Cyclitol production in transgenic tobacco

High levels of cyclic sugar alcohols (cyclitols) correlate with tolerance to osmotic stress in a number of plant species. A gene encoding a cyclitol biosynthesis enzyme from a halophyte, Mesembryanthemum crystallinum has been introduced into tobacco. The gene, lmt1 , encodes a myo ‐inositol O ‐methyl transferase that, in M. crystallinum , catalyzes the first step in the stress‐induced accumulation of the cyclitol pinitol. Tobacco transformed with the lmt1 cDNA under the control of the CaMV 35S promoter appeared phenotypically normal and exhibited IMT1 enzyme activity. Transformants accumulated a carbohydrate product not detectable in non‐transformed control plants. This product was identified by HPLC and NMR as ononitol (1‐ d ‐4‐ O ‐methyl myo ‐inositol). Ononitol was a major carbohydrate constituent…