Expression of heat shock proteins in dormant buds of grape (Vitis vinifera L.)

Dormant grape (Vitis vinifera L.) cuttings were removed from cold storage (3 degrees C) and incubated at 25 degrees C or 45 degrees C for 30 minutes (heat shock treatment), followed by four hours at 25 degrees C, Control cuttings were held at 3 degrees C. Bud proteins were separated by two-dimensional electrophoresis. Thirty-two proteins accumulated following heat shock at 25 degrees C, and 112 accumulated following heat shock at 45 degrees C. Relative to the control, 10 proteins decreased in the 25 degrees C heat shocked buds, but were present at similar or greater concentrations in the 45 degrees C heat shocked buds. Two-dimensional western immunoblots revealed three HSP70 isoforms (pIs 5.84, 5.86, and 5.90) in the control buds, and much larger amounts of two of the isoforms (pIs 5.86, and 5.90) in the 45 degrees C heat shocked buds. The 25 degrees C heat shocked buds had a small amount of only one HSP70 isoform (pI 5.90). The decrease in HSP70 following heat shock at 25 degrees C raises the possibility that changes in the protein profile at this temperature may not be related to a heat shock response, even though 25 degrees C for 4.5 hours has been shown to confer increased thermotolerance. Heat shock at 45 degrees C, which confers greater thermotolerance, is correlated with increased expression of HSP70 as well as other proteins.