Drought-induced Changes in the Antioxidant System in Pisum sativum L.

Background: This study was carried out for an understanding of the antioxidant mechanisms of field pea varieties under osmotic stress conditions caused by a lack of water. The activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APx) and glutathione reductase (GR) were examined and analyzed. The gene expression levels of Cu/Zn SOD, cAPx and GR genes were also examined. Methods: Osmotic stress was stimulated using PEG 6000 with the osmotic potential of -0.1 MPa in 10 days old plant seedlings. The activity of the antioxidant enzymes was measured in the shoots and roots of pea seedlings. The gene expression levels of genes coding antioxidative enzymes were examined by the reverse transcription polymerase chain reaction (RT-PCR) technique. Arabidopsis 18S rRNA was used as endogenous control. Result: Osmotic stress changed the activities of antioxidant enzymes in the shoots and roots of pea seedlings. Varieties more tolerant to osmotic stress showed a significant increase in antioxidant activities in shoots and roots, while sensitive varieties showed a significant decrease. The results of the analysis of the expression of genes, coding for antioxidant enzymes, showed that the reaction of the tested cultivars to ROS was the result of increased expression of the tested genes in tolerant cultivars, i.e. decreased expression in sensitive cultivars.