ClSWEET11基因介导西瓜细菌性果斑病感病的分子机制

The plant-pathogenic bacterium Acidovorax citrulli causes bacterial fruit blotch (BFB) of cucurbits, an important seed-borne disease and result in large economic losses in watermelon production worldwide. The pathogen has been listed in the quarantine pests of China. Whereas, strategies for managing BFB are limited and there are no reliable sources of BFB resistance. Despite the economic importance of BFB, very little is known about basic aspects of the biology of A. citrulli and the molecular basis of BFB pathogenesis. We deployed genome-wide gene expression profiling in watermelon using the type III secretion system mutant of A.citrulli coupled with isolation of transposon mutants from A.citrulli. We identified the sugar transporter gene ClSWEET11 as a virulent effector target of A.citrulli. We hypothesized that virulent effectors of A.citrulli could induce the expression of ClSWEET11 gene during infection to provide nutrients for its own growth. We aimed to determine that ClSWEET11 is a major S gene for BFB by using CRISPR genome editing technique. The expected results will highlight a new strategy to improve watermelon BFB resistance through genomic editing of effector-binding element in ClSWEET11 gene promoter. Such characterizations would also likely lead to new watermelon germplasm resources for improved control of BFB. Meanwhile, our work will not only provide useful guidance for crop breeding and agriculture but also expand the understanding of the molecular mechanism of Plant-Pathogen interaction.

西瓜噬酸菌(Acidovorax citrulli)引起的细菌性果斑病(bacterial fruit blotch, BFB)是严重影响全球西瓜产业的种传毁灭性病害。现有栽培品种西瓜都对BFB表现为感病，通过常规抗病育种防控病害难以实现，且西瓜BFB的致病机理尚未十分清楚。本项目前期通过比较野生型和Ⅲ型分泌系统缺失的A.citrulli菌侵染西瓜幼苗的基因表达谱，获得效应蛋白特异诱导调控的感病基因ClSWEET11。计划通过筛选A.citrulli菌突变体库，得到ClSWEET11对应的候选效应蛋白；进而利用基因编辑技术验证ClSWEET11基因及其启动子区效应蛋白特异结合位点的生物学功能，解析BFB特异效应蛋白调控ClSWEET11表达的分子机理；最终明确BFB致病机理，设计并创制出西瓜抗BFB的新型种质，具有较大创新意义与潜在应用价值，也将丰富植物-病原菌互作的分子机制理论。

西瓜细菌性果斑病 (BFB) 近年来在全球普遍发生，已成为严重影响西瓜产业的种传毁灭性病害。揭示西瓜BFB抗病机制并创建抗BFB种质资源具有重要的理论和现实意义。本项目获得了A. citrulli效应蛋白缺失突变体及其侵染条件下效应蛋白特异诱导的西瓜基因表达谱，进一步筛选A. citrulli菌突变体库，获得致病性相关的候选效应蛋白以及受其诱导表达的候选感病基因ClSWEET11和ClMMP；利用基因编辑技术验证了ClSWEET11和ClMMP基因的抗病生物学功能，解析了ClMMP调控BFB感病的机理，设计并创制出了西瓜抗BFB的种质资源。在国际期刊Plant Cell Reports上发表SCI研究论文1篇，培养研究生1人。