Physiology of salinity tolerance in Aegilops cylindrica

Aegilops cylindrica species is one of the valuable gene pool of wheat for the understanding of salinity-tolerance mechanisms such as Na+ exclusion. Eighty-eight Ae. cylindrica genotypes were collected from saline and non-saline areas of West Iran and used in this study. Physiological and morphological traits including shoot and root fresh and dry weights, leaf MDA and H2O2 contents, leaf and root Na+, K+ and Ca2+ concentrations, K+/Na+ and Ca2+/Na+ ratio of leaves and salinity tolerance index were evaluated. Salinity stress caused significant increases in MDA and H2O2 content, Na+, Ca2+ concentrations of root and leaves, while it led to significant decline in the remaining traits. Although dry matter correlated with leaf K+/Na+ ratio (R-2 = 0.48), the regression coefficient was higher for leaf Na+ concentration (R-2 = 0.58). The results of principal component analysis revealed two components (PC1 and PC2) which totally justified 52.47 and 48.02 % of total variations of the traits in control and salinity stress conditions, respectively. Three hypersalinity-tolerant genotypes originating from the shore areas resulted from shrinking of Uremia Salt Lake and depicted by the highest PC1, PC2, dry shoot weight and leaf K+/Na+ ratio as well as the lower Na+ concentration in leaves and roots. The high Na+ exclusion ability in roots and shoots of Ae. cylindrica genotypes open up new avenues for further analyses at the cellular and molecular levels to address the role of C genome as well as the complex relations between C and D genomes to cope with hypersalinity stress via ionic homeostasis.