Ascorbic Acid: Potential Antioxidant Counteracts Leaf Senescence by Alleviating Oxidative Stress in Bergenia ciliata (Haw.) Sternb

The major goal of this study was to determine the efficacy of exogenous ascorbic acid (AsA) in reducing oxidative stress in leaf discs of Bergenia ciliata during two phases of leaf growth (S1; 30 days after opening of the leaf bud and S2; 60 days after opening of the leaf bud) with the ultimate aim of delaying leaf senescence. The leaf discs obtained from harvested leaves were supplemented with various concentrations of AsA (after standardization) viz., 5, 10, 15 and 20 (µM) in borosilicate petriplates. The control group consisted of a set of leaf discs preserved in distilled water. When compared to control, AsA was found to be effective in improving the life span of leaf discs as noticed from an enhancement in the concentration of chlorophyll a and b, augmented antioxidant activity of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), abridged lipid peroxidation (LPO) with a proportional increase in membrane stability index (MSI) and enhanced phenolic contents. The discs with delayed senescence also displayed higher sugar contents, enhanced soluble proteins. The fresh and dry mass of leaf discs supplemented with different concentrations of AsA was also higher when compared to control. Moreover, the leaf discs treated with AsA exhibited a decline in the activity of lipoxygenase (LOX) and 20 µM concentration of AsA also inhibited the discoloration of solution in the petriplates.