植物种子和器官大小是重要的农艺性状，对其调控机制的研究具有重要的理论意义和应用价值,然而目前对植物种子和器官大小调控的分子机理尚不清楚。我们实验室分离了一系列影响种子和器官大小的突变体，其中da2-1表现为种子和器官增大。我们已经克隆了DA2基因，它编码一个未知功能的蛋白（预测与蛋白泛素化过程相关），与我们以前报道的DA1、DAR1和DAR2不具有同源性。前期研究结果表明DA2与DA1在遗传上具有协同效应，且DA2和DA1蛋白可以直接互作。本项目利用遗传学、细胞生物学、分子生物学和生物化学等技术，通过分析DA2与其它已知调控种子和器官大小的基因的遗传关系、分析DA2基因的表达模式和蛋白亚细胞定位、筛选和鉴定DA2的相互作用蛋白及DA2调控的下游基因，初步阐明DA2调控种子和器官大小的分子机制。

The final size of seeds and organs is an important agronomic trait that affects seed yield and biomass。 However, the molecular mechanisms that control seed and organ size are largely unknown. Our group have isolated a series of seed and organ size mutants in Arabidopsis, among which, da2-1 mutant has larger seeds and organs than wild type. We have cloned the DA2 gene, which encodes an unknown protein predicted involved in protein ubiquitination pathway.A genomic copy of DA2 has complemented the seed and organ size phenotype of da2-1.Overexpression of DA2 resulted in small plants.We have shown that DA2 synergistically acts with DA1, and the two proteins binds each other. In this proposal,a combination of genetic, molecular, cytological and biochemical methods will be used to study genetic interactions between DA2 and known genes controlling seed and organ size, expression patterns and subcellular localization of DA2, DA2-interacting proteins, and DA2-regulated genes. These studies will reveal the molecular mechanisms that DA2 controls seed and organ size.