Fu Teng, Lee Noh-Hyun, Shin Jong-Hwan, Kim Kyoung Su
Division of Bio-Resource Sciences, BioHerb Research Institute, and Interdisciplinary Program in Smart Agriculture, Kangwon National University, Chuncheon 24341, Korea.
Plant Pathol J. 2022 Aug;38(4):345-354. doi: 10.5423/PPJ.OA.05.2022.0066. Epub 2022 Aug 1.
NADPH oxidase (Nox) complexes are known to play essential roles in differentiation and proliferation of many filamentous fungi. However, the functions of Noxs have not been elucidated in Colletotrichum species. Therefore, we set out to characterize the roles of Nox enzymes and their regulators in Colletotrichum scovillei, which causes serious anthracnose disease on pepper fruits in temperate and subtropical and temperate region. In this study, we generated targeted deletion mutants for CsNox1, CsNox2, CsNoxR, and CsNoxD via homologous recombination. All deletion mutants were normal in mycelial growth, conidiation, conidial germination, and appressorium formation, suggesting that CsNox1, CsNox2, CsNoxR, and CsNoxD are not involved in those developmental processes. Notably, conidia of ΔCsnox2 and ΔCsnoxr, other than ΔCsnox1 and ΔCsnoxd, failed to cause anthracnose on intact pepper fruits. However, they still caused normal disease on wounded pepper fruits, suggesting that Csnox2 and CsnoxR are essential for penetration-related morphogenesis in C. scovillei. Further observation proved that ΔCsnox2 and ΔCsnoxr were unable to form penetration peg, while they fully developed appressoria, revealing that defect of anthracnose development by ΔCsnox2 and ΔCsnoxr resulted from failure in penetration peg formation. Our results suggest that CsNox2 and CsNoxR are critical for appressorium- mediated penetration in C. scovillei-pepper fruit pathosystem, which provides insight into understanding roles of Nox genes in anthracnose disease development.
已知NADPH氧化酶（Nox）复合物在许多丝状真菌的分化和增殖中发挥重要作用。然而，Nox在炭疽菌属物种中的功能尚未阐明。因此，我们着手研究Nox酶及其调节因子在斯氏炭疽菌中的作用，该菌在温带、亚热带和温带地区的辣椒果实上引起严重的炭疽病。在本研究中，我们通过同源重组产生了CsNox1、CsNox2、CsNoxR和CsNoxD的靶向缺失突变体。所有缺失突变体在菌丝生长、产孢、孢子萌发和附着胞形成方面均正常，这表明CsNox1、CsNox2、CsNoxR和CsNoxD不参与这些发育过程。值得注意的是，除了ΔCsnox1和ΔCsnoxd之外，ΔCsnox2和ΔCsnoxr的分生孢子在完整的辣椒果实上不能引起炭疽病。然而，它们在受伤的辣椒果实上仍能引起正常病害，这表明Csnox2和CsnoxR对于斯氏炭疽菌中与穿透相关的形态发生至关重要。进一步观察证明，ΔCsnox2和ΔCsnoxr无法形成穿透钉，而它们的附着胞发育完全，这表明ΔCsnox2和ΔCsnoxr导致的炭疽病发育缺陷是由于穿透钉形成失败。我们的结果表明，CsNox2和CsNoxR对于斯氏炭疽菌-辣椒果实病理系统中附着胞介导的穿透至关重要，这为理解Nox基因在炭疽病发展中的作用提供了见解。
