Ascorbic Acid Protects Soybean Plants Against Ni- Induced Oxidative Stress
2006
Saeidi-Sar, S., Science and Research Branch, Islamic Azad University, Tehran, Iran. | Khavari-Nejad, R.A., Science and Research Branch, Islamic Azad Uneversity, Tehran, Iran; Department of Biology, University of Tehran, Iran; | Fahimi, H., Science and Research Branch, Islamic Azad University, Tehran, Iran. | Ghorbanli, M., Gorgan Branch, Islamic Azad Uneversity, Gorgan, Iran. | Majd, A., Science and Research Branch, Islamic Azad University, Tehran, Iran; Department of Biology, University of Teachers Education, Tehran, Iran.
In the present research, we studied the effects of ascorbic acid (AsA) to act as a highly effective antioxidant in soybean (Glycine max L. cv. Union × Elf) plants undergoing oxidantive stress caused by nickel (Ni). One-week-old hydroponically-grown seedlings were exposed to variable concentrations of NiCl2, 6H2O (0, 0.5,1mM) and AsA(0,1mM). Ni was more accumulated in roots than in shoots. Surprisingly, root-to-shoot translocation of Ni depressed by ASA. In the absence of ASA, excess Ni suppressed biomass production of both roots and shoots and reduced chlorophyll content in leaves, while ASA removed these effects. The existence of Ni induced oxidative stress can be demonstrated by an increasing in malondialdehyde (MDA) production. This rise could be explained by activation of the enzyme lipoxygenase (LOX, EC.1.13.11.12). Addition of ASA together with Ni ions, almost completely restored LOX activity and reduced MDA production. In the other hand, ascorbate peroxidase (APX, EC 1.11.1.11) and catalase (CAT, EC 1.11.1.6) activities in both roots and leaves were strongly reduced by Ni stress. While ASA highly increased APX and CAT activities in Ni-stressed plants.Consequently, ascorbic acid by sequestration of Ni in roots and with an altogether increases in the activities of antioxidant enzymes reduces Ni induced oxidative damage in a certain extent.
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