Marker-assisted backcross breeding for bacterial blight, blast and tolerance to low soil phosphorus in rice (Oryza sativa L.)

Modern highly yielding rice varieties are susceptible to various biotic stress including bacterial blight (BB), and blast and abiotic stress like phosphorus (P) starvation tolerance. To address these vulnerabilities, the present study aims to achieve gene pyramiding through marker-assisted backcross breeding (MABB) to develop improved cultivars that harbor the Xa21 (BB), Pi54 (blast resistance) and Pup1 (phosphorus starvation tolerance) genes. The parent lines, AKDRMS 21–54, (carries Xa21 and Pi54 gene, used as donor parent) and YH3 (carries Pup1 gene, used as recipient parent) were used to make a 610 BC ₂ F ₂ population. Further, this population was screened for blast, BB and low P tolerance with targeted triple gene ( Xa21  +  Pi54  +  Pup1 ) homozygous plants and total of 16 BC ₂ F ₂ lines were identified. The identified BC ₂ F ₂ four lines (YH3-22-15-19, YH3-22-15-44, YH3-22-15-234 and YH3-22-15-311) were highly resistant to blast and six lines (YH3-22-15-3, YH3-22-15-19, YH3-22-15-36, YH3-22-15-44, YH3-22-15-61 and YH3-22-15-234) were highly resistant for BB. Moreover, assessment of the enhanced BC ₂ F ₂ lines for low P tolerance unveiled a consistent decline in various growth parameters under low P conditions as well as normal P conditions. In the BC ₂ F ₂ population, reductions in most parameters studied, such as grain yield, were relatively small compared to the parents and checks cultivars, indicating their potential for thriving in low P conditions. Among the 16 BC ₂ F ₂ lines, YH3-22-15-44 possessing maximum (91.2%) RPGR (recurrent parent genome recovery) along with pyramided of target genes ( Xa21  +  Pi54  +  Pup1 ), which showed the resistant against BB and blast and high grain yield, as compared to parents and checks. This identified potential line can be utilized in multi-location trials to ensure stable performance for rice growers in future.