Activity and localization of lipoxygenase in the ovule of Larix kaempferi (Lamb.) Carr. during megasporogenesis
The activity of lipoxygenase (EC 126.96.36.199) in Arabidopsis thaliana (L.) Heynh seedlings and mature plants was estimated spectrophotometrically at 234 nm. Linoleic acid was used as a substrate. Lipoxygenase activity showed two pH optima: at 7.0 and 10.0 in seedlings, and at pH 8.0 and 10.0 in leaves of mature plants. Seven-week-old plants were transferred to a hydroponic system and treated with different concentrations of Cd(2+) or Cu(2+) [in microM]: 0, 5, 25, 50, 100 for 7 days. The lipoxygenase activities at pH 8.0 and 10.0 depended on the metal that was added to the nutrient solution. The main change in lipoxygenase activity was under Cd(2+)stress at pH 8.0 and under Cu(2+)excess at pH 10.0.