Marker-assisted pedigree breeding to enhance resistance against bacterial blight, blast, and tolerance to low soil phosphorus in the Indian elite rice cultivar MTU1121

Rice is the staple for more than half of the global population; however, its productivity is significantly impacted by various biotic and abiotic stresses. Major constraints during the whole growing season such as bacterial blight (BB), blast, and low soil phosphorus tolerance pose significant challenges to enhancing productivity. This study aimed to incorporate the Xa21 and Pi54 genes into the improved MTU1121 (carries the Pup1 gene) cultivar to confer resistance against BB and blast, respectively. An advanced breeding line, AKDRMS 21-54 (improved Akshyadhan), containing the Xa21, Pi54, and Pup1 genes/QTL, was utilized as the male parent while MTU1121 used a female parent in 2019, and true hybrids were identified using gene-linked molecular markers and subsequently self-pollinated to produce the F2 generation. Homozygous gene-carrying plants were identified within the F2 generation and further advanced up to the F5 generation through marker-assisted pedigree breeding (MAPB) followed by phenotypic selections of true to type of MTU 1121. A total of 16 homozygous improved lines harboring the Xa21, Pi54, and Pup1 genes/QTL were phenotypically evaluated for resistance against BB and blast diseases, as well as low soil phosphorus tolerance. Among these lines, three improved lines, i.e., BPT19-53-16-10, BPT19-72-10-6, and BPT19-177-17-1, demonstrated durable resistance against BB and blast diseases, while also exhibiting the tolerance to low soil phosphorus levels. These improved lines also displayed superior agro-morphological traits compared to MTU1121, suggesting their potential for further evaluation in multi-location trials for release as improved cultivars.