Marker‐assisted introgression of blast resistance <i>Pi9</i> gene in Bangladeshi mega Rice variety Binadhan‐17

Abstract Blast, caused by the fungus Magnaporthe oryzae , is one of the most destructive diseases of rice worldwide and poses a major challenge to sustainable production in Bangladesh. Binadhan‐17, an elite early‐maturing, high‐yielding variety widely cultivated in Bangladesh, is highly susceptible to blast. To enhance its resistance, a blast resistance allele at the Pi9 locus from the donor parent Pongsu Seribu 2 was introgressed into the Binadhan‐17 background through marker‐assisted backcrossing (MABC). Foreground selection was carried out using the gene‐linked SSR marker RM6836, while 68 polymorphic SSR markers distributed across all rice chromosomes were employed for background selection. Four improved lines, BINA‐BR‐4‐10‐18, BINA‐BR‐4‐10‐12, BINA‐BR‐4‐10‐15, and BINA‐BR‐4‐10‐19, were successfully developed, with recurrent parent genome recovery ranging from 89% to 96.1%, the highest being in BINA‐BR‐4‐10‐12. Variation in genotype performance was observed across different locations, indicating differential responses of genotypes under diverse environmental conditions. Notably, BINA‐BR‐4‐10‐12 recorded the highest mean yield (7.68 t/ha) and maintained stable blast resistance, with disease severity remaining below 10% under artificial inoculation. These results demonstrate the effectiveness of MABC in integrating resistance genes while preserving desirable agronomic traits. The improved lines, particularly BINA‐BR‐4‐10‐12, represent promising candidates for varietal release and can contribute to the development of durable blast‐resistant rice varieties in Bangladesh.