Morphological and molecular genetic variation in wheat for salinity tolerance at germination and early seedling stage

Abstract

Salinity is one of the major constraints to wheat production. Salt affected soils can be better utilized by developing and growing salt tolerant wheat varieties. Genetic diversity for salt tolerance is a prerequisite for developing salt tolerant wheat varieties. Therefore, the present study was conducted to evaluate the level of genetic diversity among 172 (123 Pakistani and 49 exotic) wheat genotypes for salinity tolerance at germination and early seedling stage. All the genotypes were first tested at 200 mM NaCl stress. Based on the results, 34 genotypes were selected and subsequently tested at 250 mM and 300 mM NaCl stress. Genetic variation for salt tolerance existed in the studied wheat genotypes. Plumule growth was affected more than radicle growth at higher salinity levels. Based on salt tolerance index, 18 accessions were identified as salt tolerant at 200 mM NaCl stress. Egyptian accession 11466 was the most salt tolerant at 250 mM NaCl stress, whereas Pakistani accession 11299 and Egyptian accession 11466 were the most salt tolerant at 300 mM NaCl stress. Genetic similarity coefficients based on RAPD marker data ranged from 0.38 to 0.95. RAPD primer OPA 2 produced a unique fragment of 1000 bp, whereas OPF 13 generated two fragments of 1200 bp and 1400 bp only in some tolerant genotypes. Genetic similarity coefficients for SSR markers ranged from 0.45 to 0.95. Both RAPD and SSR markers revealed genetic variation in the studied genotypes. The salt tolerant landraces identified in this study could be used as parents to incorporate salt tolerance in future wheat cultivars. The unique DNA fragments observed in this study should be further investigated in segregating populations to determine their usefulness in Marker assisted selection for salt tolerance in wheat.