Marker-Assisted Introgression of Bacterial Blight and Blast Resistance Genes into Mega Rice Cultivar BRRI dhan28

Two major bacterial resistance (BB) genes (Xa21 and xa13) and two blast resistance genes (Pi54 and Pi1) were transferred to the popular mega rice cultivar BRRI dhan28 by marker-assisted breeding. ISM (and Xa21 and xa13) and NLR145 (Pi54 and Pi1) were used as donor parents. Maker-assisted backcrossing was performed using PCR-based gene-specific markers for target genes and a set of 60 polymorphic SSR primers for background selection. The BC1F1 plants from two crosses had 73 and 72% gene recovery of BRRI dhan28, respectively, and were crossed to produce ICF1 and, after that, selfed to produce 120 ICF2 plants. Among ICF2 plants, seven homozygous plants (xa13xa13Xa21Xa21Pi54Pi54Pi1Pi1) were identified with 80% recovery of the parental genome. Seven ICF2 showed high resistance to blast and bacterial blight diseases. Several ICF2 lines with high levels of resistance to BB and blast with yield, seed quality and plant type similar to BRRI dhan28 were identified and advanced for evaluation and further selection.