Table_1_Endoplasmic reticulum membrane protein MoScs2 is important for asexual development and pathogenesis of Magnaporthe oryzae.DOCX

Most secretory proteins are folded and modified in the endoplasmic reticulum (ER). In Saccharomyces cerevisiae, the absence of Scs2 protein will lead to the separation of the endoplasmic reticulum and plasma membrane, resulting in endoplasmic reticulum dysfunction, but its function is not clear in rice blast fungus or even filamentous fungus. In this study, we report the identification and characterization of MoSCS2 in the pathogenesis of the rice blast fungus Magnaporthe oryzae. Protein subcellular localization showed that MoSCS2 is mainly localized in the endoplasmic reticulum. Compared to the wild-type strain Guy11, the deletion mutant ΔMoscs2 showed a significant reduction in growth and conidiation. MoSCS2 deficiency also resulted in abnormal conidial morphology and septum formation. The ΔMoscs2 mutant shows delayed appressorium formation, and the appressorium of ΔMoscs2 mutant could not form huge turgor pressure to penetrate the host epidermal cell wall. Pathogenicity and plant leave infection assays showed that knockout of MoSCS2 significantly inhibited the expansion of the invasive hyphae in host cells, ultimately leading to the decline of pathogenicity. Moreover, MoSCS2 gene is also involved in the regulation of cell wall and endoplasmic reticulum stress response. In conclusion, MoSCS2 plays an important role in the growth, asexual production, conidia morphogenesis, infection-related morphogenesis and pathogenicity of M. oryzae.绝大多数分泌蛋白均在内质网（endoplasmic reticulum, ER）中完成折叠与修饰。在酿酒酵母（Saccharomyces cerevisiae）中，Scs2蛋白的缺失会导致内质网与质膜分离，进而引发内质网功能紊乱，但目前其在稻瘟病菌乃至丝状真菌中的功能尚不明确。本研究针对稻瘟病菌（Magnaporthe oryzae）中的MoSCS2基因，对其在致病过程中的功能开展鉴定与表征分析。蛋白质亚细胞定位实验结果显示，MoSCS2主要定位于内质网。与野生型菌株Guy11相比，敲除突变体ΔMoscs2的生长速率与产孢量均显著降低。MoSCS2功能缺失还会导致分生孢子形态异常及隔膜形成紊乱。ΔMoscs2突变体的附着胞形成过程出现延迟，且其附着胞无法产生足够的膨压以穿透宿主表皮细胞壁。致病性与植物叶片接种实验结果表明，敲除MoSCS2会显著抑制侵入菌丝在宿主细胞内的扩展，最终导致菌株致病性下降。此外，MoSCS2基因还参与调控细胞壁与内质网胁迫应答过程。综上，MoSCS2在稻瘟病菌的生长、无性繁殖、分生孢子形态发生、侵染相关形态建成及致病性调控中发挥重要作用。