果胶降解影响果实品质。其降解产物寡聚半乳糖醛酸（OGs）作为信号物质通过与受体细胞壁相关激酶（WAKs）结合，影响植物的发育及胁迫反应，但在果实中，OGs/WAK作用机制及信号传递却少有研究。前期我们发现，OGs通过ACS2磷酸化诱导番茄果实乙烯生成，促进果实成熟，但OGs是如何通过WAK及下游组分调控ACS的磷酸化分子机制有待深入研究。本项目以番茄ACS2磷酸化调控为研究点，首先获得WAK过表达及WAK缺失果实，验证WAK在OGs诱导的乙烯生成、ACS2磷酸化及果实成熟中作用；再以WAK蛋白激酶域为诱饵，酵母双杂交技术筛选与WAK互作的PP2C蛋白；最后，结合体内CO-IP、BiCF互作、体外磷酸化分析，揭示出OGs/WAK信号传递中WAK/PP2C/MAPK/ACS之间蛋白互作对乙烯生成调控的分子机制。本项目对于完善细胞壁降解产物在果实成熟衰老中分子作用机制具有重要意义。

Pectin degradation affect fruit texture and quality, and its degraded products oligogalacturonic acids (OGs) act as a signal to interact with its receptor wall associated kinases (WAKs), activating many plant development and immune responses. However, few works were carried out on the function of OGs/WAK pathway and its signal transduction in fruits. Our previous study found OGs promoted tomato fruit ripening through the regulation of expression of aminocyclopropane-1-carboxylic acid synthase2 (ACS2) at the transcriptional and post-translational levels. To further investigate the effect of WAK on the OGs-induced ethylene production and signal transduction, OGs treated WAK overexpressed or knocked out fruits were sampled to measure ethylene production, phosphorylated LeACS2 expression level and the activities of protein kinase and phosphatase. WAK conserved kinase domain was used to screen type 2C protein phosphatases (PP2C) by Yeast Two-Hybrid Analysis, then BiFC assay was used to test their interaction in vivo. To establish the interaction network of components regulating the phosphorylated LeACS2 in OGs/ WAK pathway, in vitro phosphorylation and dephosphorylation assay were carried out with different combination of recombinant purified WAK, PP2C, MAPK and ACS2 proteins. The project will be helpful for enriching our understanding on the function of cell wall pectin degradation products on the regulation of ethylene production and tomato fruits ripening.