水稻组蛋白H2B泛素化修饰调控雄配子体发育的分子机制

The development of male gametophyte is pivotal for fertilization and seed setting of crops. Some key genes are regulated temporally and spatially during male gametophyte development. Histone H2B monoubiquitination (H2Bub1) is of importance for chromatin remodeling and transcriptional regulation. H2Bub1 plays several roles in plants, but its function in male gametophyte development is unclear. The physiological function and molecular mechanism of H2Bub1 in rice is poorly understood. Here, loss of function mutants are used to studied the regulary mechanism of H2Bub1 on rice male gametophyte development. OsHUB1 and OsHUB2 (HISTONE UBIQUITINATION 1 and 2 in Oryza sativa) are putative E3 ligase of histone H2B ubiqutination of rice. Preliminary results indicated the two proteins of rice are related to male gametophyte development, as the rice hub1 and hub2 mutants displayed low seed setting rate, poor pollen activity, decreased number of pollen grains, and abnormal-shaped tricelcular stage microspores. In this study, mutants, overexpressed and RNAi transgenic rice of OsHUB1 and OsHUB2 are used as plant materials. The character of subcellular localization, protein interaction, expression pattern, biochemical properties of the two proteins are to be analyzed through cell biology, biochemistry, genetics and transcriptome analysis. Furthermore, the expression and regulation of key genes by OsHUB1 and OsHUB2 during anther or gametophyte development are to be indentified and verified. This project is aimed to reveal the underlying regulary mechanism of histone H2B monoubiquitination on rice male gametophyte development. This project will provide theoretical basis for crop improvement of yied traits.

在雄配子体发育过程中，基因的时空表达受严格的调控。组蛋白H2B单泛素化修饰的重要作用之一是基因转录调控，介导植物多个生物学过程，但在雄配子体发育中的功能尚不清楚。本项目主要用水稻缺失突变体来分析其修饰对水稻雄配子发育的调控机制。前期结果表明其修饰的关键成员OsHUB1和OsHUB2可能与雄配子体发育有关。其突变体hub1和hub2表现出结实率降低，花粉粒活力降低，部分三核期花粉粒的形态异常。本研究基于本课题组前期研究结果，拟利用遗传突变体、超表达和RNAi转基因水稻为材料，结合分子遗传学、细胞生物学、生物化学和转录组学等技术，探索水稻雄配子体发育过程中组蛋白泛素化修饰的调控机理。主要内容包括突变体和转基因材料的遗传与雄配子体细胞学分析、蛋白互作及其生化特征鉴定、E3连接酶作用模式与基因表达调控。本项目不仅对水稻雄配子体发育调控机制具有重要意义，而且将为水稻育种提供可能的理论基础。

组蛋白H2B单泛素化修饰的重要作用之一是基因转录调控，介导植物多个生物学过程，但在花药发育中的功能尚不清楚。本项目主要以水稻功能缺失突变体为材料，.结合细胞生物学、生物化学、转录组学等技术，分析组蛋白H2B泛素化修饰在水稻花药发育中的调控机制。主要研究内容包括突变体花药发育的细胞学观察、蛋白质互作及其生化性质分析与基因表达调控。主要结果是，水稻OsHUB1和OsHUB2形成四聚体发挥E3连接酶的功能，介导组蛋白H2B的单泛素化修饰。在花药发育的后期，H2B泛素化修饰调控绒毡层降解关键基因UDT1和OsCP1的表达，二者的表达对于花药发育后期绒毡层降解和花粉粒的形成至关重要。本项目不仅对水稻雄性生殖发育调控机制具有重要意义，而且将为水稻育种提供可能的理论基础。...........................................................................