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Researchers transform tomato with Petunia gene
By Bijal P. Trivedi

By adding a gene from a species of Petunia, European researchers have developed a tomato with increased levels of flavonols. These compounds occur naturally in tomatoes, albeit at very low levels, and possess antioxidant and vasodilatory properties that are thought to protect against cancer and heart disease, respectively.

The team, led by Martine Verhoeyen of Unilever Research in Bedfordshire, UK, increased the tomato's level of the enzyme chalcone isomerase (CHI), which the researchers believed created a bottleneck in flavonol production.

Verhoeyen's team modified the tomato by adding the chi gene from a species of Petunia. The gene produced high levels of the chalcone isomerase enzyme, which increased the level of flavonols up to 78-fold in the peel of the tomato. The flavonols did not appear to accumulate in the flesh of the tomato or the leaves of the plant. Levels of flavonols in these modified tomatoes were comparable to those of onions, which have naturally high flavonol levels.

In a procedure mimicking factory production of tomato paste, the researchers found that paste manufactured from the transgenic tomatoes contained a 21-fold increase in flavonols compared to unaltered tomatoes.

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Muir, S.R. et al. Overexpression of petunia chalcone isomerase in tomato results in fruit containing increased levels of flavonols. Nat Biotechnol 19, 470-474 (May 2001).

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