抽穗期是决定水稻产量和种植区域的一个重要农艺性状。鉴定和解析抽穗期相关基因及其调控网络，对于培育水稻品种具有重要意义。本申请前期研究发现了一个新的水稻开花抑制基因SOF（Suppressor of Flowering），SOF过量表达材料晚花，sof突变体早花。SOF蛋白定位于细胞核，具有转录激活活性和DNA结合能力。进一步发现抽穗期抑制因子Hd2在SOF-OE中表达量显著升高，推测SOF通过提高Hd2的表达延迟水稻开花，初步利用体外实验证实SOF能结合Hd2启动子元件。为深入解析SOF调控开花的分子机制，本申请拟结合多种分子生物学手段，在植物体内研究SOF与Hd2的调控关系；利用双突变体研究SOF与Hd2在遗传学上的关系。本项目预期不仅鉴定新的水稻开花抑制因子SOF，还将揭示SOF调控水稻抽穗期的分子机理，项目研究成果将为完善水稻抽穗期关系网络奠定理论基础，为分子育种提供理论指导。

Rice flowering time is one of the most important agronomic traits determining rice yield and regional adaptability. Identifying and characterizing novel flowering time genes is of great significance for the breeding high-yield rice cultivars. .In our previous study, a novel flowering regulating gene SOF (Suppressor of Flowering) was identified, SOF overexpression lines showed later flowering, whereas sof mutant flowered earlier, compared to wild type. SOF is a nucleus localized protein, and exhibits transcriptional activation activity and DNA binding activity. Interestingly, we found that expression of Hd2, a key flowering suppressor, is increased significantly in SOF-OE. Further experiments showed that SOF indeed binds to the promoter region of Hd2 gene. We thus speculate that SOF might delay flowering through promoting the Hd2 expression. .In this proposal, multiple discipline techniques (including genetics, biochemistry, and biology) will be combined to study whether and how SOF regulates Hd2, and dissects the functions site of SOF in flowering pathway. We believe this study will largely improve our understanding for the rice flowering regulation network, and provide novel target for rice molecular breeding.