水稻颖花开放是由分布于子房基部的一对浆片吸水膨胀启动的，浆片膨胀撑开内稃和外稃，同时花丝伸长花药外露开裂散粉最终完成授粉。通过对水稻颖花开放前后浆片的组织形态，细胞结构及水势调节相关物质的变化等方面的研究使人们对开颖过程中浆片细胞的生理生化过程及行为模式有了初步的认识，但浆片膨胀介导的水稻开颖的分子机制的研究却依然匮乏，主要原因之一是缺乏合适的闭颖突变体。目前已报道的的闭颖突变体均有比较严重的花器官发育缺陷，难以适合后期水稻开颖的分子机制研究的开展。本项目前期鉴定的闭颖突变体hrt2浆片发育正常，能结实并获得子代，该突变基因编码一个高温响应的转录因子，能在小穗及浆片中特异性高表达。本项目将以OsHRT2为切入点，深入研究水稻开颖的信号通路及其调控机制。为解决水稻杂交制种中花时不遇及防范转基因水稻基因漂流等重要农业生产问题提供理论基础和基因资源。

Rice floret opening is initiated by the swelling of a pair of lodicules which lying at the base of ovary. Swelled lodicules lever away the lemma and palea, at the same time, the filaments quickly elongate which allows anthers to emerge for pollination. Previous studies focused on the histomorphology and physiology changes of lodicule cells during anthesis. However, the molecular mechanism of rice anthesis remains obscure, as lacking of proper genetic materials. Most of the cleistogamous mutants have been identified are lodiculeless and unsuitable for further genetic study. Here, we identified a novel cleistogamous mutant hrt2 in rice. hrt2 mutant has normal lodicules and other floret organs and has no problem to propagate. Our preliminary data showed that OsHRT2 highly expressed in panicles, especially in lodicules. The expression level of OsHRT2 can be induced by high temperature and exogenous MeJA. In this study, we are going to characterize the biological function of OsHRT2 in rice anthesis with genetics, biochemistry and molecular biological approaches. We hope our work will lead new insights into the molecular mechanisms of floret opening in rice and help breeders resolve the problems in agricultural production, such as asynchronous floret opening in hybrid breeding and gene flow in transgenic rice growth.