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The tomato was made more resistant to rotting, by adding an antisense gene which interferes with the production of the enzyme polygalacturonase (see RNA interference). This enzyme is normally responsible for cell walls softening during the fruit ripening.
Unmodified tomatoes are picked before fully ripened and artificially ripened using ethylene gas which acts as a plant hormone. Picking the fruit while unripe allows for easier handling and extended shelf-life. Flavr Savr tomatoes could be allowed to ripen on the vine, without compromising their shelf-life. The intended effect was an improved flavor which would warrant a premium price at the supermarket.
The FDA stated that special labeling for these modified tomatoes was not necessary because they have the essential characteristics of non-modified tomatoes. Specifically, there was no evidence for health risks, and the nutritional content was unchanged.
The failure of the Flavr Savr has been attributed to Calgene's inexperience in the business of growing and shipping tomatoes . The variety of tomato Calgene started with was considered by farmers to be inferior, and insufficient resources were allocated to traditional plant breeding. As a result, Calgene's fields produced only 25-50% as many boxes per acre compared to most growers. Of these, only half as many as anticipated were large enough to be sold as premium-priced. Furthermore, much of the initial harvest was damaged during processing and shipping because ripe tomatoes are unavoidably more delicate than unripened ones. Equipment designed for handling peaches was purchased, and specialized shipping crates were developed, both at great expense. These costs along with competition from a new conventionally bred Long Shelf Life (LSL) variety prevented the Flavr Savr from becoming profitable, and Calgene was eventually bought by Monsanto which was primarily interested in Calgene's ventures into cotton and oilseed.
In UK, Zeneca also produced a tomato paste made from GM tomato that is similar to but often confused with Flavr Savr. The higher pulp content of this GM tomato enables more efficient processing of the thick pastes and ketchups preferred by consumers. The paste was labeled as "genetically altered", and priced (at a loss) below its competitors. This commercialization strategy was primarily intended as a marketing experiment which proved that, at the time, European consumers would accept genetically engineered foods. This attitude was drastically changed after outbreaks of Mad cow disease weakened consumer trust in government regulators, and protesters rallied against the introduction of Monsanto's Roundup-Ready soybeans. (see Trade war over genetically modified food)
Addition of an "antibiotic resistance" gene
The Flavr Savr also raised some general safety concerns because of a secondary genetic modification. In order to make it easier to identify plants with the modified gene, the "delayed ripening" modification was supplemented with a genetic marker, and in this case their chosen marker was a gene segment that confers resistance to a particular antibiotic, kanamycin. A laboratory demonstration showed that the bacteria can sometimes uptake and incorporate plasmids of genetic material from rotting vegetation suggested the possibility that if Flavr Savr was farmed commercially, it might encourage the emergence of new bacterial strains in the environment resistant to kanamycin. This result did not seem to be known to the experts who advised the FDA.
Although kanamycin is not a major antibiotic, there have been concerns that having a genetic resistance to one antibiotic may make it easier for bacteria to evolve resistance to other related antibiotics in the same "family", and since different types of bacteria can sometimes exchange genetic material, this raised questions as to whether it was proper to embed genes into a plant strain for convenience that could conceivably have a negative future impact on public health. Even if the risk of encouraging new super-strains of antibiotic-resistant bacteria was considered negligible, the idea that a company would choose to implant these particular genes into bulk crops, when those genes gave no special advantage either to the product or to the end consumer, raised doubts in some people's minds as to whether the industry was behaving responsibly.
These concerns over antibiotic resistance genes were not generally about the safety of eating the resulting tomatoes, but about more general risks associated with the wide scale cultivation of material carrying these genes, and the perception that this gave of the industry's attitude to public safety.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Flavr_Savr". A list of authors is available in Wikipedia.|