GM Crop Database

Database Product Description

959A, 988A, 1226A, 1351A, 1363A, 1400A
Host Organism
Dianthus caryophyllus (Carnation)
Trait
Modified flower colour; Sulfonylurea herbicide tolerance, specifically triasulfuron and metsulfuron-methyl.
Trait Introduction
Agrobacterium tumefaciens-mediated plant transformation.
Proposed Use

Production for the cut-flower industry.

Product Developer
Florigene Pty Ltd.

Summary of Regulatory Approvals

Country Food Feed Environment Notes
Colombia 2000
European Union 1998

Introduction Expand

Transgenic lines 959A, 988A, 1226A, 1351A, 1363A, and 1400A were developed using recombinant DNA techniques to produce flowers with a unique deep purple colour by introducing two genes that function together in the biosynthesis of the anthocyanin pigment delphinidin. The transgenic lines were derived from the parent cultivar ‘White Unesco’, which is a white coloured carnation that was selected for a mutation in the dihydroflavonol reductase (DFR) encoding gene that did not allow for expression of a functional enzyme, and thus did not produce the anthocyanin type pigments that give rise to blue and red coloured flowers. The two genes introduced into the transgenic carnation lines included a functional dihydroflavonol reductase encoding gene isolated from petunia (Petunia hybrida) and a gene encoding the enzyme flavonoid 3’, 5’-hydroxylase (F3’, 5’H), a member of the NADPH-Cytochrome P450 reductase family, isolated from Viola. Expression of the F3’, 5’H encoding gene (bp40) allows for the production of blue coloured delphinidin anthocyanin pigments, which are not normally found in carnations.

An additional gene encoding a variant form of the enzyme acetolactate synthase (ALS) was also introduced into this transgenic carnation line in order to confer the trait of tolerance to sulfonylurea type herbicides (e.g., chlorsulfuron, commonly known as Glean™), which are potent inhibitors of ALS. Acetolactate synthase (also known as acetohydroxy acid synthase; AHAS) is involved in the conversion of threonine to alpha-aceto-alpha-hydroxybutyrate and pyruvate to alpha-acetolactate, which are key precursors in the biosynthesis of the essential branched chain amino acids isoleucine and valine, respectively. Alpha-acetolactate is also a precursor in the synthesis of leucine. The variant form of ALS introduced into this carnation line was isolated from a chlorsulfuron tolerant tobacco (Nicotiana tabacum). This trait was introduced as a means of selecting for transformed plants during tissue culture regeneration as sulfonylurea herbicides are not, and will not be, used in the carnation industry.

Summary of Introduced Genetic Elements Expand

Code Name Type Promoter, other Terminator Copies Form
dfr dihydroflavonol reductase PM native promoter from Petunia native terminator
surB acetolactate synthase HT CaMV 35S surB terminator from N. tabacum
bp40 flavonoid 3p, 5p hydroxylase PM petal specific CHS promoter derived form Petunia hybrida. D8 terminator derived from Petunia hybrida

Characteristics of Dianthus caryophyllus (Carnation) Expand

Center of Origin Reproduction Toxins Allergenicity

The species is native to the Mediterranean region, including Europe, Asia, and northern Africa.

Carnation flowers are pollinated primarily by butterflies and sometimes by other insects.

The parts of the carnation plants are not thought to be toxic, and the flowers are considered edible.

Occupational exposure to carnation flowers has been associated with allergic reactions in humans.

Modification Method Expand

The transgenic carnation lines 959A, 988A, 1226A, 1351A, 1363A, and 1400A were produced by Agrobacterium-mediated transformation of carnation plants (Dianthus caryophyllus L., cultivar ‘White Unesco’) in which the transfer-DNA (T-DNA) region of the bacterial Ti plasmid was modified to contain the DFR and F3’, 5’H encoding genes as well as the surB (ALS encoding) gene from a chlorsulfuron tolerant line of tobacco.

Expression of the DFR encoding gene was under the control of its own promoter and terminator sequences. Expression of the F3’, 5’H encoding gene was under the control of the petal-specific chalcone synthase (CHS) promoter and the D8 terminator, both derived from Petunia hybrida.

The surB gene was used as a selectable marker to identify transformed plants during tissue culture regeneration. Expression of the ALS enzyme was regulated using the CaMV 35S promoter and the surB terminator derived from tobacco (Nicotiana tabacum).

Characteristics of the Modification Expand

Genetic Stability of the Introduced Trait

The genes encoding DFR and F3’, 5’H, as well as the surB marker gene, were stably integrated into the transgenic carnation lines 959A, 988A, 1226A, 1351A, 1363A, and 1400A. These transgenic lines were reproduced through vegetative reproduction, as were their progeny, as well as progeny derived through crosses with traditionally bred non-genetically modified carnation plants.

