Trichoderma and spermidine improve cadmium tolerance and phytoremediation potential in purslane (Portulaca oleracea L.) plant

To better understanding, the physiological and biochemical mechanisms of Trichoderma longibrachiatum (TL) and spermidine (SPD) polyamine treatment on cadmium (Cd) tolerance phytoremediation in purslane (Portulaca oleracea) plant and the activity of anti-oxidants enzyme (CAT, APX, POX, SOD), hydrogen peroxide and proline content as well as determination cadmium accumulation in shoots, roots, soil and their ratio to each other, a factorial experiment was performed in a completely randomized design with three replications and three treatments. In the current study, mitigative roles of SPD and TL were assessed in Cd stressed Portulaca oleracea plants. SPD (1, 0.5, and 1 mM) was applied after 20 days of sowing on the branches and leaves of plants inoculated or without TL inoculating in the presence of Cd (0, 30, 60 and 90 mg.kg-1). Cd stress and coexistence with TL increased the activity of antioxidant enzymes and leaf soluble protein in purslane plants. Also, the application of SPD, especially at 0.5 mM, resulted in a higher increase in leaf protein under cadmium stress in inoculated plants. Proline parameter responds differently to TL. SPD application reduced the severity of these changes. The amount of H2O2 was significantly reduced in plants when treated by both TL and SPD. Significant differences were observed between 0.5 and 1 mM of SPD in terms of the Cd uptake in the TL inoculated purslane shoots. Inoculated purslane plants treated by either 0.5 or 1 mM of SPD had lower Cd uptake and greater BF. In general, the results showed a synergetic effect between TL fungi and SPD application on improving the Cd phytoremediation in the purslane plant.