Improvement of bacterial blight resistance of the high yielding, fine-grain, rice variety, Gangavati sona through marker-assisted backcross breeding

Gangavati sona (GS) is a high-yielding, fine-grain rice variety widely grown in the Tungabhadra command area in Karnataka, India; however, it is susceptible to bacterial blight (BB). Therefore, the present study was conducted to improve the GS variety for BB resistance. Three BB-resistant genes ( xa5, xa13, and Xa21 ) were introgressed into the genetic background of susceptible cultivar GS through marker-assisted backcrossing (MABB) by using Improved samba Mahsuri (ISM), a popular, high-yielding, bacterial blight resistant rice variety as a donor parent. Foreground selection was carried out using gene-specific markers, viz., xa5FM ( xa5 ), xa13prom ( xa13 ), and pTA248 ( Xa21 ), while background selection was carried out using well-distributed 64 polymorphic microsatellite markers. The true heterozygote F 1 was used as the male parent for backcrossing with GS to obtain BC 1 F 1 . The process was repeated in BC 1 F 1 generation, and a BC 2 F 1 plant (IGS-5-11-5) possessing all three target genes along with maximum recurrent parent genome (RPG) recovery (86.7%) was selfed to obtain BC 2 F 2 s. At BC 2 F 2 , a single triple gene homozygote plant (IGS-5-11-5-33) with 92.6% RPG recovery was identified and advanced to BC 2 F 5 by a pedigree method. At BC 2 F 5 , the seven best entries were selected, possessing all three resistance genes with high resistance levels against bacterial blight, yield level, and grain quality features equivalent to better than GS. The improved versions of GS will immensely benefit the farmers whose fields are endemic to BB.