Modulation of Cell Components and Specific Isoforms of Antioxidant Enzymes in Safflower Under Water Stress and Recovery

Drought tolerance represents a growing threat to crop productivity. Safflower is one of the major oilseed crop enriched with various nourishing elements. In order to unravel the drought responses and recovery, a changes in cell components and specific isoforms of antioxidative enzymes in safflower (Carthamus tinctorius L. cultivar A1). Water stress (0.0%, 75%, 50% and 25% of soil moisture levels) was induced to safflower plants after 21 days of vegetative growth. After 8 days of stress imposition, plants were harvested and analysed for various parameters. A drastic decrease in the relative water content was observed during the stress and resumed the normal level after recovery. The extent of membrane damage was high under higher stress levels. These plants also showed increased levels of lipid peroxidation as evidenced from the increased malondialdehyde content, coupled with the increase in activities of antioxidant enzymes and their isoforms whereas the values in stress-recovered plants observed to be near to their respective controls. On activity gels, 12 distinct isoforms of SOD were detected; among these 10, 11 and 12 isoforms were specific under moderate and severe water stresses. Three isoforms of CAT were identified of which 2 were specific under severe water stress. In the case of POD, isoforms 2, 4, 6 and 7 were common for moderate and severe stresses whereas, POD 3 and 5 were observed only under severe stress and POD1 remained as unchanged. On recovery, the cell components and specific isoforms of antioxidative enzyme levels appeared to be that of the normal controls could be considered and used as selection criteria for improving safflower drought tolerance.