叶片作为水稻光合作用的主要场所，其形态改良是水稻株型育种的重要目标之一。叶片适度卷曲有利于提高光合效率和产量。目前虽已在水稻中克隆获得多个卷叶基因，但局限于单个基因的功能研究，有待于克隆更多卷叶调控基因，构建更加完善的卷叶分子调控网络。另外，已克隆的多数卷叶基因突变后伴随一些不利产量性状，因此没能在育种中得以有效利用。本项目选取了一份水稻半显性内卷叶突变体url1，其株型直立且穗型和育性等产量指标未受影响。目前图位克隆获得了候选基因URL1，该基因编码一转录因子，在突变体中表达量升高。通过在突变体中减量表达和野生型中超表达URL1，验证了URL1调控叶片卷曲的功能。初步筛选到两个URL1的互作蛋白和两个受URL1直接调控的下游基因。将通过遗传、生化及分子生物学的方法研究URL1及其互作蛋白调控叶形的分子机制，构建和完善叶形调控网络，评价URL1基因及其突变体材料在水稻高产育种中的应用价值。

Leaf is the major organ for photosynthesis in rice plant. The improvement of leaf morphology is one of the main targets of rice breeding for ideal plant architecture. Moderate leaf rolling is beneficial for the improvement of photosynthesis rate and grain yield. Although many genes controlling leaf rolling have been cloned in rice, the molecular mechanism underlying leaf rolling is still limited to individual genes and fragmented. More regulatory genes are needed to be cloned to construct detailed and refined molecular regulation network of leaf rolling. Furthermore，most of the cloned genes controlling leaf rolling have not been effectively used in rice breeding, due to some undesired effects on yield parameters. In this project, the semi-dominant mutant upward rolled leaves (url1) was selected from a collection of rice mutants with variant leaf morphologies. The url1 mutant exhibits erect and rolled leaves without side effects on panicle morphology, fertility and grain yield. We cloned the responsible gene URL1 using a map-based cloning approach which encodes a transcription factor. The expression level of URL1 was significantly increased in the url1 mutant. The URL1 gene was confirmed to control rice leaf rolling via downregulation of URL1 expression in the url1 mutant and overexpression in the wild type. We have identified two downstream genes directly regulated by URL1 and two proteins interacting with URL1. We will use genetic, biochemical and molecular technology to reveal the molecular mechanism of URL1 and its interacting proteins in controlling leaf rolling. We will also evaluate the application potential of the URL1 gene and the url1 mutant in the rice high-yield breeding.