. These characteristics provide the ideal opportunity to study C3 and C4 photosynthetic conversion mechanism and the molecular basis of C4 photosynthetic architecture formation. Based on the establishment of aquatic and terrestrial SSH library, together with the comparative transcriptome data from aquatic, terrestrial and ABA-induced samples, in this study we will first select the candidate genes which might be the C4 structure formation-related genes. By building their dsRNA and amiRNA vectors and using Eleocharis vivipara transformation system, we want to investigate the change of C4 photosynthesis mode under terrestrial condition. Meanwhile, those candidate genes that are effective for the change of C4 photosynthesis mode will be analyzed in yeast two-hybrid system by screening the aquatic and terrestrial yeast two-hybrid library. The identified interacting proteins will then be verified by the other methods. Our study has great value in understanding the gene regulatory networks of the C4 architecture formation.

大莎草系水陆两栖植物。其在水生条件下，形成C3光合结构和采用C3光合作用模式；而在陆生条件下，形成C4光合结构和采用C4光合作用模式；并且在水中添加一定量的ABA，其光合结构和光合作用方式可以转换为C4类型。这些特性为系统研究C3与C4光合机制转换以及C4光合结构形成的分子基础提供了极好的条件。本研究在建立的水生与陆生SSH文库，水生、陆生与水生ABA处理的转录组比较测序的基础上，挑选可能与C4结构形成相关的候选基因，分别构建dsRNA和amiRNA载体转化大莎草，考查转基因植株陆生状态下的C4光合作用模式的变化；对有效应的基因构建酵母双杂交载体，筛选水生与陆生酵母双杂文库，筛选出互作蛋白并进行验证，探求C4结构形成的基因调控网络。

对C3作物进行C4改良是提高C3作物产量的潜在策略之一。大莎草是两栖类水草，其水生为C3-C4型，陆生为C4型且其C4光合作用可以受ABA诱导。本项目执行期间对大莎草光合作用特性进行深入分析，比较分析不同条件下转录组和对大莎草进行基因组初步测序，综合解析其潜在的C4发育调控机制；以狐尾草为材料构建EMS突变体库，筛选C4结构变异突变体；同时对水稻內源CA1在光合作用和二氧化碳响应过程中的生物学功能进行研究。项目研究结果为深入解释C4光合作用调控和水稻光合作用改良提供理论依据和材料积累。