Oleanolic Acid Induces the Type III Secretion System of Ralstonia solanacearum.
Oleanolic Acid Induces the Type III Secretion System of Ralstonia solanacearum.
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DOI：
10.3389/fmicb.2015.01466
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发表时间：
2015
影响因子：
5.2
通讯作者：
Yang L
中科院分区：
文献类型：
--
作者：
Wu D;Ding W;Zhang Y;Liu X;Yang L
青枯雷尔氏菌（Ralstonia solanacearum）是引起青枯病的病原菌，能在自然界中侵染多种寄主植物。III型分泌系统（T3 SS）是该细菌的主要毒力决定因子。研究表明，植物源化合物能抑制或诱导某些植物病原细菌的T3 SS，但目前还没有在R.青枯菌属在这项研究中，总共筛选了50种不同的化合物，其中几乎一半（50种中的22种）显著抑制或诱导R.青枯菌属基于对T3 SS的强烈诱导活性，选择T3 SS诱导剂油酸（OA）进行进一步研究。我们发现OA通过HrpG-HrpB途径诱导T3 SS的表达。一些III型效应基因在添加OA的T3 SS诱导培养基中被诱导。此外，OA仅靶向T3 SS，不影响其他毒力决定因子。最后，我们观察到OA对T3 SS的诱导加速了烟草上的病害进展。总的来说，我们的研究结果表明，植物源化合物是一个丰富的来源R。青枯菌T3 SS调节剂，这可能被证明是有用的工具，询问这一关键的毒力途径的调节。
Ralstonia solanacearum, the causal agent of bacterial wilt, can naturally infect a wide range of host plants. The type III secretion system (T3SS) is a major virulence determinant in this bacterium. Studies have shown that plant-derived compounds are able to inhibit or induce the T3SS in some plant pathogenic bacteria, though no specific T3SS inhibitor or inducer has yet been identified in R. solanacearum. In this study, a total of 50 different compounds were screened and almost half of them (22 of 50) significantly inhibited or induced the T3SS expression of R. solanacearum. Based on the strong induction activity on T3SS, the T3SS inducer oleanolic acid (OA) was chosen for further study. We found that OA induced the expression of T3SS through the HrpG-HrpB pathway. Some type III effector genes were induced in T3SS inducing medium supplemented with OA. In addition, OA targeted only the T3SS and did not affect other virulence determinants. Finally, we observed that induction of T3SS by OA accelerated disease progress on tobacco. Overall our results suggest that plant-derived compounds are an abundant source of R. solanacearum T3SS regulators, which could prove useful as tools to interrogate the regulation of this key virulence pathway.