Cloning and Sequencing of the cDNA of UDPG-glucosyltransferase from Stevia rebaudiana

By using two homologous degenerated primers, DNA fragments encoding steviol UDPG glucosyltransferase were amplified from the leaves of Stevia rebaudiana. The DNA fragment with strong homology to known flavonoid glucosyltransferases was used to design two primers to amplify upstream and downstream cDNA of stevia glucosyltransferase. The cDNA of stevia glucosyltransferase sudpg-2 was 1 662 bp in length, with a poly(A) tail and a 1 362 bp open reading frame which encoded 454 deduced amino acid residues. The deduced amimo acids sequence has 40%～60% identity to other plant glucosyltransferase and includes a part of the glucosyltransferase signature sequence. Molecular phylogenic relations of the deduced amino acids sequences with other plant glucosyltransferase suggested that the steviol UDPG glucosyltransferase belongs to family of flavonoid glucosyltransferases.