Sugar Alcohols and Osmotic Stress Adaptation in Plants

Sugar alcohols or polyols are derivatives of sugars produced in high amounts during salt or drought (abiotic) stress in plants. A number of sugar alcohols identified in plants include manitol, sorbitol, D-ononitol, pinitol, adonitol, ribitol, glucitol etc., which are classified as cyclic and non-cyclic polyols. Osmoregulation is a phenomenon of regulating constant fluid osmotic pressure in cells through salt and water concentrations during abiotic stress conditions. In plants, abiotic stress induces water loss, and at the same time, they release osmolytes including sugar alcohols which maintains osmoregulation. Sugar alcohols play a crucial role in osmotic adaptations and exert tolerance to salt and drought stress in plants. Due to the importance of sugar alcohols in crop improvement its metaolism, osmotic adaptations and role of transformational studies are discussed in the present chapter.