Salinity tolerance of Aegilops cylindrica genotypes collected from hyper-saline shores of Uremia Salt Lake using physiological traits and SSR markers

Uremia Salt Lake, in North West Iran, has a hyper-saline water. A rare highly salinity-tolerant grass species, Aegilops cylindrica grows along its shores. Salinity tolerance of 44 genotypes of Ae. cylindrica, mainly collected from the Lake, was evaluated under control and 400 mM NaCl conditions using the physiological traits of plant height, dry weight, proline content, Na+ and K+ concentrations as well as K+/Na+ ratio. To evaluate the association between microsatellite (EST-SSR and SSR) markers and salinity tolerance, 35 primer pairs were used. Results showed a significant variation in the 44 genotypes studied in terms of their traits except for proline content. Ten most salinity-tolerant genotypes were identified based on their ability to survive, to produce the highest dry weight, and to sustain the least leaf Na+ concentration under salinity stress. The very high negative correlation found between Na+ concentration and salinity tolerance revealed the importance of individual or a combination of Na+ exclusion and excretion mechanisms contributing to the hyper-salinity tolerance of these genotypes. Clustering analysis based on marker data divided the 44 studied genotypes into two groups that were consistent with their saline and non-saline geographical areas. Results of molecular markers showed that four microsatellite markers (Xgwm312, Xwmc170, Xgwm291 and Xgwm410) generated a distinguished banding pattern in ten most salinity-tolerant genotypes. These results supported previous reports on their linkage with Na+ exclusion genes (HKT1;5 and HKT1;4) in wheat, which provided further evidence of usefulness of both genes and the linked markers to the salinity tolerance of the halophytic grass family species.