Toxicological Effects Of Manganese Stress On Purple Duckweed And Potamogeton Crispus

In the present study, we chosed Spirodela polyrhiza and Potamogeton crispus as the experimental materials, Mn2+ as intimidation factor. Under the experimental conditions, plant tissue culture technology, claser scanning confocal microscope (CLSM), fourier transform infrared spectroscopy (FTER), high performance liquid chromatography (HPLC) and so on were used to study the stress effects of heavy metal manganese in S. polyrrhiza, aseptic and field seedlings of P. crispus. The results were as follow:(1) With different concentrations of Mn2+ (0,10,20,30,40,50 μmol/L) cultured for 2 weeks, fourier transform infrared spectroscopy (FTIR), flavonoids, reactive oxygen species, malondialdehyde (MDA), antioxidant system, photosynthetic pigment, the content of soluble protein and the total antioxidant capacity. The results showed that S. polyrrhiza exhibited a series of physiological and biochemical changes under the stress of manganese. The total flavonoids content was first increased and then decreased. S. polyrrhiza accumulated a large number of reactive oxygen species (production rate of superoxide anion to accelerate and the content of hydrogen peroxide to increase) and membrane lipid peroxidation was enhanced (the content of MDA to increase). Photosynthetic pigments were destroyed while soluble protein content was reduced. Antioxidant system of S. polyrrhiza was also affected by the interference of Mn2+, for the content of vitamin C (Vc) and vitamin E (Ve) decreased constantly and glutathione (GSH) changed unconspicuously. Meanwhile non protein thiols (NP-SH) increased firstly and then decreased. The activity of catalase (CAT) decreased but the activity of superoxide dismutase enzyme (SOD) and peroxidase (POD) increased. And the total antioxidant capacity increased first and then decreased. These and changes of materials (carbohydrates, component of cell walls and membranes, proteins, carboxylic acids, phenols, etc.) that characteristic peaks of fourier transform infrared spectroscopy (FTIR) were on behalf of, showed that high concentration of manganese caused serious damage in S. polyrrhiza.(2) The effects on the field and aseptic seedlings of P. crispus were studied under the treatment of different concentrations (0,0.1,0.2,0.4,0.8 mmol/L) of MnCl2 for one week. We investigated the fourier transform infrared spectroscopy (field seedlings of P. crispus), chloroplast autofluorescence (field seedlings), the content of amino acid hydrolysis (aseptic seedlings), activity oxygen, the content of malondialdehyde (MDA), antioxidant system, photosynthetic pigment, the content of soluble protein and the total antioxidative capacity. The research results showed that the effects of Mn2+ in P. crispus were various. Characteristic peaks of fourier transform infrared spectroscopy (FTIR) on behalf of the materials (carbohydrates, component of cell walls and membranes, proteins, carboxylic acids, phenols, etc.) changed differently. Chloroplast autofluorescence was abate, while the content of chlorophyll and carotenoid decreased. In addition, the content of hydrolytic amino acid, soluble protein, vitamin C (Vc) and vitamin E (Ve) were increased in low concentrations but reduced at high levels of stress. A large number of reactive oxygen species was accumulated (production rate of superoxide anion to accelerate and the content of hydrogen peroxide to increase) and membrane lipid peroxidation was enhanced (the content of MDA to increase). The activity of superoxide dismutase (SOD) enhanced which played the main antioxidant effect,whereas the activity of catalase (CAT) and T-AOC both rised then reduced. In the experimental period, high concentrations of manganese processing had obvious toxic effects on P. crispus.