Seasonal Changes of the Metabolites in the Leaves, Bark and Xylem Tissues of Olive Tree (Olea europaea. L) II. Carbohydrates

Seasonal changes of starch and soluble carbohydrates in leaves, bark and xylem tissues of olive tree were examined during a complete annual cycle. Leaf starch and soluble carbohydrates were detected at high levels during the spring and autumn metabolically active periods. The low level of leaf starch in combination with the drastic reduction of soluble carbohydrates and mannitol, defined the summer period of the low metabolic state of the tree. The low leaf starch level in conjunction with the risen soluble carbohydrate levels in leaves in winter were associated with cold acclimation processes. The bark and xylem tissues were performing as starch deposition sites, and differences in the extent of starch accumulation in these tissues were detected during the seasons. The starch fluctuations in bark and xylem were discussed in relation to the translocation of metabolites and other physiological processes. Mannitol, the most abundant leaf carbohydrate, was examined in relation to the reducing sugars exported to the bark. The bark mannitol was examined in conjunction with the sucrose, glucose and starch levels in the maturing bark tissues and was correlated to the low winter temperatures. During the winter there was a drastic reduction of mannitol circulation from the bark to xylem.