ABSTRACT
Sugar alcohols are aldose and ketose sugars that have been reduced to straight or branched chain polyhydric alcohols. Osmotic and cold stress effects suggest that sugar alcohol metabolism might be regulated in response to drought stress. Sinks, for example, have little or no capacity to synthesize sugar alcohols. Studies of sink—source transitions can provide excellent insight into the relative roles that specific enzymes and processes play in plant metabolism. In all sugar alcohol-producing higher plants studied to date, sucrose is present and frequently the major photoassimilate. The sugar alcohols represent the majority of the photosynthetic carbon pools in leaves and other vegetative tissues. Sugar alcohols were shown to be primary photosynthetic products in higher plants. Evidence for translocation of other acyclic sugar alcohols is lacking, although the cyclitol inositol may be present in trace amounts in most phloem exudates. Sugar alcohol transport in the sink systems appears to have some characteristics common to those reported for sucrose in sink tissues.
