Oh Yeonyee, Donofrio Nicole, Pan Huaqin, Coughlan Sean, Brown Douglas E, Meng Shaowu, Mitchell Thomas, Dean Ralph A
North Carolina State University, Center for Integrated Fungal Research, Raleigh, NC 27695-7251, USA.
Genome Biol. 2008;9(5):R85. doi: 10.1186/gb-2008-9-5-r85. Epub 2008 May 20.
Rice blast disease is caused by the filamentous Ascomycetous fungus Magnaporthe oryzae and results in significant annual rice yield losses worldwide. Infection by this and many other fungal plant pathogens requires the development of a specialized infection cell called an appressorium. The molecular processes regulating appressorium formation are incompletely understood.
We analyzed genome-wide gene expression changes during spore germination and appressorium formation on a hydrophobic surface compared to induction by cAMP. During spore germination, 2,154 (approximately 21%) genes showed differential expression, with the majority being up-regulated. During appressorium formation, 357 genes were differentially expressed in response to both stimuli. These genes, which we refer to as appressorium consensus genes, were functionally grouped into Gene Ontology categories. Overall, we found a significant decrease in expression of genes involved in protein synthesis. Conversely, expression of genes associated with protein and amino acid degradation, lipid metabolism, secondary metabolism and cellular transportation exhibited a dramatic increase. We functionally characterized several differentially regulated genes, including a subtilisin protease (SPM1) and a NAD specific glutamate dehydrogenase (Mgd1), by targeted gene disruption. These studies revealed hitherto unknown findings that protein degradation and amino acid metabolism are essential for appressorium formation and subsequent infection.
We present the first comprehensive genome-wide transcript profile study and functional analysis of infection structure formation by a fungal plant pathogen. Our data provide novel insight into the underlying molecular mechanisms that will directly benefit efforts to identify fungal pathogenicity factors and aid the development of new disease management strategies.
稻瘟病由丝状子囊菌稻瘟病菌引起，在全球范围内导致水稻年产量大幅损失。这种真菌及许多其他植物病原真菌的感染需要形成一种特殊的感染细胞，即附着胞。调控附着胞形成的分子过程尚未完全明确。
我们分析了与cAMP诱导相比，在疏水表面上孢子萌发和附着胞形成过程中全基因组基因表达的变化。在孢子萌发过程中，2154个（约21%）基因表现出差异表达，其中大多数基因上调。在附着胞形成过程中，有357个基因对两种刺激均表现出差异表达。这些基因，我们称之为附着胞共有基因，在功能上被归类到基因本体论类别中。总体而言，我们发现参与蛋白质合成的基因表达显著下降。相反，与蛋白质和氨基酸降解、脂质代谢、次生代谢及细胞运输相关的基因表达则显著增加。我们通过靶向基因敲除对几个差异调控基因进行了功能鉴定，包括一种枯草杆菌蛋白酶（SPM1）和一种NAD特异性谷氨酸脱氢酶（Mgd1）。这些研究揭示了蛋白质降解和氨基酸代谢对附着胞形成及后续感染至关重要这一此前未知的发现。
我们首次对一种植物病原真菌感染结构的形成进行了全面的全基因组转录谱研究和功能分析。我们的数据为潜在的分子机制提供了新的见解，这将直接有助于鉴定真菌致病因子，并有助于开发新的病害管理策略。
