Lipid Peroxidation in Cadmium-Treated Phaseolus coccineus Plants

Abstract

Lipid peroxidation was examined in Phaseolus coccineus plants treated with 25 microM Cadmium (Cd) for 12 days at two different growth stages of the primary leaves. In the leaves of Cd-treated young plants, the content of free fatty acids was higher only after 8 days of plant exposure to the metal, lipoxygenase activity at pH 7.0 was enhanced after 6 and 8 days of Cd action, but at pH 8.0 it was higher than control, especially after 8 days. Non-enzymatic lipid peroxidation was higher after 6 days of young plant exposure to the metal, but after 8 days it slightly decreased. Glutathione-S-transferase activity decreased during 12 days of the metal action but it was always higher than in control. Anthocyanin content in these plants was also elevated in comparison with control. In Cd-treated older plants, the level of free fatty acids was always higher as compared to control. Lipoxygenase activity at pH 7.0 was lower after 4 days of plant exposure to the metal, but then it was close to control. The enzyme activity at pH 8.0 and the level of lipid peroxidation were lower during 12 days of Cd action in comparison with control. Glutathione-S-transferase activity and anthocyanin pigment content were higher in older Cd-treated plants than in control. Relationships between the pool of free fatty acids, a low level of lipid peroxidation, and glutathione-S-transferase activity in the primary leaves of Cd-treated Phaseolus coccineus plants are discussed. In these plants, lipid peroxidation is under the strict control of metabolism and the antioxidative system works efficiently.