Simultaneous comparisons were made between a freezing-tolerant, cold-acclimating (CA) wild potato species (Solanum commersonii) and a freezing-sensitive, nonacclimating (NA) cultivated species (Solanum tuberosum). Comparative studies allowed differentiation of plasma membrane lipid changes associated with increased freezing tolerance following CA from lipid changes that can result from metabolic adjustment to reduced temperature during CA. Following CA treatment lipid changes found in both the NA and CA species included a decrease in palmitic acid, an increase in unsaturated to saturated fatty acid ratio, an increase in free sterols, an increase in sitosterol, and a slight decrease in cerebrosides. Lipid changes detected only in the acclimating species included an increase in phosphatidylethanolamine, a decrease in sterol to phospholipid ratio, an increase in linoleic acid, a decrease in linolenic acid, and an increase in acylated steryl glycoside to steryl glycoside ratio. These changes were either absent or opposite in the NA species, suggesting an association of these lipid changes with CA. Furthermore, the lipid changes associated with increased freezing tolerance during CA were distinct from lipid differences between the two species in the NA state.

ABSTRACTtions suggests that both traits are controlled by relatively few genes. To our knowledge this is the first study demonstrating independent genetic control of the two main traits associated with frost or winter survival. Our results show that it should be possible to incorporate these traits from wild germ plasm into cultivated crop plants by independent selection. These results help explain the lack of progress in improving winter survival through field selection. Furthermore, our study demonstrates relative simplicity of the inheritance of cold acclimation, thus providing avenues for understanding the link between biochemical and genetic aspects of low-temperature stress in crop plants.

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