野油菜黄单胞菌效应蛋白AvrXccC抑制鞭毛蛋白诱导的植物免疫反应

Xanthomonas campestris pv.campestris effector protein AvrXccC suppresses flagellin-induced innate immunity

野油菜黄单胞菌III型分泌效应蛋白AvrXccC在拟南芥rar1突变体上发挥毒性功能,然而,AvrXccC是如何发挥毒性功能的,目前还不清楚。本研究构建了A6vrXccC在rar1突变体上的转基因植株,通过接种DC3000 hrcC突变体,发现AvrXccC/rar1转基因植株可以促进hrcC的毒性功能。进一步研究发现,AvrXccC/rar1转基因植株抑制细菌鞭毛蛋白激发的活性氧爆发、胼胝体沉积及下游NHO1和FRK1基因的表达;但AvrXccC不抑制鞭毛蛋白诱导的MAPK激酶活性。研究表明,AvrXccC抑制植物先天免疫反应可能独立于MAPK信号通路之外,为将来分离AvrXccC在植物体内的毒性靶标奠定了基础。

AvrXccC, a type III effector protein of Xanthomonas campestris pv. campestris （Xcc）, acts as a virulence factor in rarl mutant. However, little is known about the virulence mechanisms of AvrXccC. In this study, we demonstrated xhsX AvrXc-cC/ rarl transgenic plants enhance the DC3000 hrcC virulence and suppress flg22-induced oxidative burst and callose deposition, as well as FRK1 and NHOl gene expression. Interestingly, AvrXccC/rarl transgenic plants cannot inhibit flg22-induced MAPKs activity, suggesting that AvrXccC is capable of inhibiting signaling of plant immunity in a MAPK independent manner. Overall, this study provides a basis for future research aimed at isolating virulence targets of AvrXccC in plants.