ACCUMULATION OF FRUCTOSE POLYMERS IN TRANSGENIC TOBACCO

Fructan, a polyfructose molecule, is a storage compound in a limited n umber of plant species. Usually these species accumulate fructan with a low degree of polymerization (DP) and most of these plants have prop erties which preclude their use as a fructan source. With the eventual aim of allowing the accumulation of high DP fructans in non-fructan s toring plants, we have investigated whether carbohydrate how in the pl ant cell can be directed to produce this polymer. For this purpose the SacB gene from Bacillus subtilis, which encodes levansucrase, was mod ified and introduced into tobacco plants. Transgenic plants containing the sacB gene accumulate fructans. The size and properties of this fr uctan are similar to fructan produced by Bacillus subtilis, and is sta ble in plants. Although the level of fructan accumulation in the trans genic tobacco plants ranged from 3-8 percent of the dry weight, no lev ansucrase mRNA or protein could be detected in these plants. Extension of this work should permit the production of this high molecular weig ht biopolymer in crop plants for applications in food and non-food pro ducts.