Cymbidium hybrida dihydroflavonol 4-reductase does not efficiently reduce dihydrokaempferol to produce orange pelargonidin-type anthocyanins.
Some angiosperms are limited to a range of possible flower colors. This limitation can be due to the lack of an anthocyanin biosynthetic gene or to the substrate specificity of a key anthocyanin biosynthetic enzyme, dihydroflavonol 4-reductase (DFR). Cymbidium hybrida orchid flowers primarily produce cyanidin-type (pink to red) anthocyanins and lack the pelargonidin-type (orange to brick-red) anthocyanins. To investigate the underlying molecular mechanism of this flower color range, we cloned a Cymbidium DFR gene and transformed it into a DFR- petunia line. We found that the Cymbidium DFR did not efficiently reduce dihydrokaempferol (DHK), which is an essential step for pelargonidin production. Phylogenetic analysis of a number of DFR sequences indicate that the inability to catalyze DHK reduction has occurred at least twice during angiosperm evolution. Our results indicate that developing a pelargonidin-type orange flower color in Cymbidium may require the transformation of a DFR gene that can efficiently catalyze DHK reduction.
Kumho Life and Environmental Science Laboratory, Kwangju, Korea.
E T
ET
Johnson
H
H
Yi
B
B
Shin
B J
BJ
Oh
H
H
Cheong
G
G
Choi
D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000096:biosynthesis*; D002384:Catalysis; D005419:Flavonoids; D008969:Molecular Sequence Data; D010802:Phylogeny; D010944:Plants / Q000201:enzymology*; D030821:Plants, Genetically Modified; D011794:Quercetin / Q000031:analogs & derivatives* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D000872:Anthocyanins; D005419:Flavonoids; C080220:aromadedrin; D011794:Quercetin; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase