Pyramiding of blast and bacterial blight resistance genes in premium quality rice variety, BRRI dhan63 through marker-assisted breeding approach

Rice blast and bacterial blight diseases are the global threat for rice production. To develop blast and bacterial blight resistant lines, two blast resistance genes ( Pi9 and Pb1 ) and three bacterial blight resistance genes ( xa5 , xa13 and Xa21 ) were pyramided in the background of premium quality rice variety BRRI dhan63 through marker-assisted backcross breeding. Pi9-US2, Pb1-US2 were used as donor parents for Pi9 and Pb1 , respectively and for xa5 , xa13 and Xa21 , IRBB60 was used as a donor parent. Three crosses were made to pyramid these genes in BRRI dhan63. F 1 to BC 3 F 6 population was developed by continuous backcrossing, selfing and foreground selection. Segregation analysis (chi-square test) of genotypic and phenotypic data of 400 BC 3 F 2 population revealed that the inheritance of blast and bacterial blight resistance followed the single gene Mendelian fashion. Finally, a total of 30 advanced lines were selected and out of them, 23 lines contained Xa4 , xa5 , Xa21 , Pi9 and Pb1 genes, six lines contained Pi9 , Xa4 and Xa21 genes and a single line contained Pi9 , Xa4 , xa5 , xa13 and Xa21 genes. Disease score of 30 advanced lines ranged from 0 to 1 for both blast and bacterial blight disease whereas in susceptible BRRI dhan63 disease score ranged from 7 to 9. Among the advanced lines, BR(Path)13,811-BC 3 -13 had the highest yield (30.41 g) per hill followed by BR(Path)13,811-BC 3 -18 (29.37 g), BR(Path)13,811-BC 3 -40 (29.08 g) and BR(Path)13,811-BC 3 -29 (28.66 g). Markers of the present study could be employed in marker-assisted selection breeding and the pyramided lines of the present study could be released as resistant varieties or used as resistant donors in the breeding program to develop blast and bacterial blight resistant varieties.