Isolation of Genes Mediating Cell-Surface Induction of Infection Structures

拟议研究的总体目标是确定调节高度特化结构（附着胞）发育的基因，这是水稻植物感染稻瘟病所必需的。稻瘟病菌是这些研究的理想选择，因为它可以在体外诱导感染结构的形成，它高度适应孟德尔和分子遗传操作，并且作为一种植物病原体具有重要意义。感染结构的形成是在分生孢子在某些疏水性基质上萌发后开始的。经过有限的伸展后，胚芽管尖端膨胀形成一个圆顶状的附着结构，即附着胞。感染菌丝从接触界面的附着胞中出现并直接穿透。Dean博士之前已经确定了在感染结构形成过程中特异性表达的两个基因，mif23和mif29。由于这些基因对环境信号有反应，他建议将启动子与可选择的标记融合，以获得调控途径基因的突变。他还发现了在不同发育阶段被阻断的突变体，并提议寻找更多。受影响的基因将通过DNA转化进行基因定位和功能补充。互补DNA将被恢复，基因克隆和表征。这些基因的鉴定对于理解和控制植物细胞表面相互作用和真菌感染的调节机制至关重要。

The overall objective of the proposed research is to identify genes that regulate the development of highly specialized structures (appressoria) that are essential for rice plant infection by Magnaporthe grisea. M. grisea is ideal for these studies since infection structure formation can be induced in vitro, the fungus is highly amenable to both Mendelian and molecular genetic manipulation and as a plant pathogen it is of major importance. Infection structure formation is initiated following conidia germination on certain hydrophobic substrata. After limited extension, the germ tube tip swells to form a dome shaped attachment structure, the appressorium. An infection hyphae emerges from the appressorium at the contact interface and penetrates directly. Dr. Dean has previously identified two genes, mif23 and mif29, that are specifically expressed during infection structure formation. Since these genes respond to environmental signals, he proposes to fuse promoters to selectable markers in order to obtain mutations in regulatory pathway genes. He has also identified mutants blocked at various stages of development and propose to search for more. The affected genes will be genetically mapped and functionally complemented by DNA transformation. Complementing DNA will be recovered and the genes cloned and characterized. The identification of these genes is paramount to understanding and controlling the mechanism(s) regulating cell surface interactions and fungal infection of plants.