Tuesday, April 21, 2015

Transgenic Sweet-Potatoes

One of the first tools available to biologists seeking to make transgenic plants was a natural bacteria called Agrobacterium. The bacteria infects plants and induces the production of auxins and cytokinins, plant hormones that together trigger the growth of a disordered plant tissue called a gall. The gall provides nutrients that the bacteria then uses for its own growth. The bacteria pulls off this trick by inserting genetic information into plant cells. It can do this because it carries a plasmid that can function both in its own cells and in the cells of a plant. When the bacteria infects the plant, the plasmid is transferred into the plant's cells. Once there, the plasmid integrates into the genome of the plant and activates. The bacteria are natural genetic engineers.

Genetic remnants can be left behind whenever the bacteria does this trick and nowadays we can do genome sequencing to find such remnants. Kyndt et al found remnants of this process in sweet-potatoes (Ipomea batatas). In particular, they found such a fragment inserted into an intron of an F-box gene in the sweet-potato genome. Interestingly, this interruption is found in all domesticated sweet-potatoes they examined and not in wild related species.

The insertion contains multiple complete genes and results in the interruption of the F-box gene. F-box genes are generally involved in protein degradation and in plants they're involved in the regulation of development during growth. It isn't clear that the insertion they found results in a change in the development of the plant associated with domestication, however. They are still working on this.

Oh yes, did I mention they found this fragment in all samples they examined of domesticated sweet-potatoes? This means that every single sweet-potato is a transgenic organism, a GMO. We didn't make it a GMO, but there is no way around it, every sweet-potato is a GMO.

Every sweet-potato is a GMO.

Are you against GMOs? Then don't eat any more sweet-potatoes. Are you actually against the business practices of Monsanto surrounding their GMO and herbicide products? Then rail against those business practices instead of the red herring that GMOs are in the overall story.

  1. Agrobacterium: en.wikipedia.org/wiki/Agrobacterium
  2. Kyndt et al, 2015: m.pnas.org/content/early/2015/04/14/1419685112.full.pdf
  3. F-box genes: en.wikipedia.org/wiki/F-box_protein
  4. Red herring: en.wikipedia.org/wiki/Red_herring