磷是一切生命所必需的大量元素之一。目前已报道参与磷饥饿信号调控网络的基因越来越多，但关于磷饥饿胁迫抑制植物生长的分子生理机制还很少。PHO80-PHO85复合体是酵母磷信号通路中重要负调控因子，同时还参与调控细胞周期中G0期的起始。OsCYCP是PHO80在水稻中的同源蛋白，我们发现其中OsCYCP1;1能部分回复pho80突变体磷信号，OsCYCP1;1能影响磷饥饿响应信号，但对植株的生长没有明显影响。前期的研究发现CYCP亚类成员CYCP4基因的表达受低磷诱导，初步结果表明CYCP4负调控水稻植株生长及磷信号。因此，本研究将通过系统分析CYCP4基因的表达模式，借助创制的过表达及功能缺失突变体解析其参与低磷信号及低磷胁迫下的植株生长的可能机制。同时，通过解析CYCP4的蛋白互作模式及其与磷信号关键调控因子的遗传关系，最终明确CYCP4参与低磷胁迫下水稻生长及磷信号途径的分子生理机制。

Inorganic phosphate is one of the most essential and limiting nutrients in all organisms. Up to now, a number of genes have been reported to participate in regulation of phosphate deficiency responses in plant. However, few were discovered to regulate the growth inhibition of plant during phosphate starvation. In the budding yeast, Saccharomyces cerevisiae, PHO80-PHO85 complex is involved both in regulating the phosphate signal transduction (PHO) pathway and in controlling the G0 entry. Previously, we identified and cloned seven PHO80 homologous genes named OsCYCPs in rice. Among them, only the OsCYCP1;1 gene was able to partially rescue the pho80 mutant strain of yeast. OsCYCP1;1 influences the phosphate starvation signaling response, but does not affect the growth and the development of rice. Our previous work has demonstrated that CYCP4, a membrane of the CYCP gene family, is regulated by phosphate deficiency through transcriptional regulation. Preliminary results have also shown that CYCP4 negatively regulates plant growth and phosphate signaling. Hence, by analyzing the expression pattern of CYCP4 and studying both CYCP4 over-expressing and plants, we aim to characterize the possible mechanism of CYCP4 in growth regulation during phosphate deficiency. Furthermore, by identifying it physical and genetic interacting partners, we want to eventually uncover the detailed molecular mechanism of CYCP4 in regulating plant growth and phosphate signaling during phosphate deficiency.