The spindle assembly checkpoint (SAC) proteins are conserved among eukaryotes safeguarding chromosome segregation fidelity during mitosis. However, their biological functions in plant‐pathogenic fungi remain largely unknown. In this study, we found that the SAC protein MoMad1 in rice blast fungus (Magnaporthe oryzae) localizes on the nuclear envelope and is dispensable for M. oryzae vegetative growth and tolerance to microtubule depolymerizing agent treatment. MoMad1 plays an important role in M. oryzae infection‐related development and pathogenicity. The monopolar spindle 1 homologue in M. oryzae (MoMps1) interacts with MoMad1 through its N‐terminal domain and phosphorylates MoMad1 at Ser‐18, which is conserved within the extended N termini of Mad1s from fungal plant pathogens. This phosphorylation is required for maintaining MoMad1 protein abundance and M. oryzae full virulence. Similar to the deletion of MoMad1, treatment with Mps1‐IN‐1 (an Mps1 inhibitor) caused compromised appressorium formation and decreased M. oryzae virulence, and these defects were dependent on its attenuating MoMad1 Ser‐18 phosphorylation. Therefore, our study indicates the function of Mad1 in rice blast fungal pathogenicity and sheds light on the potential of blocking Mad1 phosphorylation by Mps1 to control crop fungal diseases.

中文翻译：

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Mps1 对 Mad1 丝氨酸 18 进行磷酸化是稻瘟病菌 Magnaporthe oryzae 发挥全部毒力所必需的

纺锤体组装检查点（SAC）蛋白在真核生物中是保守的，可在有丝分裂过程中保护染色体分离的保真度。然而，它们在植物病原真菌中的生物学功能仍然很大程度上未知。在这项研究中，我们发现稻瘟菌中的 SAC 蛋白 MoMad1（稻瘟病菌）位于核膜上并且对于米霉营养生长和对微管解聚剂处理的耐受性。 MoMad1 发挥着重要作用米霉感染相关的发展和致病性。单极纺锤体 1 同源物米霉(MoMps1) 通过其 N 端结构域与 MoMad1 相互作用，并在 Ser-18 位点磷酸化 MoMad1，该位点在真菌植物病原体 Mad1 的延伸 N 端中保守。这种磷酸化是维持 MoMad1 蛋白丰度所必需的米霉完全毒力。与 MoMad1 的缺失类似，Mps1-IN-1（一种 Mps1 抑制剂）治疗会导致附着胞形成受损并减少米霉毒力，而这些缺陷依赖于其减弱的 MoMad1 Ser-18 磷酸化。因此，我们的研究表明了 Mad1 在稻瘟病真菌致病性中的功能，并揭示了 Mps1 阻断 Mad1 磷酸化以控制作物真菌病害的潜力。