Apoplastic ascorbate oxidases (AOs) play a critical role in reactive oxygen species (ROS)-mediated innate host immunity by regulating the apoplast redox state. To date, little is known about how apoplastic effectors of the rice blast fungus Magnaporthe oryzae modulate the apoplast redox state of rice to subvert plant immunity. In this study, we demonstrated that M. oryzae MoAo1 is an AO that plays a role in virulence by modulating the apoplast redox status of rice cells. We showed that MoAo1 inhibits the activity of rice OsAO3 and OsAO4, which also regulate the apoplast redox status and plant immunity. In addition, we found that MoAo1, OsAO3, and OsAO4 all exhibit polymorphic variations whose varied interactions orchestrate pathogen virulence and rice immunity. Taken together, our results reveal a critical role for extracellular redox enzymes during rice blast infection and shed light on the importance of the apoplast redox state and its regulation in plant-pathogen interactions.

质外体抗坏血酸氧化酶 (AOs) 通过调节质外体氧化还原状态在活性氧 (ROS) 介导的先天宿主免疫中发挥关键作用。迄今为止，人们对稻瘟病真菌稻瘟病菌的质外体效应子如何调节水稻的质外体氧化还原状态以破坏植物免疫知之甚少。在这项研究中，我们证明了M. oryzaeMoAo1 是一种 AO，通过调节水稻细胞的质外体氧化还原状态在毒力中发挥作用。我们发现 MoAo1 抑制水稻 OsAO3 和 OsAO4 的活性，这也调节了质外体氧化还原状态和植物免疫。此外，我们发现 MoAo1、OsAO3 和 OsAO4 都表现出多态性变异，其不同的相互作用协调病原体毒力和水稻免疫。总之，我们的研究结果揭示了细胞外氧化还原酶在稻瘟病感染过程中的关键作用，并阐明了质外体氧化还原状态的重要性及其在植物-病原体相互作用中的调节。