Augmentation of protoplasm in drought- and cold-hardened winter wheat

Abstract

A 24-h desiccation stress at 40% relative humidity was able to induce the same degree of freezing tolerance as a 4-week cold acclimation at 2 °C does in nine cultivars of winter wheat. These two treatments were also able to elicit similar metabolic changes as indicated by increases of soluble protein and phospholipid contents in shoots. Since the amplitude of these metabolic changes induced by drought and cold stresses were similar, the mechanism or the mechanisms by which these stresses induce freezing tolerance appear to involve the same biochemical modifications.The measured amplitude of these metabolic changes is not always proportional to the net increase of freezing tolerance among those cultivars but depends upon the method used to determine the metabolites. A strong correlation between the amplitude of the increase of soluble proteins and phospholipids and the net increase of freezing tolerance of the cultivars was observed only when the extractions were performed on lyophilized tissues.