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.

中文翻译：

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两种蛋白激酶UvPmk1和UvCDC2在稻曲霉菌Ustilaginoidea virens的分生，胁迫反应和致病性中具有重要功能。

Ustilaginoidea virens是导致水稻假曲丝的重要真菌，这是水稻小穗上的毁灭性疾病。在这项研究中，我们确定了U.virens中的两个CMGC（CDK / MAPK / GSK3 / CLK）激酶基因UvPmk1和UvCDC2。尽管UvPmk1和UvCDC2分别与Fus3 / Kss1丝裂原激活的蛋白激酶（MAPK）和细胞周期蛋白依赖性激酶（CDK）同源，但它们都具有保守的丝氨酸/苏氨酸蛋白激酶结构域。在U. virens感染期间UvPmk1和UvCDC2相对表达的qRT-PCR分析表明，这两个基因在感染期间高度表达。UvPmk1和UvCDC2敲除突变体的菌丝营养生长没有显着变化，但分生孢子减少。此外，与野生型菌株HWD-2相比，UvPmk1和UvCDC2敲除突变体均显示出对高渗胁迫和细胞壁胁迫的耐受性增加，但它们分别显示出对氧化胁迫的耐受性下降和升高。致病性和感染分析表明，UvPmk1和UvCDC2敲除突变体中感染菌丝的生长缺陷和毒力显着降低。两者合计，我们的结果表明，UvPmk1和UvCDC2在U. virens的分生，应激反应和致病性中起重要作用。致病性和感染分析表明，UvPmk1和UvCDC2敲除突变体中感染菌丝的生长缺陷和毒力显着降低。两者合计，我们的结果表明，UvPmk1和UvCDC2在U. virens的分生，应激反应和致病性中起重要作用。致病性和感染分析表明，UvPmk1和UvCDC2敲除突变体中感染菌丝的生长缺陷和毒力显着降低。两者合计，我们的结果表明，UvPmk1和UvCDC2在U. virens的分生，应激反应和致病性中起重要作用。