Abstract A wild type Magnaporthe oryzae CY2 with normal growth and sporulation but weak pathogenicity is not virulent to more than over 1000 rice cultivars. Based on the transformant library of M. oryzae CY2 by Agrobacterium tumefaciens-mediated transformation (ATMT), we screened a transformant T23 with normal infectious hyphae and pathogenicity to rice line IRBL-19. Co-segregation and southern blotting suggested that T-DNA is inserted with single copy, and pathogenicity may require the mutated gene MoNFR. Bioinformatics analysis predicted that the gene MoNFR encoded a putative NADPH-ferrihemoprotein reductase with an indole amine 2,3-dioxgyenase (IDO) domain, a flavin adenine dinucleotide binding domain (FAD_binding domain), a nicotinamide adenine dinucleotide binding domain (NAD_binding domain) and a cytochrome-b5 domain. Vectors were constructed to knock-out the target gene. Two mutants with MoNFR disruptant were obtained from the wild type strain CY2 by targeted gene replacement with hygromycin B phosphotransferase (HPH) gene. Compared with strain T23 and CY2, the MoNFR mutants showed no significant difference in colony morphology, growth rate and mycelium color but conidia produced in culture were 4.5–5 times more and higher percentage of appressorial and infectious hyphae formation was observed on onion epidermis. They retain the pathogenicity to IRBL-19, and are similar in virulence to strain T23. These results indicate that MoNFR plays a key role in the pathogenicity of M. oryzae.

中文翻译：

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编码假定的 NADPH-铁血蛋白还原酶的 MoNFR 是稻瘟病菌的致病性所必需的

摘要 野生型稻瘟病菌CY2生长正常，产孢正常，但致病力较弱，对1000多个水稻品种无毒力。基于根癌农杆菌介导转化（ATMT）的米根霉CY2转化体文库，我们筛选了具有正常感染性菌丝和对水稻品系IRBL-19致病性的转化体T23。共分离和Southern印迹表明T-DNA以单拷贝插入，致病性可能需要突变基因MoNFR。生物信息学分析预测，基因 MoNFR 编码一个推定的 NADPH-铁血蛋白还原酶，具有吲哚胺 2,3-二氧乙烯酶 (IDO) 结构域、黄素腺嘌呤二核苷酸结合结构域（FAD_binding 结构域）、烟酰胺腺嘌呤二核苷酸结合结构域（NAD_binding domain）和细胞色素-b5 结构域。构建载体以敲除靶基因。通过用潮霉素 B 磷酸转移酶 (HPH) 基因进行靶向基因置换，从野生型菌株 CY2 中获得了两个具有 MoNFR 破坏体的突变体。与菌株 T23 和 CY2 相比，MoNFR 突变体在菌落形态、生长速率和菌丝体颜色方面没有显着差异，但培养中产生的分生孢子多 4.5-5 倍，并且在洋葱表皮上观察到更高的附着和感染菌丝形成百分比。它们保留了对 IRBL-19 的致病性，毒力与 T23 毒株相似。这些结果表明，MoNFR 在米曲霉的致病性中起关键作用。通过用潮霉素 B 磷酸转移酶 (HPH) 基因进行靶向基因置换，从野生型菌株 CY2 中获得了两个具有 MoNFR 破坏体的突变体。与菌株 T23 和 CY2 相比，MoNFR 突变体在菌落形态、生长速率和菌丝体颜色方面没有显着差异，但培养中产生的分生孢子多 4.5-5 倍，并且在洋葱表皮上观察到更高的附着和感染菌丝形成百分比。它们保留了对 IRBL-19 的致病性，毒力与 T23 毒株相似。这些结果表明，MoNFR 在米曲霉的致病性中起关键作用。通过用潮霉素 B 磷酸转移酶 (HPH) 基因进行靶向基因置换，从野生型菌株 CY2 中获得了两个具有 MoNFR 破坏体的突变体。与菌株 T23 和 CY2 相比，MoNFR 突变体在菌落形态、生长速率和菌丝体颜色方面没有显着差异，但培养中产生的分生孢子多 4.5-5 倍，并且在洋葱表皮上观察到更高的附着和感染菌丝形成百分比。它们保留了对 IRBL-19 的致病性，毒力与 T23 毒株相似。这些结果表明，MoNFR 在米曲霉的致病性中起关键作用。在洋葱表皮上观察到 5-5 倍和更高百分比的附着和感染菌丝形成。它们保留了对 IRBL-19 的致病性，毒力与 T23 毒株相似。这些结果表明，MoNFR 在米曲霉的致病性中起关键作用。在洋葱表皮上观察到 5-5 倍和更高百分比的附着和感染菌丝形成。它们保留了对 IRBL-19 的致病性，毒力与 T23 毒株相似。这些结果表明，MoNFR 在米曲霉的致病性中起关键作用。