Assessing Contrasting Wheat (Triticum aestivum L.) Cultivars Responsiveness to Salinity at the Seedling Stage and Screening of Tolerance Marker Traits

Salinity poses a significant challenge to global wheat production. The screening of wheat cultivars for salt tolerance is essential for developing new varieties resilient to salinity and advancing breeding strategies. Identifying key traits from a myriad of morphological, physiological, and molecular markers in screening studies can enhance selection efficiency and expedite the process. In this study, 16 common wheat cultivars were subjected to 0 and 150 mM NaCl stress for ten days during the seedling stage. To assess the salinity tolerance of wheat cultivars comprehensively, we employed a diverse array of morpho-physiological, biochemical, and molecular markers, coupled with multivariate analysis. Salt stress resulted in reduced germination and seedling growth across most wheat cultivars. Notably, the ‘Ikizce-96’ and ‘Demir-2000’ genotypes exhibited a higher salinity tolerance index, with the least reduction in morpho-physiological parameters. These cultivars demonstrated elevated osmoregulator proline content and enhanced activity of reactive oxygen species-scavenging antioxidant enzymes. Under 150 mM NaCl, tolerant cultivars exhibited up-regulated transcript expression levels of TaHKT1;4, TaP5CS, and TaDHN marker genes compared to salt-sensitive cultivars. The accuracy of our findings was validated through principal component analysis, hierarchical clustering analysis, and a correlation network. Proline content, glutathione reductase, catalase, and superoxide dismutase activity emerged as the most reliable indicators of salt tolerance in wheat under saline conditions. The identified salt-tolerant cultivars hold promise as donor parents in salinity tolerance breeding programs.