Technical Abstract: Experiments were conducted to identify and characterize protein changes specifically associated with either cold acclimation or dormancy in temperate fruit crops. This was accomplished by using, in the first experiment, sibling deciduous and evergreen peach genotypes to study seasonal pattern of cold hardiness and protein changes in bark tissues. In nthe second study, differential expression of previously identified 65- and 60-kD dehydrin proteins and their association with cold acclimation or endodormancy in blueberry buds was evaluated. Cold hardiness or dormancy status of blueberry buds was differentially modified by manipulating temperature treatments. Protein profiles and their immunoblots were then compared with changes in cold hardiness and dormancy. Results from these studies indicate: 1) A 60-kD peach-bark protein is closely associated with cold hardiness rather than endodormancy. 2) The 60-kD protein is a dehydrin protein. 3) The blueberry cultivar 'Tifblue' exhibited cold acclimation during a four degree C treatment (for three weeks) which also satisfied one-half of its chilling requirement. This was paralleled by an accumulation of 65- and 60-kD dehydrin-like proteins. 4) Levels of these proteins declined following a two-week exposure of buds to 15/12 degree C (D/N) (a treatment that resulted in deacclimation but did not negate chill unit accumulation). These results suggest that a 60-kD dehydrin protein in peach and 65- and 60-kD dehydrin proteins in blueberry buds is associated with cold acclimation but not with dormancy.