Molecular tools for characterization of rice blast pathogen (Magnaporthe grisea) population and molecular marker-assisted breeding for disease resistance

Abstract

Rice blast caused by the fungal pathogen, Magnaporthe grisea (anamorph: Pyricularia grisea) limits rice yield in all major rice-growing regions of the world, especially in irrigated lands and dry upland environments where predisposition factors favour disease development to epidemic proportions. Deployment of host resistance is by far the most effective means of control. The dynamic evolution of the blast fungus in response to different rice genotypes complicates breeding for blast resistance. In order to prolong the useful life of resistance genes, a knowledge of population genetics and evolutionary biology of the pathogen is r equired. The population structure and virulence composition of the blast fungus have been analysed in terms of genetic diversity, fertility and virulence characteristics. A global atlas of M. grisea and a rice blast database have been constructed based on the information. This report discusses the molecular tools that have been used for characterizing M. grisea populations in epidemic areas and describes how the molecular data generated through these methods are linked to breeding for durable blast resistance. Molecular breeding approach has been deployed in several countries across the world including India for the improvement of blast resistance in high-yielding commercial rice cultivars.