Ⅲ型效应子GALA对青枯菌在两种寄主植物上致病性的影响

Involvement of GALA effectors in Ralstonia solanacearum disease development towards two host plants

摘要:

[目的]研究Ⅲ型效应子GALAs对青枯菌OE1-1在不同寄主植物致病性上的影响。[方法]构建青枯菌OE1-1的多种GALA缺失突变体，通过根切和叶片注射等方法研究GALAs对青枯菌OE1-1致病力和细胞内增殖能力的影响。[结果]GALA多基因缺失突变体对寄主烟草的致病力减弱，在烟草体内细菌繁殖能力较野生型明显降低，但在寄主番茄上不影响其致病性。[结论]GALA效应子对青枯菌OE1-1在烟草植株致病性上展现协同作用。

Abstract:

[Objective] By testing the virulence of single and multiple GALA mutants generated in Ralstonia solanacearum strain OE1-1, we evaluated the pathogenicity of these effectors in different host plants.[Methods] The deletion mutant of R. solanacearum OE1-1 was constructed through double crossover. Deletion of the target gene was confirmed by colony PCR. Virulence assay and bacterial multiplication were measured by root-cutting and leaf infiltration respectively. Tobacco (Nicotiana tabacum cv. Bright Yellow) and tomato (Lycopersicon esculentum cv. Moneymaker) were adopted as host plants to inoculate.[Results] Deletion mutants of each effector gene barely affected the bacterial virulence in tobacco. A mutant RK7022 with the deletion of all seven gala genes showed 2-days delayed virulence on tobacco compared with the wild type. The bacterial multiplication capacity of deletion mutants correlated with the phenotypes on host plants. Pathogenicity test on tomato among GALA mutants and wild type OE1-1 showed no difference.[Conclusion] GALA effectors contributed collectively to pathogenicity of OE1-1 on tobacco but not on tomato. Some effectors might play more important roles in R. solanacearum pathogenicity.