Early Molecular Events in Plant-Fungus Interactions

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9816868KolattukudyThe overall objective of this research program is to elucidate the early molecular events involved in the interactions of fungi with the plant cuticle using Colletotrichum gloeosporioides and Nectria haematococca as test organisms. These interactions include the first priming stage that involves the contact of the fungal conidia with hard surface followed by germination and appressorium formation triggered by the host's chemical signals, and penetration of the cuticle and pectin barriers of the host. Early molecular events involved in the interaction of C. gloeosporioides with its host will be elucidated by cloning the genes induced by contact of the conidia with hard host surface. The Colletotrichum Hard surface Induced Protein (chip) genes will be disrupted to assess whether they are required for pathogenesis and the functions of the chip gene products will be explored. How hydroxyfatty acids of plants activate cutinase gene transcription in N. haematococca will be elucidated by cloning the transcription factors involved in the activation and by assessing their functions in yeast transformed with marker genes and the cloned transacting factors. The role of pectate lyase in pathogenesis will be tested by assessing the virulence of single and double disruptants in which pectin-inducible pelA gene and/or host-inducible pelD gene are disrupted. The host factor that is responsible for the in Planta expression of pelD gene will be purified and identified. The results of the proposed studies will provide new insights into the role of the cuticle in pathogenesis, and may help to devise new methods to control fungal diseases of plants that constitute one of the major causes of losses in food and fiber production.