Integrating phenotypic and molecular profiling for selection of promising advanced breeding lines for blast resistance in rice (Oryza sativa L.)

Rice is susceptible to several major and minor diseases, with blast disease caused by Magnaporthe oryzae being a significant constraint, leading to substantial economic losses worldwide. Exploiting genetic resistance in cultivars is a preferred strategy for managing this disease, offering an alternative to chemical control. The objective of this study was to identify advanced breeding lines (ABLs) with blast resistance, superior yield, and good grain quality using Marker-Assisted Selection (MAS). Leaf blast resistance screening revealed that 25 ABLs exhibited moderate resistance. Molecular analysis with 10 polymorphic markers linked to blast resistance genes (Pi1, Pi2, Pi9, Pi37, Pi38, Pi39, Pi54, Pita, Pitp, and Piz5) identified the highest number of positive alleles (8) in MTU1061, IR36, and SVGP-26. Additionally, seven ABLs (SVGP-1, SVGP-14, SVGP-23, SVGP-37, SVGP-38, SVGP-39, and SVGP-48) showed co-segregation of markers with blast resistance. Genetic diversity analysis revealed significant variability among the genotypes, indicating diverse genetic backgrounds. Based on their yield performance, quality traits, and resistance to blast, five parents (NLR 34449, NLR 40024, MTU 1061, MTU 3626, and IR 36) and five ABLs (SVGP-13, SVGP-16, SVGP-40, SVGP-47, and SVGP-32) were selected for further yield trials. The study identified high-yielding, blast-resistant lines with good grain quality and diverse genetic backgrounds as promising donor sources for improving blast resistance in rice breeding programs. These findings enhance the genetic base for developing resistant rice cultivars with improved agronomic traits.