Changes in Activity Profile of Some Antioxidant Enz ymes in Alfalfa Half-sib Families under Salt Stress

Abstract

In order to evaluate salt (NaCl) tolerance in alfa lfa ( Medicago sativa L.) half-sib families, a factorial experiment on the basis of co mpletely randomized design, with 20-25 individuals in pot (replicates) was carried out und er field conditions at the Research Station of University of Tabriz. Electrophoretic an alyses were performed by using 7.5% slab polyacrylamide gels. Two antioxidant enzymes i ncluding superoxide dismutase (SOD) and peroxidase (POX) and one common isozymic system namely esterase (EST) were stained and for each isozymic band the “densit y × area” scores onto gels were evaluated by MCID software as enzymatic activity. P lant materials consisted of 12 half- sib families that were obtained from a “polycross n ursery progeny test” in the same station, a few years ago. The applied salt stress ( 9±0.2 ds m -1 ) reduced plant height, dry weight, leaf weight and stem weight about 31.7, 37. 5, 33.7 and 34.7 percent, respectively. Significant correlations were observed between plan t height and some antioxidant isozyme activities. Salt stress increased activitie s of some SOD and POX isozymes but it was ineffective on the activity of EST. Among the f amilies, Ranger cultivar and Zaghl- aghaj and Taze-kand landraces which displayed maxim um height and other characteristics exhibited the highest increments in respect of isozyme activities, indicating that antioxidant analysis by gel electrophoresis co uld be a useful tool for salt stress tolerance studies. Keywords: Alfalfa half-sib families, Isozyme activities, Sal t stress.