Verticillium dahliae is a kind of pathogenic fungus that brings about wilt disease and great losses in cotton. The molecular mechanism of the effectors in V. dahliae regulating cotton immunity remains largely unknown. Here we identified an effector of V. dahliae, VdPHB1, whose gene expression is highly induced by infection. VdPHB1 protein is localized in the intercellular space of cotton plants. Knockout VdPHB1 gene in V. dahliae had no effect on pathogen growth, but decreased the virulence in cotton. VdPHB1 ectopically expressed Arabidopsis plants were growth-inhibited and significantly susceptible to V. dahliae. Further, VdPHB1 interacted with the type II metacaspase GhMC4. GhMC4 gene silenced cotton plants were more sensitive to V. dahliae with reduced expressions of pathogen defense-related and programmed cell death genes. The accumulation of GhMC4 protein were concurrently repressed when VdPHB1 protein expressed during infection. In summary, these results revealed a novel molecular mechanism of virulence regulation that the secreted effector VdPHB1 represses the activity of cysteine protease for helping V. dahliae infection in cotton.

中文翻译：

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大丽黄萎病效应子 VdPHB1 促进棉花致病性并与免疫蛋白 GhMC4 相互作用

大丽黄萎病是一种引起棉花枯萎病、造成重大损失的病原真菌。大丽葡萄球菌调节棉花免疫的效应子的分子机制仍然很大程度上未知。在这里，我们鉴定了大丽弧菌的效应子 VdPHB1，其基因表达受到感染的高度诱导。 VdPHB1 蛋白定位于棉花植物的细胞间隙中。敲除大丽葡萄球菌中的VdPHB1基因对病原菌生长没有影响，但降低了棉花中的毒力。 VdPHB1 异位表达的拟南芥植物生长受到抑制，并且对大丽葡萄球菌显着敏感。此外，VdPHB1 与 II 型元半胱天冬酶 GhMC4 相互作用。 GhMC4 基因沉默的棉花植株对大丽葡萄球菌更加敏感，病原体防御相关基因和程序性细胞死亡基因的表达减少。当VdPHB1蛋白在感染过程中表达时，GhMC4蛋白的积累同时受到抑制。总之，这些结果揭示了一种新的毒力调节分子机制，即分泌效应子VdPHB1抑制半胱氨酸蛋白酶的活性，从而帮助大丽弧菌感染棉花。