Molecular characterization of blast resistance genes in elite rice cultivars using SSR markers

Abstract:

In the hills of Himachal Pradesh, rice blast caused by Magnaporthe oryzae can wipe out 40-80% of a crop in epidemic years, yet most cultivars grown in the region have never been screened for known resistance genes at the molecular level. This research characterized eight elite rice cultivars from the Himachal Pradesh breeding programme for the presence of five blast resistance genes (Pi2, Pi9, Pi-ta, Pib, Pi-kh) using six linked SSR markers, and validated the marker data against phenotypic blast reactions at Chaudhary Sarwan Kumar HP Agricultural University, Palampur, during kharif 2022-23. HPR-2143 and VL-Dhan-86 carried the highest number of resistance-linked alleles (6 out of 6 markers positive) and scored 8.4 and 7.8 on a 1-9 blast resistance scale in detached-leaf assays against five local Magnaporthe isolates. Pusa-1121 carried only 2 positive alleles and was the most susceptible (score 3.2). Marker-phenotype association was significant for all six SSRs (Chi-square, p< 0.05). These results identify HPR-2143 and VL-Dhan-86 as donor sources for blast resistance gene pyramiding in the Himachal Pradesh rice improvement programme.