Identification of Quantitative Trait Loci for Leaf Blast Resistance of Rice (Oryza sativa L.)

Blast is one of the economically important diseases of rice. Quantitative trait loci (QTL) analysis for partial resistance to leaf blast disease was carried out using 122 RIL population from the cross between Danteshwari (highly susceptible) and Dagad deshi (resistant) in blast endemic area of Ambikapur, north Chhattisgarh, India during wet season, 2013. Analysis indicated that approximately normal distribution of RILs for the trait leaf blast resistance. A linkage map was constructed from 122 RILs using 162 polymorphic SSR markers. Composite interval mapping was employed to identify QTLs. Five QTLs such as “qLB12.1”, “qLB12.2”, “qLB12.3”, “qLB12.4” and “qLB10.1” were identified for leaf blast resistance using RIL population on chromosomes 12 and 10, respectively. The QTLs, “qLB12.2”, “qLB12.3”, “qLB12.4” mapped both seedling and tillering stages of RIL population of rice. The LOD score and phenotypic variation explained by each QTL ranged from 6.898-3.021 and 15.86 - 56.24%, respectively. The qLB12.2 was identified for both stage and found stable across the life of rice for leaf blast resistance. The resistance loci mapped to chromosome 10 specific to second replication. The QTLs identified could be used as a genetic resource in improvement of rice varieties for blast resistance. These findings laid the foundation for the development of a marker-assisted scheme for improving majority of rice varieties that are susceptible to blast and useful for fine mapping studies.