Agricultural Microbes Genome 2 Conference Agricultural Microbes Genome 2 Conference
Poster: Microbial Diversity
P02_03.html
Downy mildew, caused by the fungal pathogen, Sclerospora graminicola (sacc.) Schroet, is an economically important disease of pearl millet [Pennisetum glaucum (L.) R.Br. as it causes substantial yield losses. The variability in the pathogen has made it difficult to deploy permanent strategies for resistance. In place of the conventional methods of identification of pathogenic races using the host differentials or other pathological and morphological characteristics several molecular methods have been successfully employed in recent years. To overcome the difficulties faced in the collection of sufficient quantities S. graminicola spore samples and their transport from the pearl millet growing fields in India and Africa to the laboratory elsewhere for molecular analysis a simple method to collect the spores of from the pathogen infested fields was developed using Mira cloth. Spore samples collected by this method have been used for genetic characterization of pathogen isolates by DNA fingerprinting based on PCR. Genetic characterization of 15 isolates of S. graminicola from the different pearl millet growing areas in India that were maintained on their original host genotype and alternate hosts for several generations was carried out by Amplified fragment length polymorphism (AFLP). Of the 12 primer combinations [4 Eco RI (2+) and 6 Mse I (3+)] tested with the 15 pathogen isolates, 6 were found to be highly polymorphic. The dendrogram constructed from the similarity index data on the AFLP markers of the 15 isolates showed four major groups. Most of the isolates maintained on the susceptible pearl millet host genotype, 7042 S showed the original virulence characteristics of the different isolates thus justifying the use of 7042 S in the maintenance of the different pathogen isolates from the various pearl millet growing areas.