Marker-assisted backcross breeding for bacterial blight resistance in basmati rice

Abstract:

Imagine a farmer planting the finest Basmati rice only to watch bacterial blight destroy 40% of the crop before harvest—a scenario that plays out annually in South and West Asian rice belts. This research used marker-assisted backcross breeding (MABB) to transfer two bacterial blight resistance genes, Xa21 and xa13, from the donor line IRBB60 into the elite Basmati variety Pusa Basmati 1121. Three rounds of backcrossing followed by three generations of selfing were completed at Fars University of Agriculture, Shiraz, Iran, between January 2022 and August 2024. Foreground selection with gene-linked SSR markers confirmed the presence of both resistance genes in 87 of 186 BC3F1 plants. Background selection using 86 genome-wide markers showed 97.2% recovery of the recurrent parent genome by the BC3F4 generation. Selected lines scored 1.7 on a 0-9 severity scale versus 7.4 for Pusa Basmati 1121, representing a 77.0% reduction in disease severity. Grain quality traits—kernel length, aroma, and amylose content—were statistically equivalent to the recurrent parent.