The invention concerns the use of a DNA sequence coding for a polyol carrier, in plants and fungi, such as polyols having a main chain containing 5 to 8 carbon atoms, in particular 5 to 7 carbon atoms, more preferably 6 carbon atoms, the polyols being advantageously selected among mannitol, sorbitol, dulcitol, galactitol, inositol, myo-inositol, ribitol and xylitol, and being preferably mannitol, for preparing transgenic plants.