Marker-assisted characterization and evaluation of improved Basmati rice (Oryza sativa L.) parental lines for multiple disease resistance

Abstract

The development of improved parental lines with inbuilt resistance to major biotic stresses is a crucial step in developing promising rice hybrids since the yield advantage from the hybrids can be negated by a disease outbreak. The present study was carried out to investigate resistance to Bacterial Blight (BB), blast and sheath blight in a set of improved Basmati Putative parental lines (PPL) consisting of 59 putative maintainers and 107 restorers which were derived from multi-parent crosses involving diverse maintainers and restorer founder parents.  Among the PPLs, 71 entries displayed resistance to BB, including 32 restorers and three maintainers carrying both Xa21 and xa13 resistant alleles. Moreover, 85 genotypes exhibited resistance to blast disease, with 35 of them possessing both Pi2 and Pi54 alleles for disease resistance. Overall, 108 PPLs harboured resistant alleles for BB and blast while 60 entries were found to possess the resistant allele of one or more genes governing resistance to both blast and BB diseases and notably, 20 restorers featured all four genes (xa13, Xa21, Pi2, and Pi54). As many as 22 genotypes including nine restorers and 13 maintainers were identified as resistant to sheath blight disease. However, none of them possessed the resistant allele of the QTL, qSBR11-1. Analysis of allelic frequencies revealed an upward shift of resistant alleles in this improved Basmati rice genotype panel compared to founder parents. The amalgamation of multiple genes conferring disease resistance against diverse diseases in these parental lines can bolster hybrid breeding by developing superior hybrids with inherent resistance to these major diseases.