Transgenic potato (Solanum tuberosum) tubers synthesize the full spectrum of inulin molecules naturally occurring in globe artichoke (Cynara scolymus) roots

The ability to synthesize high molecular weight inulin was transferred to p otato plants via constitutive expression of the 1-SST (sucrose:sucrose 1-fr uctosyltransferase) and the 1-FFT (fructan: fructan 1-fructosyltransferase) genes of globe artichoke (Cynara scolymos). The fructan pattern of tubers from transgenic potato plants represents the full spectrum of inulin molecu les present in artichoke roots as shown by high-performance anion exchange chromatography. as well as size exclusion chromatography. These results dem onstrate in planta that the enzymes sucrose:sucrose 1-fructosyltransferase and fructan:fructan 1-fructosyltransferase are sufficient to synthesize inu lin molecules of all chain lengths naturally occurring in a given plant spe cies. Inulin made up 5% of the dry weight of transgenic tubers, and a low l evel of fructan production also was observed in fully expanded leaves. Alth ough inulin accumulation did not influence the sucrose concentration in lea ves or tubers, a reduction in starch content occurred in transgenic tubers, indicating that inulin synthesis did not increase the storage capacity of the tubers.