乙烯是一种重要的植物激素。EIN2是乙烯信号通路中的核心正调组分，申请人近年来的研究揭示了其在细胞质中激活乙烯反应的“翻译抑制”机制。但该过程的生化机理仍有待深入研究。最近，申请人通过IP-MS实验发现P-body组分、mRNA翻译起始因子eIF4E/4G/4A、RNA结合蛋白PUBP1等在植物体内与EIN2发生相互作用。遗传分析表明eIF4G和PUBP1对植物响应乙烯具有重要的作用。初步的生化分析表明eIF4G可能是翻译机器中EIN2的靶蛋白；PUBP1则通过直接与mRNA结合进而介导EIN2与mRNA之间的互作。下一步，本申请拟运用遗传学、分子生物学、生物化学、细胞生物学、生物信息学等方法，深入研究PUBP1-EIN2-eIF4G所调控的翻译过程。以上研究有望解析EIN2调控mRNA翻译过程的详细生化机理，阐明乙烯作用的新机制，并对农业生产和生物技术育种提供重要的理论支持。

The gaseous phytohormone ethylene is essential for plant growth and development as well as responses to abiotic and biotic stresses. EIN2 is an essential positive regulator in ethylene signal transduction pathway. Previous work by the applicant found a new branch of ethylene signaling pathway in cytoplasm, where EIN2 activates ethylene response through translational repression mode. However, the biochemical mechanism of this process remains unclear. Recently, we isolated several EIN2-associating proteins using IP-MS assay. These proteins include some components of P-body, translation machinery proteins eIF4e/4G/4A, and a family of RNA binding proteins named PUBP1. Our genetic analysis displayed that eIF4G and PUBP1 play important roles in ethylene signaling cascade. Biochemical studies revealed that EIN2 might directly interact with eIF4G to target to translation machinery. Further investigation found that PUBP1 mediates the association between EIN2 and mRNA through directly binding to mRNA. In this proposal, we aim to uncover the detailed mechanisms underlying PUBP1-EIN2-eIF4G complex-directed translational inhibition using combined technologies including genetics, molecular biology, biochemistry, cell biology, and bioinformatics. This study will improve our understanding of actions of ethylene in plants, shed new lights on studies in plant signal transduction, and greatly support agricultural practice.