Inulin chain length modification using a transgenic approach opening new perspectives for chicory

Chicory capable of synthesizing long-chain inulin is of great interest. During the growing season, the sucrose-sucrose 1-fructosyltransferase (1-SST) activity is vital for production of long-chain inulin in chicory. With the purpose to increase inulin chain length, we employed Agrobacterium-mediated transformation method. Transgenic chicory plants (Cichorium intybus L. var. sativum) cv. 'Melci' has been developed to overexpress sucrose-sucrose 1-fructosyltransferase (1-SST) under the control of the CaMV 35S promoter. The integration of the T-DNA into the plant genome was confirmed by PCR on genomic DNA using gene-specific primers. Quantification of the 1-SST transcript expression level revealed that transgenic plants showed higher 1-SST expression than those in non-transgenic plants. Further analyses proved that the fructan content of the roots significantly increased in the transgenic plants. These results revealed that overexpression of the 1-SST, the key gene in inulin biosynthesis in chicory, might serve as a novel approach to develop plants with the long-chain inulin content.