组蛋白乙酰化修饰控制水稻粒型和粒重的遗传调控网络研究

Enhanced crop production is necessary in view of the increasing population of our country. Grain shape and weight is an important determinant of crop yield; however, its underlying mechanisms of development and genetics control are largely unknown. We identified, by map-based cloning method, a new grain-shape-and-weight gene OsglHAT1 that encodes a novel histone acetyltransferase. Sequence blast analysis against public databases identified fifty-nine putative OsglHAT1 homologs, including five of them in rice; all of the homologs are found restricted to the plant kingdom. Based on these results, we put research emphases in this project on analyses of biological functions and molecular mechanisms of the five OsglHAT1’s homologs in rice, especially these two exhibiting the highest sequence similarities to OsglHAT1, which are localized on chromosome 2 and 4. Meanwhile, the results of our previously in vitro and in vivo HAT assays and RNA-Seq indicated that OsglHAT1 functions indeed as a histone acetyltransferase, and most likely through the regulation of transcription involving a variety of signaling pathways. We will identify the downstream and upstream genes of the OsglHAT1’s action, and shed light on the molecular bases of grain shape and weight regulation from the aspects of the molecular genetics, physiology and biochemistry, aiming to improve crop production in breeding and to secure food supply in China.

我国人口将继续增长，对粮食的需求持续增加。粒型和粒重是作物产量的构成要素之一；不过，人们对其发育机理和遗传调控网络知之甚少。我们利用图位克隆的手段，分离到一个新的控制水稻粒型和粒重的基因OsglHAT1，编码一个新类型的组蛋白乙酰转移酶。利用现有公共数据库进行的序列分析表明，该基因是植物界所特有的新基因；其在植物界共有59个疑似同源基因，包括水稻中的5个。在此研究基础上，本项目拟重点探讨该基因在水稻中的这5个（特别是定位于水稻2号和4号染色体上的、与OsglHAT1同源性最高的两个）同源基因的生物学功能和分子作用机理。同时，我们前期的组蛋白乙酰转移酶体内、体外实验和RNA-Seq结果表明，OsglHAT1是一个真正的组蛋白乙酰转移酶，很可能通过参与调控基因转录介导了诸多信号途径。本项目还将鉴定与该基因互作的上下游基因，解析其遗传调控网络，为我国作物高产培育提供理论支持，维护国家粮食安全。

水稻OsglHAT1是一个新的组蛋白乙酰化酶，调控谷粒大小；至今我们对其遗传网络不清楚。同时，该基因存在5个疑似的水稻同源基因，功能皆未知。本课题通过以OsglHAT1为诱饵，筛选酵母双杂交cDNA文库寻找其互作因子，结合运用现代组学、分子生物学、生物化学和细胞生物学等方法与技术，对OsglHAT1与其互作因子HIP1的遗传调控网络，以及对OsglHAT1同源基因的生物学功能进行初步探索。首先，利用RNA-Seq技术和转基因水稻材料，我们分析过表达OsglHAT1在幼穗发育时期对基因表达差异的影响。同时，我们通过筛选酵母双杂交cDNA文库，获得一个新的RING-H2类型的谷粒大小控制因子HIP1，并利用酵母双杂交、BiFC和Pull-down等实验证实这一互作。此外，我们利用转基因技术和表型分析发现，水稻中OsglHAT1同源基因也调控谷粒大小。综合上述结果，本研究为深入研究OsglHAT1及其同源基因调控水稻谷粒大小的遗传网络和生物学功能奠定了重要工作基础。项目资助发表学术论文1篇，待发表1篇。培养硕、博士研究生2名，其中1名已经取得硕士学位，1名博士在读。项目投入经费100万元，支出79.90073万元。剩余经费20.09917万元，计划用于本项目研究后续支出。