A combination of morphological, biochemical and structural responses is required for desiccation tolerance in...

The innate ability for desiccation tolerance in Selaginella repanda was determined by evaluating the physiological and biochemical modifications that occur during water loss and gain, in different stages namely, hydrated (H), desiccation (D), and rehydrated stages (R). Herbarium JCB and rbcl gene barcoding were used for its identification. In the desiccated stage, relative water content (RWC) was 8.3% which regained to 96.8% in R stage. Leaf water potential decreased to -3.8MPa in D stage. Scanning electron microscopic images shows significant modification of stomata and cell in D and R stages. Scanning electron microscopic images shows significant modification of stomata and cell in D and R stages. Total chlorophyll (0.9-fold) and carotenoids (0.7-fold) concentrations were found to be reduced during D stage, when compared to H stage. Concentration of anthocyanin (1.14-fold), proline (2.9-fold) and lipid peroxidation (1.9-fold) were found to be significantly high in D stage. Carbon dioxide exchange rate (- 0.6 µ mol m^-2 s^-1) was negative during D stage. Also, activity of antioxidant enzymes such as superoxide dismutase (1.7-fold), catalase (2.57-fold) and peroxidase (5.5-fold) were found to be significantly increased in D stage. Sucrose concentration (4.7-fold) also increased during desiccation. The quantity of starch (0.5-fold) was lower in the D stage. In R stage, all biochemical parameters tested above were significantly similar to that in the H stage. S. repanda exhibits constitutive and inducible repair mechanism towards desiccation and can therefore serve as model to study desiccation in Selaginella species.