CHANGES IN ACTIVITIES OF ANTIOXIDANT ENZYMES IN RESPONSE TO NaCl STRESS IN CALLUS CULTURES AND REGENERATED PLANTS OF SUGARCANE

Plants have a number of biochemical mechanisms to cope with salt stress. Peroxidases, Catalases and Superoxide dismutases are important antioxidant enzymes in the metabolism of reactive oxygen species (ROS) produced under salt stress. To analyze the possible role of these enzymes in developing resistance to salt stress, 60-day-old callus cultures of sugarcane (cvs. SPF 234 and HSF 240) were subjected to various NaCl levels (0-160 mM; 9 treatments). The activities of antioxidant enzymes (Peroxidase, Catalase and Superoxide dismutase) were later recorded at day 30 after ascorbic acid pretreatment. It was observed that ascorbic acid pretreatment to callus cultures as well as in vitro grown plants has a positive effect on different growth parameters tested during the study. Antioxidant enzyme activities underwent an increasing trend in response to increasing concentration of NaCl. Healthy sugarcane plants were also successfully regenerated from 120-days-old NaCl-treated callus cultures treated with various NaCl levels. It was observed that the plants regenerated from salt-treated callus cultures generally had elevated levels of antioxidant enzymes as compared to the control. Hence, it is concluded that high antioxidant enzyme activities in sugarcane cultivars induced salt stress in them which may have a better protection against reactive oxygen species. This hypothesis however needs further testing both under in vitro as well as greenhouse conditions.