Carbohydrate Composition and Freezing Tolerance of Canes and Buds in Vitis vinifera

In grapevines, buds and canes have different strategies of freezing tolerance - buds avoid freezing by supercooling, whereas canes tolerate extracellular freezing. To further understand the relationship between freezing tolerance and carbohydrate composition of these tissues in Vitis vinifera, analyses were made of starch, glucose, fructose, sucrose and raffinose of field-grown vines during natural acclimation and deacclimation over two years, on artificially deacclimated field material, and on daylength induced dormant growthroom material. Statistics on correlation and path coefficients were calculated to detect relationships, and a was set at 0.05.During the acclimation and deacclimation of grapevines in the field, the level of most carbohydrates was correlated with freezing tolerance in both buds and canes. Starch levels were negatively correlated with hardiness whereas most soluble sugars were positively correlated. Artificial deacclimation with heat treatment supported these relationships between LTSo and carbohydrates. Dormancy induction by short day treatment did not increase freezing tolerance but did increase raffinose in buds. Statistical path analysis highlighted the importance of starch and fructose in freezing tolerance of grapevines, and indicated that the different soluble sugars may have different roles in buds and canes. This statistical method holds great potential, particularly for identifying transformation targets from data on metabolites.