Magnaporthe oryzae-A Cereal Killer

Blast of rice caused by Magnaporthe oryzae is one of the serious diseases of rice culture, and has been causing exhorbitant losses. The widespread occurrence of the disease and the introduction and cultivation of different rice genotypes together with their distribution in time and space predispose the pathogen population for co-evolution and emergence of variable isolates and pathotypes/races. Variability in pathogen(s) is an important component to determine the resistance of varieties to one strain and susceptibility to the other. Based on the gene-for-gene theory, differential systems consisting of resistant rice varieties and blast isolates have been developed in some countries and can be used for advanced studies in the identifications of pathogenicities of blast pathogens, estimation of resistance gene(s) is rice varieties and clarifications of these variations. DNA fingerprinting is considered an important tool for analysing population structure of M. oryzae. Fingerprints provide information needed for rational deployment of resistance genes. The lineage exclusion method consisted of breeding cultivars with those genes effective against entire lineages to achieve durable resistance against all lineages prevalent in the region. Rep-PCR fingerprinting was found to be reliable, reproducible and highly discriminatory for assessing diversity in large number of strains, especially when combined with computer-assisted data analysis.