Salinity stress responsive leaf proteins in alfalfa (Medicago sativa L.)

Salinity stress is one of the most harmful abiotic stresses that affect agronomical, physiological and biochemical processes in crop plants. In order to evaluate the effect of salinity stress on alfalfa (Bami ecotype) leaf proteins based on two-dimensional gel electrophoresis, an experiment was conducted with two salinity treatments (0 and 200 mM NaCl) and six replications under hydroponic cultural system. Salinity stress decreased fresh and dry weight of alfalfa about 24.5 and 39.5 percent, respectively. Proteome analysis was carried out on the leaf tissue using three replications. Fourteen repeatable protein spots had significant change in expression under salt stress. Probabilistic identification of proteins from the data bank was performed by isoelectric point and molecular weight. Nine proteins showed significant up-regulation and five proteins had down regulation. Candidate proteins were among the proteins involved in the defense system, regulation, metabolic pathways, nitrogen fixation and canalization. Higher abundance of trehalose-phosphate phosphatase 2, involved in regulation, and also uracil phosphoribosyl transferase lastic and β-hydroxyisobutyryl-CoA hydrolase 1, involved in the energy metabolism, demonstrated the important function of these proteins under salinity stress. It seems that the alfalfa plant manages to reduce the adverse effects of salinity through the candidate proteins identified in this investigation.