The Activity and Gene Expression of Enzymes in Mycelia of Pleurotus Eryngii under Cadmium Stress

Cadmium (Cd) is a highly toxic pollutant and a nonessential element for plant growth. Here, we investigated the levels of malondialdehyde (MDA), H2O2, sugars, and the activity and gene expression of antioxidant enzymes and sugar metabolism-related enzymes in the mycelia of Pleurotus eryngii grown in the presence of 0, 0.5, 1, 1.5, 2.0, and 4.0 mg center dot L-1 Cd. Raising Cd concentration resulted in increases, followed by decreases in the levels of malondialdehyde (MDA) and H2O2 in the mycelia. The maximum concentrations of MDA and H2O2 reached 318.61 and 7411.40 mu mol center dot L-1, respectively, at a Cd concentration of 1 mg center dot L-.(-1) Antioxidative enzymes (superoxide dismutase (SOD), catalase, glutathione peroxidase (GPX), and ascorbate peroxidase (APX)) activities peaked at 1 mg center dot L-1 Cd. Furthermore, Pleurotus eryngii produced trehalose, glucose, fructose, and maltose in the fermentation broth in response to Cd stress. The levels of trehalose, arabinose, and fructose in the fermentation broth decreased continuously. The levels of glucose increased continuously, whereas those of maltose first increased and then decreased. Gene expression level of chitin synthase, glucose-1-phosphate uridyl transferase peaked significantly at 2 mg center dot L-1 of Cd, while that of trehalase 2 is 0.5 mg center dot L-1, and those for fructose-diphosphate aldolase, glyceraldehyde-3-phosphate dehydrogenase, reached the maximum at 4 mg center dot L-1.