| No anti-GMO literature would be complete without mentioning— or even better, illustrating— the"fishberry," the monstrous half-strawberry, half-fish. Even scientists and media sources frequently refer to tomatoes or strawberries with fish genes. But do fruits with fish genes really exist? |  The Nonexistent "Fishberry" (artist's rendition) |
Short answer: no.
The story about tomatoes with fish genes does have its genesis in fact. In 1991, researchers at DNA Plant Technology developed an experimental genetically engineered variety of tomato that expressed a gene identified in an Arctic flounder (1). The flounder gene encoded a protein which confers cold resistance to the fish. The goal was to develop tomato plants that could withstand frost in the field and fruits that resist cold damage in storage. This particular experiment however was a failure and did not produce frost resistant plants.
Despite the failure, the story continues to circulate as if the experiment worked, or worse, as if the fish-gene tomato might exist or has ever existed in the marketplace. That a current BBC special feature on genetic engineering uses the failed "tomato with fish genes" experiment to illustrate successful genetic engineering is particularly ironic. After explaining the steps of the process, the website concludes cheerily:
"This GM tomato plant contains a copy of the flounder antifreeze gene in every one of its cells. The plant is tested to see if the fish gene still works. Is it frost resistant? Yes it is."
Actually, as it turns out, no it is not.
The existence of "antifreeze proteins" (AFPs) has been known since the late 60s (2), and have since been identified in many organisms that have evolved resistance to freezing temperatures, including bacteria, fungi, fish, insects, and plants (3). AFPs— technically called thermal hysteresis proteins— prevent freezing damage to cellular structures by slowing or stopping the formation of ice crystals inside a cell. Since the 1991 failure, researchers have continued experimenting with various antifreeze genes in an attempt to improve frost resistance in plants, but with very limited success (4). Recent experiments using an AFP identified in carrots have shown some modest success (5). Could there be "tomatoes with fish genes" in the future? Maybe. But given the apparent "yuck factor" perception, it is doubtful that such a product would be marketable without a major change in public opinion.One key point that most retellings of the story miss is that the gene used in the experiments is not actually a "fish gene" in the sense that most people imagine. Although the genetic code is the universal language of life that all organisms on earth understand, there are "regional dialects." The genetic vocabulary used by plants is slightly different than that used by animals and other organisms— technically referred to as "codon bias." Although a plant nucleus is capable of understanding an animal gene, the process works better if the gene uses a vocabulary more similar to the one a plant normally uses. For this reason, the researchers who developed the "fish-gene tomato" did not physically move a gene from an Arctic flounder into a tomato; instead, they created a synthetic gene from scratch based upon the genetic sequence of the flounder gene, but which had been translated into plant dialect to optimize its expression in the tomato. Thus, the gene did not physically "come from a fish;" more precisely, only information was taken from a fish.
