水稻de novo基因OsJDG1调控籼粳粒型分化的机理研究

亚洲栽培稻籼粳两个亚种最直接外观表现是粒型的分化：籼稻多为长粒型，粳稻多为圆粒型，解析亚种间粒型分化的基因基础具有重要理论和应用价值。起源于非编码区的de novo基因对物种分化具有重要作用，但尚无结合表型对水稻de novo基因群体遗传演化和功能鉴定的报道。申请人发现一个de novo基因OsJDG1主要出现在粳稻中，绝大部分籼稻没有该基因；突变体和群体分析发现该基因缺失导致粒长变长、粒宽降低，表明其参与粒型的调控。本项目拟构建多个粳稻品种OsJDG1基因突变体和过表达材料，并互补至多个籼稻品种，综合应用多种分子生物学方法，解析其调控籼粳粒型分化的分子机制和遗传调控网络，并明确其育种应用价值；进一步结合表型和基因组数据分析，解析OsJDG1基因的群体进化遗传特征，阐明其在水稻驯化和籼粳分化中的作用。结果将对解析水稻亚种分化遗传基础具有重要理论价值，并为亚种间优良基因的利用提供重要信息。

Asian cultivated rice (Oryza sativa) contains two major subspecies, indica and japonica. The most direct phenotypic difference between these two subspecies is the difference in grain shape, and most indica germplasm belong to long grain type, while japonica germplasm are mostly round grain type. It is of great theoretical and practical value to illustrate the gene basis of grain shape difference between subspecies. It was suggested that de novo genes, which originated from previous non-coding region, play critical roles in species differentiation. However, there are neither report of population genetic and evolutionary analyses for rice de novo genes through combination of phenotypic and genomic data, no functional detection of any rice de novo genes. The applicant previously noticed that OsJDG1, a rice de novo gene, was dominantly present in japonica population. However, the vast majority of indica cultivars do not possess this gene. Mutant and population analyses revealed that the loss-of-function mutants of OsJDG1 will result in increased grain length (GL) and decreased grain width (GW), suggesting that the gene OsJDG1 is involved in the regulation of rice grain shape. In this project, some genetic materials will be constructed, including CRISPR/Cas9-induced mutants and over-expression plants of some japonica cultivars, and the complementary plants of some indica cultivars. These genetic materials will be further used to illustrate the molecular mechanism and regulatory network of rice OsJDG1 in regulating the difference of grain shape between indica and japonica, through combination of multiple molecular biological methods. In addition, the roles of OsJDG1 in rice domestication and subspecies divergence will be illustrated through population genetic analyses combined phenotypic and genomic data. The results of this project will have important theoretical value in understanding the genetic basis of rice subspecies differentiation, and provide important information for the exchange and utilization of favorable genes between two subspecies.