Mannitol, a six carbon sugar alcohol, has heretofore received little a
ttention from plant scientists, despite its wide distribution in natur
e. However, recent findings concerning the biochemistry and physiology
of higher plants indicate that species that metabolize mannitol have
several advantages over those that exclusively translocate sugars. One
advantage is increased tolerance to salt- and osmotic-stress as a res
ult of mannitol's function as a 'compatible solute'. Another advantage
is a possible role in plant responses to pathogen attack - thus manni
tol metabolism may play roles in plant responses to both biotic and ab
iotic stresses.