Molecular Characterization of Advanced Breeding Lines For Blast and Bacterial Leaf Blight Resistance in Rice (Oryza Sativa L.)

MTU1010 (Cottondora Sannalu) is one of the popular variety released by Andhra Pradesh Rice Research Institute (APRRI), Maruteru. It is a mega variety occupied maximum area in India and grown in many parts of Telangana particularly during Rabi season. It is a short duration, high yielding, long slender, BPH tolerant rice variety but it is highly susceptible to blast and bacterial blight diseases, which are endemic to many rice growing areas in India. Akshayadhan NIL (RP 6132) possessing major broad-spectrum resistance genes against blast (Pi54) and bacterial leaf blight (Xa21) was used as a donor to improve MTU1010 NIL (RP5973-20-9-8-24-12-7), through marker-assisted pedigree breeding combined with phenotype-based selection for agro-morphological traits specific for MTU1010 NIL. In the present investigation, Advanced breeding lines (F7 generation) were screened through foreground selection for confirmation of presence of target trait specific genes viz., for blast (Pi54) and bacterial blight (Xa21). Foreground selection was carried out with co-dominant markers pTA248 and Pi54-MAS for checking the presence of Pi54 and Xa21 respectively. Out of 50 advanced breeding lines, it was found that 35 lines possessing resistant allele of Pi54 gene and 34 lines possessing resistant allele of Xa21 gene. 22 breeding lines possessing both Pi54 and Xa21 resistant alleles. The same 50 advanced breeding lines were screened for BB resistance in the field and for blast in Uniform blast nursery at RARS, Jagtial during Rabi 2020-21. Out of 50 lines screened for both BB and blast, 35 breeding lines showed resistance against blast disease, and 34 breeding lines showed resistance against BB disease. 22 lines showed resistance to both blast and bacterial leaf blight disease. Six breeding lines exhibited good performance with the high level of resistance to the diseases viz., blast and bacterial blight and possess high grain yield and grain quality better than MTU1010 NIL. The results obtained in the present study indicated the success of marker-assisted pedigree breeding coupled with phenotypic selection.