Laboratory of Plant Pathology, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan.
Mol Plant Pathol. 2003 Sep 1;4(5):337-46. doi: 10.1046/j.1364-3703.2003.00182.x.
SUMMARY The rice blast fungus Magnaporthe grisea causes one of the most destructive diseases of rice. To initiate the infection of host tissues, conidia elaborate germ tubes that differentiate specialized infection structures called appressoria. Microarrays composed of 3500 cDNAs of M. grisea were prepared for the identification of genes that are specifically up- or down-regulated during appressorium formation. Gene expression in ungerminated conidia, during appressorium formation, and during mycelial growth was investigated with a novel highly sensitive dendrimer based detection system. Transcripts of 85 different genes were found to be more abundant in ungerminated conidia and/or in conidia with developing appressoria than in vegetative mycelia. Nineteen of these showed higher expression in both ungerminated conidia and developing appressoria than in mycelia, suggesting that their expression remains elevated during the early stage of fungal infection. The expression of 18 genes was higher in ungerminated conidia than in developing appressoria, indicating their possible role in the germination process or maintaining dormancy. Transcripts of 47 genes were found to be more abundant in developing appressoria than in ungerminated conidia, suggesting that their expression is induced during appressorium formation. Several of these genes, including a chitin binding protein and infection structure specific protein MIF23, were previously shown to be preferentially expressed during appressorium formation. However, the expression of many of these genes has not been reported prior to this analysis. In contrast, transcripts of 38 different genes were found to be more abundant in mycelia than in developing appressoria. A Northern blot analysis of selected genes was consistent with the microarray results. Results from this study provide a powerful resource for furthering our understanding of gene expression during infection-related morphogenesis and for the functional analysis of M. grisea genes involved in fungal infection.
摘要 稻瘟病菌（Magnaporthe grisea）引起了最具破坏性的水稻疾病之一。为了启动对宿主组织的感染，分生孢子产生分化出专门的侵染结构（称为附着胞）的芽管。为了鉴定在附着胞形成过程中特异性上调或下调的基因，我们制备了由 3500 个 M. grisea cDNA 组成的微阵列。使用一种新型的基于树突状聚合物的高灵敏度检测系统，研究了未萌发的分生孢子、附着胞形成过程中和菌丝生长过程中的基因表达。发现 85 个不同基因的转录本在未萌发的分生孢子和/或发育中的附着胞中比在营养菌丝中更为丰富。其中 19 个在未萌发的分生孢子和发育中的附着胞中比在菌丝中表达更高，这表明它们的表达在真菌侵染的早期阶段仍然升高。18 个基因在未萌发的分生孢子中的表达高于发育中的附着胞，表明它们可能在萌发过程或维持休眠中发挥作用。47 个基因的转录本在发育中的附着胞中比在未萌发的分生孢子中更为丰富，这表明它们的表达在附着胞形成过程中被诱导。其中一些基因，包括一个几丁质结合蛋白和感染结构特异性蛋白 MIF23，之前被证明在附着胞形成过程中优先表达。然而，在这项分析之前，许多这些基因的表达尚未被报道。相比之下，38 个不同基因的转录本在菌丝中比在发育中的附着胞中更为丰富。对选定基因的 Northern blot 分析与微阵列结果一致。这项研究的结果为进一步了解与感染相关的形态发生过程中的基因表达提供了有力的资源，并为参与真菌侵染的 M. grisea 基因的功能分析提供了资源。
