Thursday, March 10, 2016








On Thursday last week I mentioned a GM tomato. Having looked it up again, I remembered that it was called the Flavr Savr tomato. What reminded me of it was the discussion of ethylene- a substance that plants create to induce the ripening of the fruit, and that we often spray on fruits like tomatoes so that we are able to pick them while green and then ripen them. The Flavr Savr was invented to get rid of the need to pick tomatoes green and spray them with ethylene. What they did was alter the gene (to my understanding they simply flipped a gene sequence around) to reduce the amount of polygalacturonase produced by the tomato. This is an enzyme that breaks down the pectin in cell walls and contributes to fruit softening. The result was a vine-ripened tomato that stayed significantly firmer than ordinary tomatoes.
Source: Bruening, G., and J. M. Lyons. The Case of the FLAVR SAVR Tomato. Rep. California Agriculture Online, n.d. Web. <http://californiaagriculture.ucanr.org/landingpage.cfm?article=ca.v054n04p6>.
Research to control the ripening of tomatoes continues. At UC Berkeley, Athanasios Theologis and colleagues have identified and blocked a gene responsible for ripening. Fruit of this tomato and of similarly modified crops are ripened “on command” by treating on the vine with ethylene, giving freshness, improved flavor and reduced spoilage.

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