HIGH-LEVEL FRUCTAN ACCUMULATION IN A TRANSGENIC SUGAR-BEET

have transformed sugar beet into a crop that produces fructans. The ge ne encoding 1-sucrose:sucrose fructosyl transferase (1-SST), which was isolated from Helianthus tuberosus, was introduced into sugar beet. I n H. tuberosus, 1-SST mediates the first steps in fructan synthesis th rough the conversion of sucrose (GF) into low molecular weight fructan s GF(2), GF(3), and GF(4). In the taproot of sugar beet transformed wi th the 1-sst gene, the stored sucrose is almost totally converted into low molecular weight fructans. In contrast, 1-sst expression in the l eaves resulted in only low levels of fructans. Despite the storage car bohydrate having been altered, the expression of the 1-sst gene did no t have any visible effect on phenotype and did not affect the growth r ate of the taproot as observed under greenhouse conditions.