Articles
THE LONG, WINDING GENETIC MODIFICATION PATH TO MORE COLOURFUL FLOWERS; BLUE, RED AND YELLOW
Article number
836_5
Pages
41 – 48
Language
English
Abstract
Flower breeding is constrained by the limited gene sources available within a target species.
Molecular breeding utilizing genetic engineering techniques has liberated breeders from this gene-pool constraint.
For successful molecular breeding, it is necessary to isolate relevant genes, establish transformation systems, optimize expression of transgenes and obtain regulatory permission for both production and consumption.
Though all these procedures are very often expensive and time con¬suming, the investment is long-term and a financial return is possible for transgenic flowers that meet the consumers demand.
We have been developing transgenic flowers, with modified flower colour, for many years.
Flavonoids and the coloured sub-class of compounds, anthocyanins, are dominant colour constituents of most flowers.
It is feasible to generate white, yellow, red and blue flowers by engineering the pathway; both by over-expression of heterologous genes and/or down-regulation of endogenous genes.
The major cut-flower species rose, carnation and chrysanthemum, lack blue/violet cultivars because they do not accumulate the delphinidin-based anthocyanins that are present in most blue/violet flowers.
Flavonoid 3,5-hydroxylase (F35H) is the critical enzyme for delphinidin biosynthesis and this gene is missing in species that do not accumulate delphinidin-based anthocyanins.
An efficient transformation system was developed for rose and carnation and after introduction of the gene encoding F35H, transgenics were produced whose flowers accumulated delphinidin- based anthocyanins and an altered colour.
Through careful choice of host cultivar and optimization of the expression of transgenes it has been possible to obtain flowers which accumulate delphinidin-based anthocyanins only.
Such flowers exhibit an attractive colour change to blue/violet.
Transgenic colour-modified carnation has been available commercially since 2000 and the first commercially available, colour- modified rose variety will be sold in 2009. From a biosafety perspective, the transgenic flower have no impact on the environment or health and the varieties pose negligible, if any, risk to biodiversity.
Molecular breeding utilizing genetic engineering techniques has liberated breeders from this gene-pool constraint.
For successful molecular breeding, it is necessary to isolate relevant genes, establish transformation systems, optimize expression of transgenes and obtain regulatory permission for both production and consumption.
Though all these procedures are very often expensive and time con¬suming, the investment is long-term and a financial return is possible for transgenic flowers that meet the consumers demand.
We have been developing transgenic flowers, with modified flower colour, for many years.
Flavonoids and the coloured sub-class of compounds, anthocyanins, are dominant colour constituents of most flowers.
It is feasible to generate white, yellow, red and blue flowers by engineering the pathway; both by over-expression of heterologous genes and/or down-regulation of endogenous genes.
The major cut-flower species rose, carnation and chrysanthemum, lack blue/violet cultivars because they do not accumulate the delphinidin-based anthocyanins that are present in most blue/violet flowers.
Flavonoid 3,5-hydroxylase (F35H) is the critical enzyme for delphinidin biosynthesis and this gene is missing in species that do not accumulate delphinidin-based anthocyanins.
An efficient transformation system was developed for rose and carnation and after introduction of the gene encoding F35H, transgenics were produced whose flowers accumulated delphinidin- based anthocyanins and an altered colour.
Through careful choice of host cultivar and optimization of the expression of transgenes it has been possible to obtain flowers which accumulate delphinidin-based anthocyanins only.
Such flowers exhibit an attractive colour change to blue/violet.
Transgenic colour-modified carnation has been available commercially since 2000 and the first commercially available, colour- modified rose variety will be sold in 2009. From a biosafety perspective, the transgenic flower have no impact on the environment or health and the varieties pose negligible, if any, risk to biodiversity.
Publication
Authors
Y. Tanaka, S. Chandler
Keywords
anthocyanin, carnation, flower colour, genetic engineering, rose
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