叶绿体质子梯度调控蛋白基因PGR5敲除会导致拟南芥在波动光下致死，但其作用机理尚有待于阐明。我们筛选到两个对波动光敏感的拟南芥突变体fluc1,fluc2，分离鉴定到两个定位在叶绿体的新功能基因Fluc1 和Fluc2，两个基因之间没有同源性。Fluc1突变导致依赖叶绿体NAD（P）H脱氢酶（NDH）循环电子传递活性的显著降低，但不影响非循环电子传递活性，另外发现Fluc1与参与NDH组装的CRR6蛋白互作。而Fluc2与PGR5互作，Fluc2突变反而促进PGR5的活性，但显著降低了跨类囊体膜质子梯度建立的速度。本项目拟利用分子遗传学和生化方法，研究Fluc1和Fluc2对NDH、PGR5等叶绿体基因的调控作用，寻找到参与这些调控途径的其它互作蛋白，结合生物信息学等手段，深入研究Fluc1和Fluc2在波动光下对光合作用的调控，以期阐明植物应对波动光胁迫的防御机制。

The knocking out of PGR5 gene encoded a chloroplast gradient regulatory protein would lead to lethal phenotype in Arabidopsis thaliana fluctuating light, but its mechanism remains to be elucidated. We screened two Arabidopsis mutants, fluc1 and fluc2 sensitive to fluctuating lights. And we isolated and identified two new functional genes Fluc1 and Fluc2 located in chloroplasts. There was no homology between the two genes. Mutation of Fluc1 resulted in a significant decrease in the activity of cyclic electron flow via chloroplast NAD (P) H dehydrogenase (NDH), but did not affect the linear electron flow. In addition, we found that the interaction between Fluc1 and CRR6 protein involved in assembly of NDH complex. Mutation of Fluc2 promoted the activity of PGR5, but evidently lowered the rate of the building-up proton gradient across thylakoid membranes. In this project, we plan to study the regulation of Fluc1 and Fluc2 on NDH, PGR5 and other chloroplast genes by molecular genetics and biochemical methods, and to find other interacting proteins involved in these regulatory pathways. Combining with bioinformatics and other means, we will further study the regulation of Fluc1 and Fluc2 on photosynthesis under fluctuating light in order to elucidate the defense mechanism of plants against fluctuating light stress.