Isolation of cDNAS encoding tetrahydroxychalcone 2'- glucosyltransferase activity from carnation, cyclamen, and catharanthus

Abstract

4,2',4',6'-Tetrahydroxychalcone (THC) 2'-glucoside that confers yellow color to the petals of carnation, cyclamen, and catharanthus is biosynthesized by the action of UDP-glucose-dependent THC 2'-glucosyltransferase (THC2'GT). We isolated 18 types of full-length cDNA encoding GT-like sequences from carnation petals. Expression of these cDNA in Escherichia coli identified five cDNAs encoding THC2'GT that were different from the previously isolated THC2'GT. We also isolated a cDNA encoding THC2'GT from both catharanthus and cyclamen. These THC2'GT cDNAs were introduced to petunia. Transgenic petunia that expressed three of the GTs produced THC 2'-glucoside, which indicated that they function as THC2'GT in vivo. These cDNAs could be useful molecular tools to yield yellow flower color, although the amount accumulated in the transgenic petals was too small to alter the flower color in this study.