CADMIUM AND NICKEL COMBINED EFFECT ON ASCORBATE-DEPENDENT MECHANISM OF ANTIOXIDATIVE DEFENSE SYSTEM OF PEA

• Main Authors: T. A. Artiushenko, V. M. Gryshko
• Format: Article
• Language: English
• Published: Bogdan Chmelnitskiy Melitopol State Pedagogical University 2014-04-01
• Series: Bìologìčnij Vìsnik Melìtopolʹsʹkogo Deržavnogo Pedagogìčnogo Universitetu Imenì Bogdana Hmelʹnicʹkogo
• Online Access: http://ojs.mdpu.org.ua/index.php/biol/article/view/816

The dynamics of changes in the content of different forms of ascorbic acid and ascorbate peroxidase activity in pea vegetative organs as components of antioxidant protection for the cadmium and nickel combined effect is investigated. It was established, that in assimilation tissues of pea the seedlings amount of ascorbic acid reduced form was more higher compared to the roots by 9 times. Using of toxicants in high concentration in the first hour of exposure, probably resulted a significant activation of the ascorbic acid synthesis in pea roots, as indicated by the increase in its quantity by 44%. In the early stages of ontogeny with increasing duration of cadmium and nickel compounds stress action to 7 hours in pea roots showed a trend towards increase in ascorbic acid at 23-68% in all the variants of the experiments. The aforementioned was accompanied by significant increase of the level of dehydroascorbate acid and product of ascorbate irreversible oxidation – 2,3-diketogulonic acid. By contrast in the leaves under the toxicants influence at low concentrations is not the case of ascorbate amount changes. However we registered the increasing of dehydroascorbate acid amount by almost 20% compared to control, which may indicate the induction of the antioxidant synthesis. In other cases, there was a tendency to decrease in the ascorbic acid content. The study content of ascorbic acid various metabolites in the pea roots to 12 hours stressful action of cadmium and nickel compounds showed violations in pro-/antioxidant balance. This was confirmed by a decrease content of reduced ascorbate regards control level. After a 12-hour of stress the ascorbate amount decreased, whereas dehydroascorbate and 2,3-diketogulonic acids continued to increase. Existing experimental data allows conclude that the 12 hour exposure of pea plants in a medium with a low concentration of the cadmium and nickel compounds the ascorbic acid content in the leaves increased towards control level, i.e. there is a significant induction of the synthesis process. In addition, the amount of ascorbate oxidized forms, as in previous research period, continued to increase. After 24 hours of experiment we registered similar to 12 hours trend of changes in the content of ascorbic acid metabolites. Violation of pro-/antioxidant balance also accompanied by increased ascorbate peroxidase activity. In the pea root system there is the tendency to increase the ascorbate peroxidase activity and this is in concordance with the increasing content of ascorbic and dehydroascorbate acids. At the beginning of stressful activities caused by cadmium and nickel compounds in the leaves is not the case of ascorbate peroxidase activity changes, although 7-hour influence resulted in a statistically significant increase in activity specified oxidoreductase. By the action of heavy metals in low concentrations the content of ascorbic acid in pea leaves increased by 14%. High content in the medium of at least one of the metals since 7-hour exposure caused the depletion of antioxidant resources, as evidenced by the decrease of ascorbic acid in the assimilation organs. After 24 hours of experiment we observed a slowdown in ascorbate peroxidase activity, which could be explained by the lack of ascorbic acid under prolonged stress exposure. Keywords: Pisum sativum L., cadmium, nickel, ascorbic acid, ascorbate peroxidase.