COMPARATIVE STUDY OF PEROXIDASE ACTIVITY IN DICRANOPTERIS LINEARIS FACING WATER STRESS AND RECOVERY

Abstract

Drought is one of the major environmental stress affecting water potential and turgor in the plants leading to physiological imbalance. A wide variety of lower plants are known for their desiccation tolerance during their life cycle. In the present study, desiccation tolerance mechanism of Dicranopteris linearis (Burm.f.) Underw commonly called as forking fern was analyzed in terms of ROS production (H₂O₂) and the varied activity of the scavenging enzyme peroxidase. Plants exposed to desiccation-rehydration stress for different periods, i. e.., 2 d to 10 d in a controlled growth chambers and the respective controls were maintained in room temperature. Desiccation induced oxidative stress was exhibited as significant rise in the level of hydrogen peroxide (H₂O₂) and it correlated positively with duration. Subsequently, the activity of peroxidases (POX) enzyme (both cytosolic and cell wall bound) was also examined. The activity of cytosolic peroxidase was significantly higher throughout the periods of desiccation compared to wall bounded POX. The role of scavenging potential of this enzyme against ROS generated during stress is established. Histochemical analysis of peroxidase distribution by light microscopy corroborates with the activity of POX in the leaf tissue. Further, comparison of peroxidases activity revealed the insignificant level of cell wall peroxidase suggesting its noninvolvement in lignification of cell walls during stressed conditions. Here the diversion of peroxidase activity from lignification to its role as ROS scavenger is more ascertained. The present study indicates that the mechanism of desiccation tolerance in the fern is attributed to high activity of antioxidant enzymes involved in reducing the oxidation stress faced by the plant.