The Key Lab of Plant Pathology of Hubei Province, Huazhong Agricultural University, Wuhan, 430070, Hubei, People's Republic of China.
Curr Genet. 2020 Apr;66(2):409-420. doi: 10.1007/s00294-019-01029-y. Epub 2019 Sep 5.
Ustilaginoidea virens is an important fungus causing rice false smut, a devastating disease on spikelets of rice. In this study, we identified and characterized two CMGC (CDK/MAPK/GSK3/CLK) kinase genes, UvPmk1 and UvCDC2, in U. virens. Although UvPmk1 and UvCDC2 are, respectively, homologous to Fus3/Kss1 mitogen-activated protein kinases (MAPKs) and cyclin-dependent kinases (CDKs), they all have a conserved serine/threonine protein kinase domain. The qRT-PCR analysis of the relative expression of UvPmk1 and UvCDC2 during the infection of U. virens showed that these two genes were highly expressed during infection. UvPmk1 and UvCDC2 knockout mutants exhibited no significant changes in mycelial vegetative growth but decreases in conidiation. In addition, both UvPmk1 and UvCDC2 knockout mutants showed increases in tolerance to hyperosmotic and cell wall stresses, but they, respectively, exhibited decreases and increases in tolerance to oxidative stress compared with the wild-type strain HWD-2. Pathogenicity and infection assays demonstrated the defective growth of infection hyphae and significant loss of virulence in UvPmk1 and UvCDC2 knockout mutants. Taken together, our results demonstrate that UvPmk1 and UvCDC2 play important roles in the conidiation, stress response, and pathogenicity of U. virens.
绿僵菌是引起水稻假黑粉病的重要真菌，这是一种严重危害水稻穗部的病害。在本研究中，我们鉴定并表征了绿僵菌中的两个 CMGC（CDK/MAPK/GSK3/CLK）激酶基因，UvPmk1 和 UvCDC2。虽然 UvPmk1 和 UvCDC2 分别与 Fus3/Kss1 丝裂原活化蛋白激酶（MAPKs）和细胞周期蛋白依赖性激酶（CDKs）同源，但它们都具有保守的丝氨酸/苏氨酸蛋白激酶结构域。U. virens 感染过程中 UvPmk1 和 UvCDC2 的相对表达 qRT-PCR 分析表明，这两个基因在感染过程中高度表达。UvPmk1 和 UvCDC2 敲除突变体的菌丝体营养生长没有明显变化，但产孢减少。此外，与野生型菌株 HWD-2 相比，UvPmk1 和 UvCDC2 敲除突变体的耐高渗和细胞壁胁迫能力增加，但对氧化胁迫的耐受能力分别降低和增加。致病性和感染试验表明，UvPmk1 和 UvCDC2 敲除突变体感染菌丝的生长缺陷和毒力显著丧失。总之，我们的结果表明 UvPmk1 和 UvCDC2 在绿僵菌的产孢、应激反应和致病性中发挥重要作用。
