Phenotypic and genotypic screening of rice genotypes at seedling stage for salt tolerance.

Abstract

Selection for salinity tolerant genotypes of rice based on phenotypic performance alone is less reliable and will delay in\nprogress in breeding. Recent advent of molecular markers, microsatellites or simple sequence repeats (SSRs), have been\nuseful in finding salt tolerant rice genotypes. Three selected SSR markers already known to be polymorphic, viz., RM7075,\nRM336 and RM253, were used to evaluate rice genotypes for salt tolerance. Phenotypic and genotypic evaluation for\nsalinity tolerance was done at the seedling stage. Phenotyping was done in hydroponic system using salinized (EC 12 dS/m)\nnutrient solution following IRRI standard protocol. Large variation in salinity tolerance among the rice germplasms was\ndetected. Salt stress (EC 12 dS/m) reduced seedling height by 19.0% and total dry matter of tolerant lines by 40.6%,\nwhereas, total dry matter of susceptible lines were reduced by 46.0-73.5%. All the tested markers were polymorphic and\nwere able to discriminate salt tolerant genotypes from susceptible. The genotypes having similar banding pattern with\nPokkali were considered as salt tolerant. Markers RM7075, RM336 and RM253 identified eight, nine and seven salt tolerant\ngenotypes, respectively. Through phenotypic and genotypic study, three genotypes viz., Pokkali, TNDB-100 and THDB\nwere identified as salt tolerant rice genotypes. These SSR markers might have sequence homology with salt tolerant rice\ngenotypes and consequently the markers could able to identify salt tolerant rice genotypes from susceptible ones