Pyramiding of Multiple Resistance Genes for Bacterial Leaf Blight and Blast Diseases in Premium Quality Rice <scp>BRRI</scp> dhan81 Through Marker‐Assisted Selection

ABSTRACT Bacterial leaf blight (BLB) and blast are the two major threats that remarkably reduce rice yield. This study was undertaken to enhance the resistance of BRRI dhan81 against these diseases. Five resistance (R) genes that conferred resistance against these diseases were introgressed in BRRI dhan81. BLB resistance genes Xa21 , xa13 and Xa4 were detected using markers MP1/MP2, xa13‐pro and pTA248, respectively, while blast resistance genes Pi9 and Pb1 were identified using markers NMSMPi9‐US2 and RM206 in the breeding population of BRRI dhan81. The F 1 to BC 3 F 6 populations were developed by successive backcrossing, selfing and foreground selection. The segregation analysis of 400 BC 3 F 2 populations confirmed the single Mendelian inheritance pattern for BLB and blast resistances. Among the final selected 30 advanced pyramided lines, 21 contained all five R genes. The BLB and blast disease scores of these lines varied from 0 to 5. Analysis of marker trait association revealed that molecular markers were negatively associated with these diseases. In multilocation trials under four agroecological zones, G13 (BR(Path)13811‐ BC 3‐17‐13‐7) exhibited the highest mean yield (8.17 t ha −1 ) across all the locations, followed by G12 (8.00 t ha −1 ) and G23 (7.72 t ha −1 ). These developed advanced pyramided lines hold the potential to be released as a resistant variety to BLB and blast diseases or may be used as a potential gene stock to incorporate with desired genes to improve the fitness and quality.