Phytophthora sojae effector Avh331 suppresses the plant defence response by disturbing the MAPK signalling pathway

Oomycete plant pathogens translocate hundreds of RXLR effector proteins into host cells to establish an infection; however, the mechanism by which the effector manipulates host defence and promotes pathogenicity remains largely unknown. Here, we generated two independent transgenic Arabidopsis lines of Avh331, an RXLR effector of Phytophthora sojae, and showed that Avh331 suppresses the Arabidopsis mitogen-activated protein kinase (MAPK)-based plant defence activated by the Phytophthora elicitor to promote colonisation of the Phytophthora pathogen. Furthermore, Avh331 suppressed transcriptional activation of resistance marker genes downstream of the MAPK signalling pathway. Similar to the phenotype in Arabidopsis, Avh331 suppressed the MAPK signalling pathway to inhibit the basal defence induced by Phytophthora elicitor INF1 or tobacco MAPK proteins in Nicotiana benthamiana. Taken together, these results indicate that the RXLR effector Avh331 promoted the colonisation of plant pathogens by manipulating the MAPK signalling pathway in plant cells.

► We elucidate the virulence function of one RxLR effector from Phytophthora sojae.
► Avh331 significantly suppressed plant immunity to enhance Phytophthora virulence.
► Avh331 suppress MAP Kinase signalling passway both in Arabidopsis and Nicotiana.