Seasonal variation of antioxidant enzymatic responses in the desiccation-tolerant bryophyte Syntrichia ruralis (Hedw.) Web. & Mohr.

Abstract

Bryophytes are poikilohydric organisms that can be used as model plants to study desiccation tolerance mechanisms. The main objective of this study was to examine the activities of the antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT) and guaiacol peroxidase (POD) in the rehydrated and desiccated states in Syntrichia ruralis (Hedw.) Web. & Mohr. from two slopes, one North-east (NE) and one South-west (SW) facing and collected in different seasons. Our results showed seasonal variation in the enzymatic activities of APX, CAT and POD between the slopes in both the rehydrated and desiccated states. The mean value of all the activities of APX, CAT and POD and MDA contents (a measure of lipid peroxidation) tended to be higher in moss cushions collected from the NE compared to the SW facing slopes except in summer season. The mean values of all enzymatic activities were higher in desiccated states as compared with rehydrated states. Protein content has lower values in summer and winter season. Differences in the antioxidant activities of the mosses growing on the two slopes may reflect adaptations to desiccation stress.