离体条件下耐重金属镉暗隔内生真菌筛选及耐毒性机制的初步研究OA

To explore the tolerance of dark septate endophytes(DSE)in the roots of Pinus sylvestris var.mongolica to heavy metal Cd,we selected a strain with the strongest resistance by plate and liq-uid fermentation culture method,determined its physiological index of resistance under different con-centrations of Cd stress,and observed the morphological changes of mycelia by scanning electron mi-croscopy to further study tolerance mechanisms.The results show that the growth rate and biomass of the highly resistant strain A041(paraphoma chrysanthemicola)were significantly higher than those of other strains under different concentrations of Cd stress.The main resistance physiological indicators of A041 were significantly improved and different from the control(P<0.05),and with the increase of Cd concentration,the activities of catalase(CAT),peroxidase(POD)and superoxide dismutase(SOD)reached the maximum at Cd concentrations of 3 mmol/L,5 mmol/L,and 6 mmol/L,respectively,which were 215%,92%and 122%higher than those of the control group.The contents of malondial-dehyde(MDA)and soluble protein were the highest at Cd concentration of 7 mmol/L,with increases of 193%and 47%,respectively,compared with the control.Glutathione(GSH)content increased first and then decreased,reaching a peak at Cd concentration of 2 mmol/L,with an increase of 42%com-pared with the control;melanin content in A041 mycelium showed a trend of increasing first and then decreasing with the increase of Cd stress,with the highest content at Cd concentration of 2 mmol/L,with an increase of 34%compared with the control.Different concentrations of Cd stress could change the mycelial morphology of strain A041.As Cd concentration increased,the mycelial diam-eter decreased and mycelia became increasingly sparse.It is concluded that strain A041(P.chrysan-themicola)has a strong Cd tolerance.