水稻OsLG1基因调控穗型的分子机理

Panicle architecture is a key agronomical factor determining grain yield and thus has been a major target of rice domestication and improvement. Revealing the molecular mechanism of the regulating and domestication of the panicle architecture is one of the key research subjects in the research area of rice genetics and domestication. Funded by NSFC, we have cloned the OsLG1 gene controlling the panicle transition during rice domestication using map-based cloning method. The regulatory region mutations residing in about 11 kb upstream of the OsLG1 gene, result in a compact panicle architecture in cultivars during rice domestication. In this project, we will further identify the role of a long non-coding RNA lying in the 11 kb upstream region, and reveal the molecular mechanism of regulating OsLG1 gene. Meanwhile, we will identify the target gene regulated by OsLG1 and new genes controlling panicle architecture using forward genetic and reverse genetic methods. We will further reveal the molecular genetics mechanism of the OsLG1 gene regulating rice panicle architecture. The results will provide molecular evidence for understanding molecular mechanism of domestication and regulating of rice panicle architecture, and provide theory for improving rice panicle architecture using molecular breeding method.

穗型是影响水稻产量的重要农艺性状，也是水稻驯化和遗传改良的重要目标。解析穗型调控与进化的分子机理是水稻遗传与进化研究领域重要课题之一。在国家自然科学基金的资助下，我们克隆了控制野生稻散穗的OsLG1基因，发现在水稻驯化过程中，选择该基因上游11 kb附近的顺式调控元件变异导致栽培稻穗型变紧。本项目拟在此基础上，鉴定功能性变异区域内的一个长链非编码RNA对OsLG1基因的调控作用；同时，采用正向与反向遗传学的方法，分离、鉴定OsLG1基因调控的靶基因及控制穗型的新基因，进一步解析OsLG1基因调控水稻穗型的分子机理。研究结果不仅为解析水稻穗型调控和进化的分子机理这一重要科学问题提供证据，同时还为穗型的分子改良提供重要参考。

水稻穗型是株型的重要构成因子，不仅是遗传改良的目标性状，也是早期驯化的重要目标性状。由野生到散穗变为栽培稻的紧穗是水稻驯化的关键步骤之一。我们前期研究发现水稻OsLG1基因控制野生稻散穗形态，在水稻驯化过程中，选择该基因上游顺式调控变异导致栽培稻的紧穗表型。本项目在此基础上，从珍汕97B与Amol3杂交的分离群体里面获得一个散穗突变体ZF16，遗传分析表明突变体ZF16散穗形态由一对显性基因控制，通过基因定位和遗传转化实验鉴定了LG1基因上游一个48bp缺失变异导致OsLG1基因表达水平升高，引起穗型变散，生物信息学分析结果表明该缺失变异可能是生长素结合位点，该研究结果揭示了水稻穗型调控的分子机制; 同时，利用反向遗传实验分离了一个LG1基因的抑制基因，并发现其与OsLG1存在遗传与分子互作关系，研究结果为水稻穗型发育的分子遗传机理提供了新的知识。