The pattern of proteins and of peptide hydrolase activities in shoots of field-grown winter wheat during the cold season

Abstract

Winter cereals in the field are subject to low temperatures during an early stage of vegetative growth. Metabolic activities are low during this period. The quantities of enzymes involved in nitrogen assimilation, carbon assimilation and photorespiration were analyzed by gel electrophoresis and immunoblotting. The levels of all enzymes studied were well maintained throughout the winter, even during 2 marked low-temperature phases. The activities of various peptide hydrolases were measured in the same samples. The major endopeptidase activity at pH 5.0 remained relatively constant during the winter, while aminopeptidase and carboxypeptidase activities increased during a warmer phase at the beginning of January. The maintenance of important assimilatory enzymes during the period of low metabolic activity may allow a rapid restart of growth in spring.