Relief Effects Of Ascorbic Acid To The Damage Of High Aquatic Plants Under The Stress Of Heavy Metals

The relief effects of the ascorbic acid to the damage of aquatic plants Hydrilla verticillat Linn and Potamogeton crispus Linn. produced by heavy metal Cd²⁺ and Hg²⁺ were measured by physiological and biochemical indexes, observation of electron microscopy and SDS-PAGE. The results showed obvious damage to the photosynthetic systems, protective enzyme systems (including SOD, POD, CAT and APX), antioxidant substance (AsA and GSH) content, substance metabolism systems, protein synthesis and cell ultrastructure of the plant by the heavy metal ion of cadmium and mercury. Resistance ability from endogenous protective enzyme systems and antioxidant substance content in the plants was enhanced by the inducement of heavy metal stress in restricted range but they were diminished by exorbitant concentration of heavy metal ion. The optimum concentration exogenous ascorbic acid can reduce concentration of Cd²⁺ and Hg²⁺ in cell, weaken the damage of Cd²⁺ and Hg²⁺ to the chlorophyll, improve or reduce the activities of antioxidant enzyme, depress the levels of reactive oxygen species (O₂^-.,H₂O₂ and·OH ), slack the oxidation of reactive oxygen species to the membrane and the damage of Cd²⁺ and Hg²⁺ to cell ultrastructure of the plant. But the relief effects of ascorbic acid to the damage of high aquatic plants under the stress of heavy metals is related to its concentration and exorbitant concentration of ascorbic acid acts on the plant cooperated with heavy metal. The damage of heavy metal and the relief of ascorbic acid are related with the time they had done. Several special protein bands in SDS-PAGE will dissolve affected by certain concentration heavy metal after ten days.