Abstract：
Plants have developed intricate immune mechanisms to impede Phytophthora colonization. In response, Phytophthora secretes RxLR effector proteins that disrupt plant defense and promote infection. The specific molecular interactions through which Phytophthora RxLR effectors undermine plant immunity, however, remain inadequately defined. In this study, we delineate the role of the nuclear-localized RxLR effector PcAvh87, which is pivotal for the full virulence of Phytophthora cinnamomi. Gene expression analysis indicates that PcAvh87 expression is significantly upregulated during the initial infection stages, interacting with the immune responses triggered by the elicitin protein INF1 and pro-apoptotic protein BAX. Utilizing PEG/CaCl2-mediated protoplast transformation and CRISPR/Cas9-mediated gene editing, we generated PcAvh87 knockout mutants, which demonstrated compromised hyphal growth, sporangium development, and zoospore release, along with a marked reduction in pathogenicity. This underscores PcAvh87\'s crucial role as a virulence determinant. Notably, PcAvh87, conserved across the Phytophthora genus, was found to modulate the activity of plant immune protein 113, thereby attenuating plant immune responses. This implies that the PcAvh87-mediated regulatory mechanism could be a common strategy in Phytophthora species to manipulate plant immunity. Our findings highlight the multifaceted roles of PcAvh87 in promoting P. cinnamomi infection, including its involvement in sporangia production, mycelial growth, and the targeting of plant immune proteins to enhance pathogen virulence.
摘要：
植物已经开发出复杂的免疫机制来阻止疫霉定殖。作为回应,疫霉分泌破坏植物防御并促进感染的RxLR效应蛋白。疫霉RxLR效应子破坏植物免疫的特定分子相互作用，然而,仍然没有充分定义。在这项研究中,我们描述了核定位的RxLR效应子PcAvh87的作用，这对于肉桂疫霉的全毒力至关重要。基因表达分析表明，PcAvh87表达在初始感染阶段显著上调，与诱导蛋白INF1和促凋亡蛋白BAX触发的免疫反应相互作用。利用PEG/CaCl2介导的原生质体转化和CRISPR/Cas9介导的基因编辑，我们产生了PcAvh87基因敲除突变体,表现出菌丝生长受损，孢子囊发育,和游动孢子释放，伴随着致病性的显著降低。这强调了PcAvh87作为毒力决定因素的关键作用。值得注意的是,PcAvh87，在疫霉属中保守，被发现可以调节植物免疫蛋白113的活性，从而减弱植物的免疫反应。这意味着PcAvh87介导的调节机制可能是疫霉物种操纵植物免疫的常见策略。我们的发现强调了PcAvh87在促进肉桂感染中的多方面作用，包括参与孢子囊生产，菌丝体生长，和靶向植物免疫蛋白以增强病原体毒力。
