水稻是世界上最主要的粮食作物。作为水稻根系主要组成部分的冠根对其生长发育、产量以及不良环境胁迫的响应等方面都起着十分重要的作用。植物中蛋白质的降解系统广泛地参与植物信号转导、光形态建成、器官发育和非生物胁迫响应等调控途径。植物中RING-finger家族的E3连接酶数量庞大且功能复杂，而水稻中的RING-finger类E3连接酶大多数功能还不是十分得清楚。本课题的主要研究目的是从细胞学、分子生物学、生物化学和遗传学角度解析RING-finger类E3泛素连接酶OsPIS1及其底物在水稻冠根发育中的生物学功能，期望从蛋白质水平揭示水稻冠根发育的调控机制，进一步为水稻根器官发育提供理论基础，为改善水稻根系的形态构型、发育状态，从而增加水稻对逆境胁迫的抗性，氮、磷等营养的高效利用和提高水稻产量提供理论依据和基因资源。

Rice is one of the most important staple food crops in the world. Crown roots are the major components of the rice fibrous root system and play vital roles for rice growth， grain harvest yield, and abiotic stresses response. Protein degradation system is involved broadly in plant signal transduction, photomorphogenesis, organ development, and abiotic stress response pathways. RING (REALLY INTERESTING NEW GENE)-type E3 ligase is a protein family with diverse functions. The function of most of the rice homologues is not well known. The major goal of the present proposal is to characterize the function of rice RING-finger E3 ligase OsPIS1 and its substrate in regulating rice crown root development by using cell biology, molecular biology, biochemistry, and genetics approaches, and to further uncover the molecular mechanism of crown root development at the protein degradation level. The present proposal aims to decipher rice root development mechanism and to provide a theoretical basis for the genetic improvement of root morphological configuration to enhance rice resistance to advert stimuli to improve efficiency of utilization of nutrients such as nitrogen and potassium, and to increase grain yield.