Dissection of Appressorium Formation in Magnaporthe grisea

*** 9513808稻瘟病是水稻的一种毁灭性疾病。迪恩博士对这种真菌成功感染宿主所需的特殊发育过程感兴趣。感染是由一个特殊的感染细胞——附着胞的形成引起的。这种独特组织细胞的诱导依赖于特定的环境线索。迪恩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的形成，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，而且具有实际意义。解剖感染相关形态发生的遗传和生化途径将确定新的干预目标，并可能导致基于合理机制的稻瘟病菌和潜在的其他真菌病原体控制措施的发展。先前的研究发现了许多有趣的发育突变体，并表明cAMP介导的信号转导途径对附着胞的形成和致病性至关重要。缺乏编码蛋白激酶A （cpkA）催化亚基（细胞内cAMP的主要来源）的基因的转化子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，并确定调控附着胞形成的诱导和发展的其他关键因素，我们提出了以下实验目标：1)附着胞形成所需基因的分离和鉴定，包括突变位点的DNA互补和转录调控基因的鉴定；2)介导附着胞形成的细胞信号转导成分的鉴定和鉴定，包括g蛋白和其他在感染相关形态发生过程中特异性磷酸化的蛋白。* * *

*** 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. ***