EXPRESSION OF HEAT-SHOCK PROTEINS IN DORMANT BUDS OF GRAPE (VITIS-VINIFERA L.)

Dormant grape (Vitis vinifera L.) cuttings were removed from cold stor age (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 separa ted by two-dimensional electrophoresis. Thirty-two proteins accumulate d following heat shock at 25 degrees C, and 112 accumulated following heat shock at 45 degrees C. Relative to the control, 10 proteins decre ased in the 25 degrees C heat shocked buds, but were present at simila r 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 tw o of the isoforms (pIs 5.86, and 5.90) in the 45 degrees C heat shocke d 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 shoc k at 25 degrees C raises the possibility that changes in the protein p rofile 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 incr eased thermotolerance. Heat shock at 45 degrees C, which confers great er thermotolerance, is correlated with increased expression of HSP70 a s well as other proteins.