Alteration of Protein Composition of Corn (Zea mays L.) Seedlings During Moisture Stress1

Abstract

The rapidity and magnitude of change in nitrate reduction and assimilation, protein metabolism, and associated ribonucleic acid were investigated in corn (Zea mays L.) seedlings subjected to moisture stress. The objective of the study was to determine the sequence of events that lead to protein alteration. Nitrate reductase was highly susceptible to tissue dehydration and markedly lost activity with only slight reductions in leaf relative turgidity. Reduced protein synthesis instead of increased protease activity caused leaf protein concentration to decrease during severe moisture stress conditions. Appreciable loss of protein was not detected during mild stress. Alterations in RNA synthesis appeared to be as important as increased RNase activity in determining leaf RNA concentration during mild stress. During severe stress, however, increased RNase activity was probably more important in decreasing RNA.