Allele Mining and Expression Profiling of Resistance- and Avirulence- genes in Rice-Blast Pathosystem for Development of Race Non-Specific Disease Resistance
The specific objective of the NAIP under Componet 4 is to build capacity to undertake basic and strategic research in frontier areas of agricultural sciences. Present project is funded by the NAIP on "Allele Mining and Expression Profiling of Resistance- and Avirulence- genes in Rice-Blast Pathosystem for Development of Race Non-Specific Disease Resistance" under operational area of the project : Genetic Enhancement of Plants (Gene Discovery, Allele mining,... etc.
About the Project
Rice (Oryza sativa) is one of the important crops cultivated and consumed throughout the world. About 90% of rice grown in the world is produced and consumed in Asian region. Though, many high yielding varieties of rice are available, the yield potential of these varieties is considerably affected by various biotic and abiotic stresses. Among the various biotic stresses, like bacterial leaf blight, sheath blight and stem borer limiting rice productivity, rice blast caused by Magnaporthe grisea (Pyricularia oryzae) is a serious constraint in rice production at global level. Blast pathogen infects the crop in all stages of its growth, starting from nursery to grain filling stage, under favourable environmental conditions.
The major blast epidemics covering vast areas occur on a regular basis resulting in 11 to 30% crop losses annually which represents a yield loss of about 157 million tonnes world wide. In India, rice blast appears in almost all geographical regions wherever rice is grown. About 564,000 tonnes of rice is lost due to blast in Eastern India alone, nearly 50% (246,000 tonnes) in the upland ecosystem.
For the management of blast disease, use of resistant cultivars is one of the best options. However, most of the resistant cultivars remain effective only for 2-3 years because of highly variable nature of the pathogen. Thus, pyramiding of two or more genes for blast resistance would be helpful in overcoming this problem. Another strategy would be to develop a broad spectrum race-non specific resistance using latest molecular biology approaches.
Because of small genome size (389Mb) and availability of extensive data on various molecular and genetic aspects, rice is considered as a model plant for genomic studies. Many frontier areas of research in rice and rice blast pathogen genomics have started during the past few years by using the genome sequence information of both the organisms, which is in the public domain. Seven blast resistance genes have already been cloned and characterized from rice till date. We have also cloned a broad spectrum blast resistance gene Pi-kh conferring resistance to large number of strains of the blast fungus by using positional cloning approach, which is being used in rice breeding programme in the country. The sequence information of this gene along with two other broad spectrum blast resistance genes i.e. Pi-ta and Pi-z will be used in allele mining.
Using genome sequence information from M. grisea we shall mine novel alleles for Avr- genes from the pathogen. Once R- and Avr- genes are cloned, one can combine these two genes under the control of a pathogen responsive promoter for obtaining race non-specific resistance to the existing and emerging strains of M. grisea.
