Dissection of Appressorium Formation in Magnaporthe grisea

* 9513808迪恩 稻瘟病菌引起稻瘟病，一种毁灭性的水稻疾病。迪恩博士对这种真菌成功感染宿主所需的专门发育过程感兴趣。感染是通过形成专门的感染细胞（附着胞）而启动的。这种独特的组织细胞的诱导依赖于特定的环境线索。Dean博士的研究目标是了解真菌如何识别这些线索，在细胞内传递信息以启动附着胞形成以及与附着胞发育和功能相关的生化机制。这些调查的结果不仅将提供基本信息，而且将具有实际意义。对感染相关形态发生的遗传和生化途径的剖析将确定新的干预靶点，并可能导致基于M.稻瘟病菌和潜在的其它真菌病原体。先前的研究鉴定了一些有趣的发育突变体，并表明cAMP介导的信号转导途径是附着胞形成和致病性所必需的。 缺乏编码蛋白激酶A（cpkA）催化亚基（胞内cAMP的主要来源）的基因的转化体不能在水稻上形成附着胞并且是非致病性的。为了进一步提高我们对细胞内通讯的认识并鉴定调节附着胞形成的诱导和发育的其他关键元件，提出了以下实验目标：1）附着胞形成所需基因的分离和表征，包括突变基因座的DNA互补和转录调控基因的鉴定，2）鉴定和表征介导附着胞形成诱导的细胞信号传导组分，包括G蛋白和在感染相关形态发生期间特异性磷酸化的其他蛋白。 ***

*** 9513808 Dean Magnaporthe grisea causes rice blast, a devastating disease of rice. Dr. Dean is interested in a specialized developmental process required by this fungus for successful infection of its host. Infection is initiated by the formation of a specialized infection cell, the appressorium. The induction of this uniquely organized cell is dependent on specific environmental cues. The goal of Dr. Dean's research is to understand how the fungus recognizes these cues, relays the information within the cell to initiate appressorium formation as well as the biochemical machinery that is associated with appressorium development and function. Results from these investigations will not only provide fundamental information but will have practical relevance. Dissection of the genetic and biochemical pathways central to infection related morphogenesis will identify new targets for intervention and may lead to the development of rational mechanism based control measures for M. grisea and potentially other fungal pathogens. Previous research identified a number of interesting developmental mutants and showed that a cAMP mediated signal transduction pathway is essential for appressorium formation and pathogenicity. Transformants lacking the gene encoding the catalytic subunit of protein kinase A (cpkA), the principle source of intracellular cAMP, are unable to form appressorium on rice and are nonpathogenic. To further advance our knowledge of intracellular communication and identify other key elements regulating the induction and development of appressorium formation the following experimental objectives are proposed: 1) Isolation and characterization of genes required for appressorium formation, including DNA complementation of mutant loci and identification of transcriptionally regulated genes, 2) Identification and characterization of cellular signaling components mediating the induction of appressorium formation, including G-proteins and other proteins specifically phosphorylated during infection related morphogenesis. ***