水稻雌蕊发育新调控基因ST1的分子机制研究

Normal development of pistil is critical for reproduction in plants and plays a key role in derterming yield and quality in crops. Therefore, studying pistil development has great significance to improve the yield and quality of crops. XHS family, highly expressed in pistil, is a novel plant-specific family, while the function and molecular mechanism of XHS genes remains poorly understood. In the previous research of rice XHS family, we found that one gene, named as ST1, may be a key regulator of controlling pistil development. The st1 mutant plant showed loss of stigma and style, which failed to pollinate and reproduce.ST1 is a typical XHS protein and was identified as a nuclear protein,which could regulate the expression of C class gene DL and OsMADS3 controlling pistil development.In this project, we plan to research the function and regulation pattern of ST1, investigate the association with hormones and epigeneticis and illustrate the molecular mechanism of regulating pistil development by means of genetic complementation, electron microscope scanning, microarray and yeast two-hybrid etc. Predicted results of this project will provide important clues not onlt to the functions of ST1 and other XHS genes, but also to illustrate the molecular mechanism of pistil development and enrich ABCE model in rice.

雌蕊发育是否正常直接关系到植株能否正常开花结实，因此，研究雌蕊发育对于植物繁衍后代，提高作物产量，改良作物品质有着重要的意义。在雌蕊中高度表达的XHS family 是植物特有的新基因家族，目前有功能报道的XHS基因还非常少，并且缺乏深入的分子机制研究。通过对水稻中的XHS 基因研究，我们发现其中的一个成员ST1是控制柱头和花柱形成的关键基因，突变体st1表现为柱头和花柱缺失，导致无法授粉而不能结实。ST1是一个典型的XHS蛋白，亚细胞定位实验显示是一个核蛋白，能调控C类基因DL和OsMADS3的表达。本项目拟通过遗传互补、电镜扫描、芯片技术和酵母双杂交等方法，研究基因ST1的功能以及调控模式，探讨ST1与激素、表观调控的关系，阐明ST1调控水稻花柱和柱头发育的分子机制。研究结果不仅会为研究其他XHS基因的功能提供了重要的线索，而且对阐释植物雌蕊发育的调控模式具有十分重要的意义。

雌蕊发育对水稻的产量、品质都有决定性的影响，雌蕊发育是否正常直接关系到植株能否正常开花结实，因此，研究雌蕊发育对于植物繁衍后代，提高作物产量，改良作物品质有着重要的意义。前期研究发现基因ST1 是控制柱头和花柱形成的关键基因，突变体st1 表现为柱头和花柱缺失，导致无法授粉而不能结实。 亚细胞定位实验显示ST1是一个核蛋白。启动子分析和原位杂交实验显示ST1在雌蕊中高度表达。超表达ST1基因能够增加粒型大小和植株产量,进一步分析发现ST1基因调控基因的表达介导雌蕊的发育。Southern blot发现ST1介导了CG和CHG两种形式的甲基化调控，进一步分析发现ST1调控了水稻4个甲基化转移酶的表达，暗示ST1通过RdDM途径调控雌蕊发育基因介导柱头的发育。研究结果不仅会为研究其他XHS 基因的功能提供了重要的线索，而且对阐释植物雌蕊发育的调控模式和丰富水稻ABCE 模型具有十分重要的意义。