In order to investigate the effects of heat shock proteins (HSPs) on walnuts under low temperature stress, first of all low temperature tolerances of ten walnut cultivars (Chandler, Fernor, Franquette, Pedro, Bilecik, Kaman-I, Kaman-II, Kaman-III, Şebin and Yalova I) were determined. One-year-old shoot samples were taken from the plants in two different periods, cold-acclimated (CA) and non-acclimated (NA), and were exposed to +5 °C, -5 °C, -15 °C and -25 °C for 12 h. Cold injury was determined by ion leakage analysis in the thawed bark tissues. According to the results of this analysis, two cultivars were determined as cold sensitive (Chandler) and cold tolerant (Fernor) in terms of low-temperature tolerance.
In order to examine the effects of HSPs on cold tolerance in walnut, the protein profiles, the amount of total protein and HSPs of these two varieties were determined. As a result of the immunoblot analysis, it was determined that 44 kDa HSP23 and 59 kDa HSP60 are responsible for low temperature tolerance in walnuts.