Although the cold hardiness of primary buds has been examined for grape cultivars and is used as a principle factor of grapevine cold hardiness, freezing tolerance capacity in the rest of the vine has received relatively little attention. This investigation characterized freezing tolerance and protein expression of `Frontenac' and `Seyval blanc' grape cane tissues during the overwintering periods of autumnal cold acclimation, midwinter, and vernal deacclimation including dehydrin proteins that may be used to describe cultivar freezing tolerance. Controlled, laboratory freezing tests were conducted with field acclimated or deacclimated bark and xylem tissues from grape canes. SDS-PAGE profiles and immunoblots for dehydrins were used to qualitatively and quantitatively assess protein expression. `Frontenac' bark tissues demonstrated a capacity to achieve greater freezing tolerance than xylem tissue in late acclimation and midwinter, which may have contributed to greater overall freezing tolerance during midwinter. On the other hand, `Seyval blanc' showed a greater capacity for reacclimation after a freezing event during the observed

deacclimation period. SDS-PAGE profiles showed a 36-kDa protein expressed during the lowest air temperatures and when the lowest LT_{50 values for `Frontenac' tissues were observed, both occurring during the midwinter period. SDS-PAGE profiles showed a 36-kDa protein expressed during the lowest air temperatures and when the lowest LT50 values for `Frontenac' tissues were observed. Although the 36-kDa protein was not identified as a dehydrin, proteins at 43, 41, 39, 19, 12 and 10 kDa were confirmed as dehydrins. Tissues that were observed to have the greatest capacity for midwinter freezing tolerance also showed greatest expression of a 39-kDa dehydrin. The 12 and 10-kDa dehydrins were not visible on SDS-PAGE profiles, but were detected by the antidehydrin antibody. A 12-kDa dehydrin appeared unique to `Frontenac' and a 10-kDa dehydrin was unique to bark profiles. The 36-kDa protein and dehydrins at 39, 12, and 10 kDa had greatest association with high freezing tolerance in grapevine.}