Two cerato-platanin proteins FocCP1 interact with MaPR1 and contribute to virulence of Fusarium oxysporum f. sp. cubense to banana

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) causes destructive wilt disease to banana cultivation. However, knowledge of mechanisms in virulence regulation of Foc TR4 is still inadequate. In our previous work, two hypothetical FocCP1 proteins that belong to the cerato-platanin (CP) family were identified in the secretome of Foc TR4. In the present study, knock-out mutants of two FocCP1 were constructed and functions of two proteins were investigated. The results showed that the two FocCP1 play important roles in regulation of full virulence but are not required for vegetative growth or conidiation of the pathogen; besides, there is a functional redundancy between the two FocCP1. Moreover, we found that FocCP1 proteins interact with MaPR1 proteins through yeast two-hybrid and BiFC test. Our results suggest that FocCP1 proteins are important for the virulence of Foc TR4 and might inhibit the antifungal activity of MaPR1 by directly interacting with them.

尖孢镰刀菌古巴专化型热带4号小种（Foc TR4）可对香蕉种植造成毁灭性的枯萎病危害。然而，当前学界对Foc TR4致病调控机制的认知仍存在不足。在前期研究中，我们从Foc TR4的分泌组（secretome）中鉴定出两个隶属于凝脂素（cerato-platanin, CP）家族的假定FocCP1蛋白。本研究构建了两个FocCP1基因的敲除突变体，并对这两种蛋白的功能进行了系统探究。结果显示，这两个FocCP1蛋白在调控病原菌完全致病力方面发挥关键作用，但并非病原菌营养生长与产孢过程所必需；除此以外，二者之间存在功能冗余现象。此外，我们通过酵母双杂交（yeast two-hybrid）与双分子荧光互补（BiFC）实验证实，FocCP1蛋白可与MaPR1蛋白发生相互作用。本研究结果表明，FocCP1蛋白对Foc TR4的致病力具有重要意义，且可能通过直接结合MaPR1蛋白抑制其抗真菌活性。