Your Tomatoes Are Flavorless, Right? Here's Why
Don't you just lurv science?There are two pieces of late-breaking news on the tomato beat this week. First of all, tomatoes have shoulders. Second, tomatoes taste lousy. If you're younger than 70, you probably already know about the lousy part. The shoulders are surely more of a surprise — but they're both key parts of a new study published in Science that explains what's going on in the sorry world of supermarket tomatoes, and why they taste nothing like their sweet, flavorful cousins in the wild.
It was a good 70 years ago that marketers first started catching wise to something farmers knew already: a tomato on the vine that's uniformly light green may hardly be ready for eating, but it's exactly ready for picking — at least if it's destined for somewhere far away. By the time it's packed, shipped, unloaded at the store and displayed on the shelves, it will have turned a perfect, even red, which is eye-candy to shoppers.
Not all tomatoes send so clear a pick-me signal when they're ripening on the vine. Some have a more uneven look, with patches of darker green, particularly on the shoulders — the raised area at the top of the fruit that circles the depression where the stem attaches. Some of these might be ready for picking too — but some might not be, leading to a mixed shipment arriving at the store, half of which gets left on the shelves. So for that same seven decades, plant breeders have been selecting seeds from the uniformly green tomatoes, crossing them with other uniformly green ones and producing an uber-race of perfect visual specimens. But as with other very pretty things — the sea anemone, wolfbane, John Edwards — looks can mislead.
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Sifting through the tomato genome wasn't even possible until the entire thing was sequenced in the first place — something that happened just last summer and was announced in the journal Nature. With that sequence in their hip pockets, Powell and her colleagues collected some wild tomatoes with dark green shoulders and crossed them with their prettified, citified cousins. This allowed them to compare the similarities and differences between the two and eventually narrow the search for the culpable gene down to chromosome number 10. Studying that single chromosome more closely, they found a gene called SIGLK2, a sort of genetic master switch that regulates whether other genes are activated or remain inactive.
The genes that SIGLK2 controls regulate the formation of chloroplasts, components of cells that control photosynthesis. A heavy concentration of chloroplasts in a tomato leads to a heavy shading of green — which is precisely the quality plant breeders look to avoid. The problem is, chloroplasts also increase sugar levels in the tomato, and sugars play a key role in creating flavor.
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Read more:
http://www.time.com/time/health/article/0,8599,2118455,00.html#ixzz1zTXNeA83The conclusion?
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One string of bases in the flavorless tomatoes is made up of a series of seven A's. In wild, tastier tomatoes there are only six. The proof that that infinitesimal flaw is the mutation responsible for poor taste came when Powell's team inserted a gene with the shorter sequence into a supermarket variety tomato genome and the sugars in the resulting fruit jumped 40%.
See what happens when we humans mess with Mother Nature?