Water deficiency-induced changes in the contents of defensive substances against active oxygen in spinach leaves.

Abstract

Changesin the contents of defensive substances against the active oxygenin water-stressed spinach plants were examined. The contents of ascorbate peroxidase (AP; EC 1.ll.1.7), glutathione reductase (GR; EC 1.6.4.2) and a-tocopherol increased remarkably in water-stressed spinach leaves, while those of superoxide dismutase (SOD; EC 1.15.1.1), dehydroascorbate reductase (EC 1.8.5.1), ascorbate and glutathione changed little. The content of a-tocopherol in chloroplast thylakoid membranesisolated from water-stressed leaves was higher than that from normal leaves. It is, therefore, conceivable that GR, AP and a-tocopherol might be related to the tolerance of plants to water deficiency.