Study of the Activity and Isoenzyme Composition of Antioxidant Enzymes in the leaves of Barley (Hordeum vulgare L.) Genotypes Subjected to Drought Stress

Drought is one of the major factors limiting the yield and quality of crops worldwide. Barley characterized by high genetic diversity constitutes a valuable source for assessment of the responses of contrast genotypes to environmental constraints. Antioxidative metabolism plays an important role in plant responses to drought. The main aim of the study was to define variations in drought-tolerance of barley genotypes based on the obtained differencies in the levels of antioxidant enzymes during the drought stress. The activities and isoform profiles of catalase (CАТ), ascorbate peroxidase (APX), glutathione reductase (GR), and superoxide dismutase (SOD) were analyzed in four barley genotypes grown under soil drought. Drought stress caused an increase in the activities of CАТ and SOD in all studied genotypes, while APX activity decreased. The total GR activity increased substantially in genotypes K 2778 and St.Garabag 7 and decreased in №77 local and St.Pallidum 596 genotypes under severe water stress. No detectable differences were observed in the isoenzyme composition (appearance or loss of new isoenzymes) of plants subjected to soil drought in contrast to control ones. However, the bands of corresponding isoforms in electrophoretic spectra were intensified in stressed barley leaves