The relevance of seed membrane lipids to imbibitional chilling effects

Imbibitional chilling injury during rehydration of seeds is particularly marked in soybean but not in pea. Following the previous reports that the deleterious effects of chilling on soybean germination are probably mediated at least in part through a loss of membrane integrity, differences in composition of membrane lipid components extracted from pea (chilling-insensitive) and soybean (chilling-sensitive) were examined. Comparative compositional analysis of phospholipids, fatty acids and free sterols revealed few disparities between the two species. When the membrane lipids were re-formed into liposomes, little difference in permeability was found with respect to KCl, glucose or glycerol, even at chilling temperatures. It is suggested that the difference in chilling sensitivity between pea and soybean is not related to compositional differences in the major lipid components of the seed membranes.