FRUCTAN OF THE INULIN NEOSERIES IS SYNTHESIZED IN TRANSGENIC CHICORY PLANTS (CICHORIUM-INTYBUS L) HARBORING ONION (ALLIUM-CEPA L) FRUCTAN-FRUCTAN 6G-FRUCTOSYLTRANSFERASE

Fructan (polyfructosylsucrose) is an important storage carbohydrate in many plant families. fructan:fructan 6G-fructosyltransferase (6G-FFT) is a key enzyme in the formation of the inulin neoseries, a type of f ructan accumulated by members of the Liliales. We have cloned the 6G-F TT from onion by screening a cDNA library using barley sucrose:fructan 6-fructosyltransferase (6-SFT) as a probe. The deduced amino acid seq uence showed a high homology with plant invertases and 6-SFT. Incubati on of protein extracts from transgenic tobacco plants with the trisacc haride 1-kestose and sucrose resulted in the formation of neokestose a nd fructans of the inulin neoseries with a degree of polymerization up to six. Introduction of the onion 6G-FFT into chicory resulted in the synthesis of fructan of the inulin neoseries, in addition to the synt hesis of linear inulin.