Expression of Heat Shock Proteins in Dormant Buds of Grape (Vitis vinifera L.)

Abstract

Dormant grape (Vitis vinifera L.) cuttings were removed from cold storage (3°C) and incubated at 25°C or 45°C for 30 minutes (heat shock treatment), followed by four hours at 25°C. Control cuttings were held at 3°C. Bud proteins were separated by two-dimensional electrophoresis. Thirty-two proteins accumulated following heat shock at 25°C, and 112 accumulated following heat shock at 45°C. Relative to the control, 10 proteins decreased in the 25°C heat shocked buds, but were present at similar or greater concentrations in the 45°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°C heat shocked buds. The 25°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°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°C for 4.5 hours has been shown to confer increased thermotolerance. Heat shock at 45°C, which confers greater thermotolerance, is correlated with increased expression of HSP70 as well as other proteins.