Engineering of the Rose Flavonoid Biosynthetic Pathway Successfully Generated Blue-Hued Flowers Accu.pdf
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Engineering of the Rose Flavonoid Biosynthetic Pathway Successfully
Generated Blue-Hued Flowers Accumulating Delphinidin
Yukihisa Katsumoto 1, Masako Fukuchi-Mizutani 1, Yuko Fukui 1, Filippa Brugliera 2, Timothy A. Holton 2,
Mirko Karan 2, Noriko Nakamura 1, Keiko Yonekura-Sakakibara 1, 3, Junichi Togami 1, Alix Pigeaire 2,
Guo-Qing Tao 2, Narender S. Nehra 2, Chin-Yi Lu 2, Barry K. Dyson 2, Shinzo Tsuda 1,
Toshihiko Ashikari 1, 2, Takaaki Kusumi 1, John G. Mason 2 and Yoshikazu Tanaka 1, *
1 Suntory Limited Research Center, Institute for Plant Science, 1-1-1 Wakayamadai, Shimamoto-cho, Mishima-gun, Osaka, 618-8503 Japan
2 Florigene Pty. Ltd, 1 Park Drive, Bundoora, VIC 3083, Australia
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 consti-
tuents of violet and blue flowers, because roses do not possess
flavonoid 30,50-hydoxylase (F3050H), 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 F3050H 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 Iris3hollandica DFR gene in addition to
the viola F3050H 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
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