Abstract
Two types of red pigments, anthocyanins and betacyanins, never occur together in the same plant. Nevertheless of the lack of anthocyanin, other flavonoids, especially major flavonols are widely found in the Caryophyllales. This suggests that the step(s) of anthocyanin biosynthesis from dihydroflavonols to anthocyanins could be blocked in the Caryophyllales.
We have isolated cDNA of DFR (dihydroflavonol 4-reductase) from Spinacia oleracea and Phytolacca americana, plants of the Caryophyllales. These DFR showed high degree of homology (62-82% identity) with DFRs of anthocyanin-producing plants. A putative NADPH binding region, which is likely part of the co-factor binding site, was located at the N-terminal in both of DFRs.
Both of recombinant DFRs expressed in E. coli converted dihydroquercetin to leucocyanidin. This indicates functional DFR is expressed in Spinacia oleracea and Phytolacca americana, which are the Caryophyllales.
