State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China.
Hubei Key Lab of Plant Pathology, and College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China.
Mol Plant Pathol. 2021 Aug;22(8):969-983. doi: 10.1111/mpp.13074. Epub 2021 May 25.
Magnaporthe oryzae causes rice blast disease, which seriously threatens the safety of food production. Understanding the mechanism of appressorium formation, which is one of the key steps for successful infection by M. oryzae, is helpful to formulate effective control strategies of rice blast. In this study, we identified MoWhi2, the homolog of Saccharomyces cerevisiae Whi2 (Whisky2), as an important regulator that controls appressorium formation in M. oryzae. When MoWHI2 was disrupted, multiple appressoria were formed by one conidium and pathogenicity was significantly reduced. A putative phosphatase, MoPsr1, was identified to interact with MoWhi2 using a yeast two-hybridization screening assay. The knockout mutant ΔMopsr1 displayed similar phenotypes to the ΔMowhi2 strain. Both the ΔMowhi2 and ΔMopsr1 mutants could form appressoria on a hydrophilic surface with cAMP levels increasing in comparison with the wild type (WT). The conidia of ΔMowhi2 and ΔMopsr1 formed a single appressorium per conidium, similar to WT, when the target of rapamycin (TOR) inhibitor rapamycin was present. In addition, compared with WT, the expression levels of MoTOR and the MoTor signalling activation marker gene MoRS3 were increased, suggesting that inappropriate activation of the MoTor signalling pathway is one of the important reasons for the defects in appressorium formation in the ΔMowhi2 and ΔMopsr1 strains. Our results provide insights into MoWhi2 and MoPsr1-mediated appressorium development and pathogenicity by regulating cAMP levels and the activation of MoTor signalling in M. oryzae.
稻瘟病菌引起稻瘟病，严重威胁粮食生产安全。了解附着胞的形成机制，这是稻瘟病菌成功感染的关键步骤之一，有助于制定有效的稻瘟病防治策略。在本研究中，我们鉴定了 MoWhi2，即酿酒酵母 Whi2（威士忌 2）的同源物，作为控制稻瘟病菌附着胞形成的重要调节剂。当 MoWHI2 被破坏时，一个分生孢子会形成多个附着胞，致病性显著降低。通过酵母双杂交筛选实验，鉴定出一个假定的磷酸酶 MoPsr1 与 MoWhi2 相互作用。ΔMopsr1 敲除突变体表现出与 ΔMowhi2 菌株相似的表型。与野生型（WT）相比，ΔMowhi2 和 ΔMopsr1 突变体在亲水表面上都能形成附着胞，并且 cAMP 水平升高。当雷帕霉素（TOR）抑制剂雷帕霉素存在时，ΔMowhi2 和 ΔMopsr1 突变体的分生孢子每个分生孢子形成一个附着胞，与 WT 相似。此外，与 WT 相比，MoTOR 的表达水平和 MoTor 信号激活标记基因 MoRS3 增加，表明 MoTor 信号通路的不当激活是 ΔMowhi2 和 ΔMopsr1 菌株附着胞形成缺陷的重要原因之一。我们的研究结果为 MoWhi2 和 MoPsr1 介导的附着胞发育和致病性提供了新的认识，通过调节 cAMP 水平和 MoTor 信号的激活。
