Morphological Screening and SalTol Region Based SSR Markers Analysis of Rice (Oryza sativa) Genotypes for Salinity Tolerance at Seedling Stage

Rice production is greatly limited by high level of soil salinity around the world. To overcome this major abiotic constraint, different strategies have been adopted for the development of salt tolerant rice varieties. In present study, tolerance potential of 63 rice genotypes was evaluated at seedling stage under different levels of salt stress (0, 50, 100 and 150 mM). Among screened genotypes, six were found tolerant, 37 moderately tolerant and 20 were sensitive under tested levels of salt stress. Tolerant genotypes showed less reduction in root shoot length, fresh weight and dry weight, compared with FL478 (positive control). Sensitive genotypes showed similar to 90% reduction in all growth parameters at 150 mM Selected genotypes, representing all three groups, were further assessed for salinity tolerance at molecular level using 21 simple sequence repeat (SSR) markers, residing within SalTol QTL region on chromosome 1 and 19 SSR markers were found polymorphic among salt tolerant and sensitive genotypes. Cluster analysis based on SSR markers, grouped genotypes into three clusters as sensitive, tolerant and moderately tolerant. However, population structure analysis combined tolerant and moderately tolerant genotypes in one set, as both had close genetic similarity in response to salinity and placed sensitive genotypes into separate group. Our results revealed that tolerant genotypes can be identified on the basis of growth parameters like root shoot length, root shoot fresh and dry weight at seedling stage under salt stress conditions. Moreover, molecular markers were able in differentiating the identified salt tolerant and sensitive genotypes. The identified salt tolerant genotypes might also serve as potential donors for the introgression salt tolerant genes/QTLs into high yielding, Basmati and non-Basmati rice varieties. (C) 2019 Friends Science Publishers