ABSTRACT
The amount and distribution of tissue water is an important factor in freeze survival of plants. Genetically competent plants tolerate extracellular ice when adequately cold acclimated, but succumb to intracellular ice formation. D. G. Stout described the physical/chemical effects of extracellular ice on cell dehydration among freeze-resistant and -susceptible winter wheat cultivars. Proteins of the intercellular fluid have been investigated in pathogenesis. Protein content in the molecular sieved extracellular fluid (ECF) from freeze-resistant (FR) and freeze-susceptible (FS) leaf tissue. The larger amounts of extracellular protein found in the FR cultivar compared to FS cultivar suggest greater export to the cell surface. Lower tissue water increased ECF protein and, to a larger extent, increased ECF protein in the FR cultivar. Differences in protein amounts of the ECF between the cultivars or changes resulting from reduced tissue water content reflect a nonspecific influence on macromolecular export.
