Fig. 1 Natural occurrence of different flower colors in azalea (
flowers with different colors were found in a same branch. (
) A small sector with red color was
found in the white background of the petal. (
) A red flower was found in a cluster of white
) A typical chimeric flower composed of two sectors of white and red colors.
Fig. 2 Representative structures of pigments.
carotene) belongs to carotenoids, and contributes reddish yellow
color in some flowers. Betacyanin (red to red-violet color) and
betaxanthin (yellow color) are two groups of betalains, which
contribute flower pigmentation in several plants of a small group in
the order Caryophyllales. Flavonoid is the major contributor in
flower color in plant species. Flavonoid consists of two aromatic
rings (A and B), and a heterocyclic C ring with oxygen.
Molecular Breeding of Flower Color
• Chen-Kuen Wang
Institute of BioAgricultural Sciences, Academia Sinica, Taipei 115, Taiwan
anthocyanin, betalain, carotenoid, flavonoid, flower color, genetic engineering, pigmentation
Flower color contributes mainly to the market value of an ornamental plant, and coloration of flowers is determined by three classes of pigments:
flavonoids, carotenoids and betalains. Flavonoids and carotenoids are widespread; however, betalains can be found only in plants of several
genera in the order Caryophyllales, which belongs to one small group of angiosperms. Among these pigments, flavonoids (mainly anthocyanins)
are the most common flower pigments contributing to a range of colors from yellow to orange to red to purple. During the past few decades,
flavonoid biosynthetic pathway leading to anthocyanin production has been well established in various plant species, and genetic engineering of
flavonoid/anthocyanin biosynthesis has been used to produce cultivars with novel pigmentation in flowers. Here we summarize the current status
of molecular approaches in breeding flower coloration, and describe our study and prospective regarding flower color modification.
Flower color is one of the most attractive characteristics in ornamental plants, contributing to the major value in the floricultural market. In nature,
various patterns regarding to the flower color can be easily observed (
); however, most of these phenotypic changes are not transmittable
and thus novel varieties with commercial value cannot be obtained. Furthermore, alteration in flower pigmentation is a visible indicator to study
expression and regulation of floral genes in plant molecular biology. Thus, examination and manipulation of flower color is not only important in
basic research areas, it also has a great benefit in biotechnological applications.
Generally speaking, flower color is predominantly determined by two classes of pigments: flavonoids and carotenoids. Flavonoids (mainly