Engineering of the rose flavonoid biosynthetic pathway successfully generated blue-hued flowers accumulating delphinidin.
Flower color is mainly determined by anthocyanins. Rosa hybrida lacks violet to blue flower varieties due to the absence of delphinidin-based anthocyanins, usually the major constituents of violet and blue flowers, because roses do not possess flavonoid 3',5'-hydoxylase (F3'5'H), a key enzyme for delphinidin biosynthesis. Other factors such as the presence of co-pigments and the vacuolar pH also affect flower color. We analyzed the flavonoid composition of hundreds of rose cultivars and measured the pH of their petal juice in order to select hosts of genetic transformation that would be suitable for the exclusive accumulation of delphinidin and the resulting color change toward blue. Expression of the viola F3'5'H gene in some of the selected cultivars resulted in the accumulation of a high percentage of delphinidin (up to 95%) and a novel bluish flower color. For more exclusive and dominant accumulation of delphinidin irrespective of the hosts, we down-regulated the endogenous dihydroflavonol 4-reductase (DFR) gene and overexpressed the Irisxhollandica DFR gene in addition to the viola F3'5'H gene in a rose cultivar. The resultant roses exclusively accumulated delphinidin in the petals, and the flowers had blue hues not achieved by hybridization breeding. Moreover, the ability for exclusive accumulation of delphinidin was inherited by the next generations.
Katsumoto
Yukihisa
Y
Suntory Limited Research Center, Institute for Plant Science, 1-1-1 Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka, 618-8503 Japan. Yoshikazu_Tanaka@suntory.co.jp
Fukuchi-Mizutani
Masako
M
Fukui
Yuko
Y
Brugliera
Filippa
F
Holton
Timothy A
TA
Karan
Mirko
M
Nakamura
Noriko
N
Yonekura-Sakakibara
Keiko
K
Togami
Junichi
J
Pigeaire
Alix
A
Tao
Guo-Qing
GQ
Nehra
Narender S
NS
Lu
Chin-Yi
CY
Dyson
Barry K
BK
Tsuda
Shinzo
S
Ashikari
Toshihiko
T
Kusumi
Takaaki
T
Mason
John G
JG
Tanaka
Yoshikazu
Y
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism; D000872:Anthocyanins / Q000737:chemistry / Q000378:metabolism*; D005419:Flavonoids / Q000096:biosynthesis* / Q000737:chemistry; D035264:Flowers / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010641:Phenotype; D010860:Pigments, Biological / Q000737:chemistry / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D027826:Rosa / Q000235:genetics / Q000378:metabolism*
D000872:Anthocyanins; D005419:Flavonoids; D010860:Pigments, Biological; D010940:Plant Proteins; D000429:Alcohol Oxidoreductases; C056570:dihydroflavanol 4-reductase; C017185:delphinidin