Molecular analysis of QTLs associated with resistance to brown spot in rice (Oryza sativa L.)

Abstract

Helminthosporiosis or brown spot disease is widely distributed and is known to cause heavy yield losses in rice. In present investigation, a set of 154 doubled haploid (DH) lines derived from a cross between CT 9993-5-10-1M and IR 62266-42-6-2 was used to identify quantitative trait loci (QTLs) for brown spot disease. DH lines along with parents were planted in two different soil environments with two replications each in RCBD and evaluated for the brown spot resistance. We have identified total 10 QTLs for brown spot resistance using MAPMAKER/QTL 1.1 distributed over the eight chromosome of rice. Out of 10 QTLs, four were consistently discovered in both the soil types. The QTL BSq4.1 and BSq11.1 located on the chromosome 4 and 11 were identified in both the environment with higher LOD score and phenotypic variance and will be good candidates for fine mapping and positional cloning studies.