QUANTITATIVE RT-PCR ANALYSIS OF PHYTOPHTHORA SPECIFIC GENES EXPRESSED DURING PHYTOPHTHORA CAPSICI?PIPER COLUBRINUM INTERACTION

The genus Phytophthora, contains destructive plant pathogens that cause enormous economic damage to many important crop species. These funguses like oomycete pathogens employ diverse mechanisms to break down plant defence mechanism. An understanding of the process by which these pathogens colonize their host is essential to develop appropriate disease management strategies. Phytophthora capsici which causes foot rot, is a serious disease in black pepper growing areas throughout the world and P.colubrinum, a distantly related species is highly resistant to the pathogen infection. The genes selected in this particular study, are responsible for the production of pathogen-derived molecules which play an important role in the process of colonization of the pathogen on the particular host, as well as in modulating defence responses in the particular host. Quantitative RT-PCR was employed to assess the level of expression of some of the genes of P.capsici like Glycoside hydrolase, NPP 1, RXLR and Pectatelyase, found to be expressed during P.capsici-P.colubrinum interaction. Glycoside hydrolase and RXLR genes showed high levels of expression during early stages of infection (up to 16 hpi), whereas the NPP1 gene showed maximum expression at later stages of infection (at 72 hpi). Pectatelyase gene showed high level of expression at early stages of infection but was then down regulated during the later stages of infection. The expression of these genes during initial phase of infection gives an idea about the importance of these genes during host colonization and in defence response of the plant to the particular pathogen