Stable quantitative trait locus (QTL) for sheath blight resistance from rice cultivar CR 1014

Sheath blight disease of rice causes substantial crop losses and resistance sources are rare. A moderately resistant genotype CR 1014 was identified and hybridized with highly susceptible genotype Swarna-Sub1. In the F 2 and F 2:3 generations, three QTLs ( qShB-1.1, qShB-1.2 and qShB-1.3 ) were mapped in chromosome-1. In F 5 generation of the same cross and F 4 generation of an alternative mapping population (Tapaswini/CR 1014), only the major QTL qShB-1.1 was recorded consistently with high LOD score (> 5.0). This stable QTL was co-localized with qShB1 reported earlier from Oryza nivara . A typical leucine rich repeat (LRR) motif containing gene ( LOC_Os01g65650 ) and a chitin-inducible gibberellin-responsive protein coding non-LRR gene ( LOC_Os01g65900 ) located within qShB-1 . 1 with high expression levels in leaf and shoot were predicted as putative candidate genes among others. Nearly 27.8% reduction in relative lesion height was recorded among several near isogenic lines of Swarna-Sub1 carrying the QTL region from CR 1014.