Effects of Exogenous Spermidine on Cell Wall Composition and Carbohydrate Metabolism of Marsilea Plants under Cadmium Stress

In an experiment to detect the cellular changes of carbohydrate content and its related enzymatic activities, a study was undertaken with Marsilea minuta L., an aquatic fern species in simulated condition of cadmium (Cd) toxicity. From the varying doses of Cd (0, 50, 100 and 200 μM) and supplemented with spermidine (2 mM), it revealed that plants were suffered from accumulation of total carbohydrate in a dose-dependent manner under Cd stress. Maximum depletion of carbohydrate content was 58% with respect to control which was retrieved by 1.42 fold with spermidine application. In a similar manner, plants were also affected with starch, total reducing sugar content by 42% and 63.04% respectively over the control. The fall in both starch and total reducing sugar were retrieved by plants by 1.32 fold and 1.52 fold, respectively. On the contrary, plants were up regulated in structural carbohydrates in the forms of cellulose and hemicelluloses by 3.84 fold and 4.66 fold. On account of enzymatic activities, plants recorded a significant down regulation of soluble invertase and wall-bound invertase activities by 51.27% and 42.07% maximally over control and thus proved their fair integrity with carbohydrate metabolism. Spd, regardless of those enzymes, could regain the activity by 1.66 fold and 1.53 fold. Cd toxicity has raised some sort of anaerobic stress thereby Marsilea plant have tended to exercise alcohol dehydrogenase (ADH) and malate dehydrogenase (MDH) enzyme, the two anaerobic stress-induced proteins by 1.83 fold increase and 58.34% decline maximally through course of Cd concentration. It is interesting to note that α and β amylase activity set another cellular trait which has undergone varied depletion with the value of 50.42% and 44.53%, respectively through Cd concentration over control. Spd though retrieved the activities for both of those but not statistically significant. Therefore, Marsilea plant had defolded its cellular responses in diverse aspect of carbohydrate metabolism and those could be illustrated as biomarkers for Cd in aquaic environment.