Abstract
Ice nucleation is considered to be an important mechanism in cold hardy plant tissues to avoid excess supercooling of protoplasm and properly induce extracellular freezing and to accommodate ice crystals in the specific tissues in extra-organ freezing. However, there have been only a few studies on ice nucleating activity (INA) associated with wintering plants. We characterized highINA in cold hardy twigs. The INA in the twig was localized in bark where it was tightly bound to cell walls fraction while intracellular fractions had much less INA. The presence of high INA in cell walls fraction of stem bark corresponds well to the freezing behavior (extracellular freezing) of the bark tissues, high temperature exotherm detected in differential thermal analysis and ice accumulation in the bark tissues. The stem INA tended to decrease when measured after the stem was frozen to deeper temperatures. The stem INA was resistant to various antimicrobial treatments.
