Abstract:
Zagros (drought tolerant) and Pishtaz (drought susceptible) cultivars were classified on
the basis of shoot dry weight and were used as plant material in this study. Total
chlorophyll, carotenoids, antocyanins, proline, soluble sugar contents, lipid peroxidation,
antioxidant enzyme activities and protein patterns were determined. Seedlings of wheat
genotypes were grown in nutrient solution cultures under 16 h d-1 period at room
temperature. With the decrease in osmotic potential, total chlorophyll initially increased
but then decreased in the tolerant cultivar. The amount of total carotenoids and
antocyanins in both cultivars increased in response to drought stress. However, the
increase was only significant (P< 0.05) at some osmotic potentials. The increase was more
pronounced in the tolerant cultivar. Soluble sugars and proline increased significantly in
both cultivars, but were higher in the tolerant one. The sensitive cultivar showed higher
rates of lipid peroxidation as compared to the tolerant cultivar. Antioxidant enzymes
activities increased with the decrease in osmotic potential in both cultivars. The tolerant
cultivar exhibited a higher antioxidant activity compared to the sensitive one. SDS-PAGE
showed new protein bands under water stress. These results indicated that proline,
soluble sugars contents and antioxidant enzyme activities are part of the defense
mechanisms which confer water deficit tolerance to wheat cultivars. APX= Ascorbate
peroxidase; CAT= Catalase; GR= Glutathione reductase; MDA= Malondialdehyde;
ROS= Reactive oxygen species, SOD= Superoxide dismutase.
Keywords: Antioxidant, Compatible solute, Water stress, Wheat cultivars.
