Are tomatoes naturally unnatural?

The news GM Tomatoes are being grown in Canada broke on the BBC late last week. They also opened a comment section which, like comments sections on any news site, is a mix of the thoughtful and bizarre.

One common reaction is that the GM tomatoes aren’t natural, and that this matters because there’s an assumption that natural is good. This might be a less popular opinion if people lived for a month with natural water supplies. More interesting is the other side of the argument, that non-GM tomatoes are natural, which makes a kind of sense, but is odd when you look closely.

The reason that tomatoes look natural is that they’re an easy enough plant to cultivate. You can grow tomatoes from seed without much trouble, and the tomato crop has seeds so it’s easy to see the cycle of life. It not stupid to think that looks natural.

We don’t see wild tomatoes in the shops and this photo from Bai and Lindhout shows why. The tomato on the right is the ‘Giant Heirloom’ tomato, grown by some farmers. The one on the left, you might need a magnifying glass to see it, is a wild tomato. At that size, it wouldn’t be so surprising to think of tomatoes as berries. Bai and Lindhout point out that developing tomato hybrids is an extremely competitive business with cultivars having a turnover of five years. It’s not just a matter of keeping up with fashions, there are other advantages like resistance to disease or longer shelf-life to breed for. This is innovation that companies want to protect so you get patents for non-GM hybrids like this one.

Bai and Lindhout’s paper ‘Domestication and Breeding of Tomatoes: What have We Gained and What Can We Gain in the Future?’ is a bit dated now, as it was written in 2007. They mention using QTLs (quantitative trait loci) and marker-assisted breeding in the future. This is now commercial practice. Bai and Lindhout also anticipated the interest in the many wild Solanum as a source of genetic diversity for tomatoes.

Tracking the origins of some species is difficult, and especially for tomato. The best archaeobotanical remains in Mesoamerica found in places that aren’t suitable for the wild crops to grow so the early domesticates appear divorced from their origins (Pickersgill 2007). To make things more complicated, most genetic diversity for tomato is found in South America, but domestication seems to have been in Mesoamerica. The domestication of crops is interesting for historical reasons, but Pickersgill notes that there are good practical reasons for studying domestication to improve modern plant breeding. Genetic studies effectively allows botanists to take plants apart to see how they work.

This intense examination of plants potentially means a future of what Vaughan, Balázs and Heslop-Harrison (2007) call ‘super-domestication’. It combines both futuristic genetic analysis and a look back to the traditional methods of farming through ethnobotany, but the reason it has promise for the future is that it acknowledges the work that earlier generations in creating unnatural varieties of crops people would want to eat.

As for the GM Tomato, not everyone will welcome it, but tomatoes have a history of vilification before acceptance. In the long term it seems it’s the fact they’re unnatural that makes tomatoes so attractive.

If you follow the links, you’ll see they all come from the same journal. In 2007 Annals of Botany published a special issue on crop domestication, which you can read with Open Access.

Image

Wild tomato and heirloom tomato by Bai and Lindhout.