Distribution, metabolism and role of sorbitol in higher plants. A review.

Sorbitol is one of the 17 sugar alcohols or alditols found in higher plants. It is a major final product of photosynthesis and, together with sucrose, represents the main form of carbon translocated in many species of the Rosaceae and Plantaginaceae families. Sorbitol accumulation is considered as an adaptative response of plants to drought, salinity or chilling stress. Biosynthesis of sorbitol is confined mainly to source leaves whereas metabolic utilization is restricted to sink tissues. Sorbitol synthesis is in competition with sucrose synthesis because they have a common pathway from triosephosphate to glucose-g-phosphate. The control mechanisms of cellular carbon partitioning into sorbitol versus sucrose and starch in source leaves remains unknown. However partitioning appears to be affected by environmental factors.