Cadmium Accumulation in <i>Marsilea minuta</i>Linn. and Its Antioxidative Responses

The present study was carried out to investigate the extent of cadmium (Cd) accumulation with its possible impact on physiological and biochemical basis of heavy metal tolerance in Marsilea minuta Linn. Cd salt (0 μM, 50 μM and 100 μM) was allowed to absorb by the plants for prolong days in hydroponic culture and a significant deterioration of the plant biomass was recorded. However, roots absorbed more metals than the leaves. Plants recorded a significant rise of superoxide (O-2) and hydrogen peroxide (H2O2). A noticeable amount of protein oxidation and lipid peroxidation were in proportionate to Cd accumulation. Anthocyanin and flavonoid content were decreased as compared to control condition. Superoxide dismutase (SOD), guaiacol peroxidase (GPX) and glutathione reductase (GR) contributed their antioxidative functions according to the Cd doses. The expression of GR was also evident from its activity staining in gel. So, it may suggest that antioxidative enzymes are up regulated and likely to be responsible for tolerance to Cd induced oxidative stress in Marsilea minuta Linn.

Responses of <i>Marsilea minuta</i>L. to Cadmium Stress and Assessment of Some Oxidative Biomarkers

In a hydroponic based experiment, the Cd toxicity is monitored with some cellular responses of Marsilea plant. Initially, plants were grown under varying concentrations (0, 50, 100 and 200 μM of Cd) of cadmium (Cd) with supplementation of 2 mM spermidine (Spd). The oxidative stress developed by Cd overaccumulation was measured with fall in Relative Growth Rate (RGR) by 27.11% to 59.83% growth reduction over control under varying Cd treatments. The retrieval of RGR was recovered by 1.59 folds as compared to the highest concentration of Cd (200 μM) when plants were fed with Spd. A concomitant degradation of chlorophyll was recorded in dose-dependant manner, however, the retrieval was not much pronounced with Spd. On the contrary, the non-oxidant thiol had borne more clarity with ongoing Cd concentration and appeared to be 40.51% increase maximally for GSH: GSSG at the highest concentration of Cd. Spd has minimized the ratio by 27.4%. The recovery of osmotic turgidity was indexed with a sharp rise in glycine betaine by 3.86 folds maximum at the highest concentration of Cd over control which declined by 30.9% with Spd. Another cellular response of treated plants was more evident from their isozymic profiles with regard to superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX). The intensity of protein expression was significantly variable but not in band numbers as evident from Cd treated plants. In vitro enzyme assay of catalase showed as declining trend within the limit of 33.13% to 43.22% which was reported by 1.45 folds when Spd was applied. Therefore, from the present study, the cellular responses of Marsilea plant which showed compatibility for their expression with Cd toxicity could be hypothesized as a case of bioindication.