Water stress and SH dependent physiological activities in young maize plants.

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 dependence between them. A moderate increment both in rhodanese activity and labile sulphide content has been also demonstrated at the beginning of the stress.