The purple tomato was created by Cathie Martin at the John Innes Centre in the UK. In 2008, her team reported that mice whose diet was supplemented with purple tomato powder lived nearly 30 per cent longer than those on a standard diet or a diet supplemented with powder from normal tomatoes.
“A 30 per cent longer lifespan is incredible,” she said during the presentation, though of course the results of animal studies don’t necessarily apply to people.
There are already tomato varieties with purple skins, but the genetically modified purple tomatoes have purple flesh as well. They contain around 10 times more anthocyanins, which are antioxidant pigments.
To achieve this, Martin added two genes from snapdragon (Antirrhinum) plants and one from thale cress (Arabidopsis). The added genes are active only in the fruits, where they boost the activity of the plants’ existing machinery for making anthocyanins.
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“We aim to market these tomatoes as nutritionally enhanced, but not with any specific health claims,” said Nathan Pumplin at Norfolk Plant Sciences during the presentation.
The higher level of anthocyanins also doubles the shelf life of the tomatoes. That means the purple tomatoes should be more environmentally friendly than comparable varieties.
