Dissection of Appressorium Formation in Magnaporthe grisea

*9513808稻瘟病菌院长引起稻瘟病，这是一种毁灭性的水稻病害。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。感染是由一种特殊的感染细胞--附着胞的形成引起的。这种独特组织的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信号，在细胞内传递信息以启动附着胞的形成，以及与附着胞的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。对与感染相关的形态发生的遗传和生化途径的剖析将确定新的干预目标，并可能导致开发合理的基于机制的稻瘟病菌和潜在其他真菌病原体的控制措施。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于附着胞的形成和致病是必不可少的。缺乏编码蛋白激酶A催化亚单位(CpkA)的基因的转化体不能在水稻上形成附着胞，也是非致病的。为了进一步提高我们对附着胞内通讯的认识，并确定调控附着胞形成的其他关键因素，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)鉴定和鉴定参与附着胞形成的细胞信号成分，包括G蛋白和其他在感染相关的形态发生过程中特异磷酸化的蛋白。***

*** 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. ***