Editing Flavr Savr (section)

== Characteristics ==
Tomatoes have a short shelf-life in which they remain firm and [[Ripening|ripe]]. This lifetime may be shorter than the time needed for them to reach market when shipped from winter growing areas to markets in the north, and the softening process can also lead to more of the fruit being damaged during transit. If picked while ripe, tomatoes can spoil before reaching far-away consumers due to their short lifetime. To address this, tomatoes intended for shipping are often picked while they are unripe, or "green", and then prompted to ripen just before delivery through the use of [[ethylene]] gas, which acts as a [[plant hormone]]. The downside to this approach is that the tomato does not complete its natural growing process, and the final flavor suffers as a result.<ref>{{Cite web|url=https://gizmodo.com/the-original-genetically-modified-tomato-youll-never-ea-559924439|title=The Original Genetically Modified Tomato You'll Never Eat Again|website=Gizmodo|date=24 June 2013 }}</ref>

Through genetic engineering, Calgene hoped to slow down the ripening process of the tomato, thus preventing it from softening too early, while still allowing the tomato to retain its natural color and flavor. This would allow it to fully ripen on the [[vine]] and still be shipped long distances without it going soft.<ref name="fray" /> Calgene scientists used the modified bacterial parasite ''[[Agrobacterium tumefaciens]]'' to transfer genetic material into Flavr Savr plant cells. The bacterium normally "infects" plants  with foreign genes as a part of its lifecycle. The harmful, parasitic genetic material was removed from the bacterial T-plasmid and was replaced by the favored genes.<ref name=":0" /> 

The Flavr Savr was made more resistant to [[Decomposition|rotting]] by the addition of an [[antisense]] [[gene]] which interferes with the production of the [[enzyme]] [[Polygalacturonase|beta polygalacturonase]]. The enzyme normally contributes to spoilage by degrading [[pectin]] in [[plant cell wall|cell wall]]s and results in the softening of fruit, which makes them more susceptible to being damaged by [[fungal]] infections and physical actions.

Flavr Savr turned out to disappoint researchers in that respect, as the antisense version of the PG gene had a positive effect on shelf life, but not on the fruit's firmness. The Flavr Savr was too soft to be reliably machine-picked and transported when harvested while ripe, so the tomatoes still had to be harvested like any other unmodified vine-ripe tomato.<ref>Martineau, Belinda. 2001. ''First Fruit: The Creation of the Flavr Savr Tomato and the Birth of Biotech Food''. McGraw-Hill.</ref> An improved flavor, later achieved through traditional breeding of Flavr Savr and better-tasting varieties, would contribute to selling Flavr Savr at a premium price at the supermarket.

The Flavr Savr also contained a kanamycin-resistance gene. This gene gave bacterial cells and [[Chloroplast|chloroplasts]] resistance to multiple antibiotics, including kanamycin. The kanamycin-resistance gene was used during the tomato's creation phase to help scientists identify plants with the genes successfully added. Kanamycin is toxic to chloroplasts and is deadly for some plants. When researchers exposed tomato plants to high levels of kanamycin, only plants with the added genes survived.<ref>{{Cite web |last=Miller |first=Susan |date=May 27, 1994 |title=Genetic first upsets food lobby |url=https://www.newscientist.com/article/mg14219270-700-genetic-first-upsets-food-lobby/ |access-date=February 17, 2022 |website=New Scientist}}</ref>