Database Product Description
- Host Organism
- Dianthus caryophyllus (Carnation)
- Increased shelf-life due to reduced ethylene accumulation through introduction of truncated aminocyclopropane cyclase (ACC) synthase gene; 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
Summary of Introduced Genetic Elements Expand
Characteristics of Dianthus caryophyllus (Carnation) Expand
Modification Method Expand
Characteristics of the Modification Expand
Environmental Safety Considerations Expand
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.
Carnations are sold to consumers as cut flowers, but are also sold as cuttings or plants. Flowers are cut with great care to ensure that the consumer receives a flower that will last as long as possible. However, once a flower has been cut, it starts to deteriorate and is susceptible to premature inrolling (wilting) of the petals. The deterioration is a serious problem for carnations and is caused by the plants own production of ethylene, a natural plant hormone that triggers the aging process and leads to petal wilting. To ensure that the flowers have an acceptable vase-life, growers chemically treat all carnations with a solution of silver thiosulfate (STS) or other chemicals such as amino-oxyacetic acid (AOA). These chemicals can double the usual vase-life by reducing the plant's sensitivity to ethylene and thereby slowing down wilting and subsequent plant death. The most widely used of these chemicals, STS, is a polluting metal salt and is both toxic and a skin irritant.
The enzyme 1-aminocyclopropane-1-carboxyllic acid (ACC) synthase, normally found in carnations, is responsible for the conversion of s-adenosylmethionine to ACC, which is the immediate precursor of ethylene. The transgenic carnation line 66 was developed using recombinant DNA techniques to display suppressed ACC synthase activity, and thus reduced ethylene synthesis and therefore longer vase life, by inserting an additional truncated copy of the ACC synthase encoding gene. The presence of the truncated ACC synthase gene suppresses the normal expression of the native ACC synthase gene, and while not completely understood, the mechanism of “downregulation” is likely linked to the coordinate suppression of transcription of both the endogenous gene and the introduced truncated ACC synthase gene.
Carnation line 66 was field tested in the United States, United Kingdom, the Netherlands, and Australia. Results demonstrated that genetically modified carnations had a vase life in water of 22 days, without requiring chemical treatment with STS or AOA. In the same study, non-genetically modified carnations only had a vase life in water of 10 days, and required treatment with STS or AOA to guarantee a vase life in water of at least 8 days.
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 in Canada and the United States. 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 line 66 to species in unmanaged environments was insignificant.
Links to Further Information Expand
This record was last modified on Wednesday, February 17, 2016