| Copper and Zinc are not only essential nutrition elements for plant growth and development, but also poisonous heavy metal elements. In the present study, the aseptic seedlings of Potamogeton crispus L. were selected as the experimental material and the Cu, Zn2+were used as the stress factor. The changes of physiological characteristics in the aseptic seedlings of P. crispus were investigated by applying technology of plant physiology and biochemistry. The results are as follow:(1)Steriled seedlings of Potamogeton crispus L when exposed to various concentrations of Cu2+(0-11μM) for 1-5 days, exhibited both phytotoxic and tolerance response. The specific responses were function of concentration and duration. The toxic effect and oxidative stress caused by Cu2+ were evident by the reduction in photo synthetic pigments and increase in malondialddehyde (MDA) content, soluble protein and proline increased at first and then decreased and Ca2+-ATPase activity, Na+/K+-ATPase activity with decrease rapidly in metal concentration and exposure duration. The metal tolerance and detoxification strategy adopted by the plant was investigated with reference to antioxidant system. antioxidant enzymes viz., superoxide dismutase(SOD) activity increased gradually; while Activities of peroxides (POD) and catalase (CAT), as well as contents of reduced glutathione (GSH), ascorbate (AsA), non-protein thiols (NP-SH) increased at first and then decreased. Our results demonstrated that Cu2+induced the enhancement of reactive oxygen species level, aggravated lipid peroxidation and interfere with intrinsic balance of antioxidant defense system. Plants through enhanced level of various antioxidants on the oxidative stress could play a significant role in the adaptation mechanism of sterile seedlings of P. crispus under Cu2+ stress.(2)In order to study the toxic effect of Zn2+ in sterilized seedlings of Potamogeton crispus L, in this paper, the effects of different concentrations of Zn2+(0-0.4mmol/L) on the content of chlorophyll content, (MDA) content and hydrogen peroxide (H2O2) content, generation of superoxide anion (O2-), Ca2+-ATPase and Na+/K+-ATPase activity were investigated and the differences of infrared spectral of the chemical composition were analyzed. The toxic effect and oxidative stress caused by Zn2+were evident by the reduction in photo-synthetic pigments and increase in malondialddehyde (MDA) content, the production of excess O2+ and H2O2 and Ca2+-ATPase activity, Na+/K+-ATPase activity with decrease rapidly in metal concentration and exposure duration; the absorption peak shapes of the various parts the Potamogeton crispus L have not great change, but the absorbance havw obvious changes, indicating that the Zn2+ concentration does not change the material composition, but change the content. In addition, Zn2+ stress disturbed the function of Ca2+-ATPase and Na+/K+-ATPase, disordered the absorption, transport and metabolism of mineral nutrient, which all caused damage to cells.(3)To study antioxidant intervention compensates oxidative stress in sterilized seedlings of Potamogeton crispus L. exposed to Zn2+ stress for 5 days, the effects of increasing Zn2+ concentration on the antioxidant system, the content of VE, total flavonoids, soluble protein, proline and mineral nutrient content were investigated. The metal tolerance and detoxify-cation strategy adopted by the plant was investigated with reference to antioxidant system, antioxidant enzymes viz., superoxide dismutase(SOD) activity increased gradually; while Activities of peroxides (POD) and catalase (CAT), as well as contents of reduced glutathione (GSH), proline, and total antioxidant capacity (T-AOC) increased at first and then decreased, but the contents of the content of VE, total flavonoids, soluble protein were found to increase in a concentration-dependent manner. Analysis of nutrient elements showed that the levels of total Na、K、P、Mg、Cu fell and the level of total Ca increased initially only to decline later. The up-regulation of antioxidant enzymes activities and the content of antioxidant material of P. crispus resist Zn2+stress reduced the toxic effects to some extent, but along with the increasing concentrations of Zn2+ stress, the balance of antioxidant system was destroyed, eventually resulting in nutrients absorption and metabolic disorders. |
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