Environmental Safety Considerations Expand

Outcrossing

The commercial standard carnation varieties are generally male sterile and rarely produce anthers. In fertile flowers, little pollen is produced, and cross-pollination is only via insects. In commercial carnation production, outcrossing is unlikely as flowers are cut before opening. Should flowers open, only certain insects are easily able to access nectaries in flowers and there are very few opportunities for this to occur during transit and sale. Furthermore, carnations plants require 6 weeks for seed development. A genetically modified cut carnation flower lasts only 3-4 weeks.
Many Dianthus species occur as common wildflowers. There has never been any evidence of hybridization between carnation and these species, nor after decades of cultivation have carnations been found in the wild. The biology of carnation is such that there are no realistic ways for the genetically modified plants to escape from cultivation and become established as populations in the wild, or for gene dispersal from the genetically modified carnation to occur.

Weediness Potential

Genetically modified carnation lines 959A, 988A, 1226A, 1351A, 1363A, and 1400A, and derived lines, have little potential to become weeds. After decades of cultivation, carnations have never been found in the wild. Carnation has no weedy characteristics and is not closely related to known weeds.

Impact on Biodiversity

The risk of transferring genetic traits from transgenic carnation lines 959A, 988A, 1226A, 1351A, 1363A, and 1400A to species in unmanaged environments was insignificant. These transgenic carnation lines are intended for cultivation by growers, flower auctions, flower wholesalers, retailers and breeders. Plants are sold as flowers, cuttings or whole plants.

Abstract Collapse

Carnations (Dianthus carophyllus L.) are among the most extensively grown cut flowers with more than 10 billion carnations produced around the world each year. Carnations are cultivated by growers, flower auctions, flower wholesalers, retailers and plant breeders worldwide and are sold as cut flowers, cuttings or plants.

Plant breeders are always in search of developing a new flower variety with a novel colour. However, for some flower varieties, no amount of traditional breeding will achieve blue, violet, or mauve flowers, due to the inability of the plant to form certain pigments. There are two major types of flower pigments: the flavonoids, which contribute to a range of colours from yellow to red to blue, and; the carotenoids, which are common pigments in flowers with colours ranging from yellow to orange. The flavonoids include the anthocyanin pigments, cyanidin (red), pelargonidin (brick red), and delphinidin (blue). Carnations, roses, lilies, chrysanthemums and gerberas, which represent 75 percent of worldwide flower sales, do not produce the blue pigment called delphinidin.

Transgenic lines 959A, 988A, 1226A, 1351A, 1363A, and 1400A were developed using recombinant DNA techniques to produce flowers with a unique deep purple colour by introducing two genes that function together in the biosynthesis of the anthocyanin pigment delphinidin. The transgenic lines were derived from the parent cultivar ‘White Unesco’, which is a white coloured carnation that was selected for a mutation in the dihydroflavonol reductase (DFR) encoding gene that did not allow for expression of a functional enzyme, and thus did not produce the anthocyanin type pigments that give rise to blue and red coloured flowers. The two genes introduced into the transgenic carnation lines included a functional dihydroflavonol reductase encoding gene isolated from petunia (Petunia hybrida) and a gene encoding the enzyme flavonoid 3’, 5’-hydroxylase (F3’, 5’H), a member of the NADPH-Cytochrome P450 reductase family, isolated from Viola. Expression of the F3’, 5’H encoding gene (bp40) allows for the production of blue coloured delphinidin anthocyanin pigments, which are not normally found in carnations.

The biology of carnation is such that there are no reasonable means for the genetically modified plants to escape from cultivation and become established as populations in the wild, or for gene dispersal from the genetically modified carnation to occur. The commercial standard carnation varieties are generally male sterile and rarely produce anthers; and if they do, little pollen is produced and this can only be transferred by insects. In commercial carnation production, outcrossing is unlikely as flowers are cut before opening. Should flowers open, only certain insects are easily able to access nectaries in flowers and there are very few opportunities for this to occur during transit and sale. Furthermore, carnations plants require 6 weeks for seed development. A genetically modified cut carnation flower lasts only 3-4 weeks, which is not enough time for seed set.

Many Dianthus species occur as common wildflowers. There has never been any evidence of hybridization between carnation and these species, nor after decades of cultivation have carnations been found in the wild. Carnation has no weedy characteristics and is not closely related to known weeds. The risk of transferring genetic traits from transgenic carnation lines to species in unmanaged environments was not judged to be significant.

Links to Further Information Expand


This record was last modified on Wednesday, February 25, 2015