Relationships between freezing resistance and biochemicals in grapevine buds and canes: Different soluble carbohydrates accumulate in several cultivars during cold acclimation

Owing to recent warming trends during the growing season, wine grapevine (Vitis vinifera) production has increased in subarctic areas such as Hokkaido. However, high freezing resistance remains essential for grapevines due to the severe winter temperatures in these regions. Here, we investigated the seasonal variation in freezing resistance, as well as the water, soluble carbohydrate, proline, and total phenolic content (TPC) in the buds and canes of two V. vinifera cultivars and a Vitis riparia hybrid, Maeve. We found that freezing resistance in the buds and canes increased from fall to winter, with Maeve exhibiting higher freezing resistance than the V. vinifera cultivars during both seasons. Maeve experienced a faster rate of deacclimation, leading to comparable spring freezing resistance among all cultivars. The water content in the buds and canes of all three cultivars decreased during the fall, with Maeve showing an earlier reduction compared to the others. Most soluble carbohydrates increased in winter and decreased in spring. Notably, Maeve, which had higher winter freezing resistance, accumulated more sucrose in its buds and a higher concentration of soluble carbohydrates, particularly monosaccharides, in its canes compared to the other two cultivars. Proline and TPC levels were not linked to freezing resistance. Grapevine buds and canes appeared to accumulate soluble carbohydrates, especially monosaccharides, during winter, while reducing water content in fall to enhance freezing resistance. This study suggests that grapevine cultivars in Hokkaido may utilize different types of soluble carbohydrates to improve the freezing resistance of their buds and canes.