Water Stress and —SH-Dependent Physiological Activities in Young Maize Plants

Abstract

In young maize plants, water stress affects the —SH-dependent activities: photosynthesis and dark respiration are reduced to about 60% at the wilting point; protein synthesis is inhibited even by moderate stress; and nitrate reductase activity is immediately inhibited also, prior to significant changes in the water status of the plant. As protoplasmatic protein denaturation occurs, protein —SS— increases at the expense of —SH, with consequent decrease of the —SH/—SS— ratio. The linear correlation between — SH/—SS— ratio and —SH-dependent activities suggests a strict depen dence between them. A moderate increment both in rhodanese activity and labile sulphide content has been also demonstrated at the beginning of the stress.