A putative MAP kinase kinase kinase, MCK1, is required for cell wall integrity and pathogenicity of the rice blast fungus, Magnaporthe oryzae
A putative MAP kinase kinase kinase, MCK1, is required for cell wall integrity and pathogenicity of the rice blast fungus, Magnaporthe oryzae
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DOI：
10.1094/mpmi-21-5-0525
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发表时间：
2008-05-01
影响因子：
3.5
通讯作者：
Lee, Yong-Hwan
中科院分区：
文献类型：
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作者：
Jeon, Junhyun;Goh, Jaeduk;Lee, Yong-Hwan
稻瘟病菌（Magnaporthe oryzae）的插入诱变导致了MCK1的鉴定，MCK1是一个致病性基因，预计编码与酿酒酵母（Saccharomyces cerevisiae）中BCK1同源的促分裂原活化蛋白激酶激酶激酶（MAPKKK）。对MCK1的定向破坏导致该真菌发生自溶，并对细胞壁降解酶表现出超敏性。与野生型相比，mck1产生的分生孢子数量显著减少，并且形成附着胞的速度略缓。mck1突变体的附着胞无法穿透植物组织，从而使该突变体无致病性。质壁分离测定和脂质动员监测表明附着胞壁发生了改变，可能影响了附着胞内的膨压水平。此外，mck1突变体无法在植物组织内生长。突变基因的互补恢复了其引起病害症状的能力，表明MCK1是真菌致病性所必需的。综上所述，我们的研究结果表明MCK1是一种参与维持稻瘟病菌细胞壁完整性的MAPKKK，并且响应宿主环境的细胞壁重塑对于真菌的致病性至关重要。
Insertional mutagenesis of Magnaporthe oryzae led to the identification of MCK1, a pathogenicity gene predicted to encode mitogen-activated protein kinase kinase kinase (MAPKKK) homologous to BCK1 in Saccharomyces cerevisiae. Targeted disruption of MCKI resulted in the fungus undergoing autolysis and showing hypersensitivity to cell-wall-degrading enzyme. The mck1 produced significantly reduced numbers of conidia and developed appressoria in a slightly retarded manner compared with the wild type. Appressorium of the mck1 mutant was unable to penetrate into plant tissues, thereby rendering the mutant nonpathogenic. Cytorrhysis assay and monitoring of lipid mobilization suggested that the appressorial wall was altered, presumably affecting the level of turgor pressure within appressorium. Furthermore, the mck1 mutant failed to grow inside plant tissue. Complementation of the mutated gene restored its ability to cause disease symptoms, demonstrating that MCK1 is required for fungal pathogenicity. Taken together, our results suggest that MCKI is an MAPKKK involved in maintaining cell wall integrity of M. oryzae, and that remodeling of the cell wall in response to host environments is essential for fungal pathogenesis.