Tomatoes provide an excellent target for genetic enhancement to raise levels of flavonoid anti-oxidants. Flavanoids (including anthocyanins) are a good source of water-soluble anti-oxidants, while the main anti-oxidant in ordinary tomatoes is lycopene – a fat-soluble molecule. There is evidence that best protection against disease is achieved when both types of anti-oxidants are present in the diet.
Other attempts have been made to increase anthocyanins levels in tomatoes – using both GM and more traditional methods. However successes have been limited to increasing levels in the peel of the tomato, which represents a very small proportion of the tomato’s weight. Some of these purple-skinned tomatoes are available on the market, but the levels of anthocyanins present are significantly lower than in NPS purple-fleshed fruit.
To achieve the desired levels of anthocyanins, we used genes from 2 plants.
Delila (Del) and Rosea1 (Ros1) genes produce the transcription factors which combine to produce anthocyanins in snapdragon (antirrhinum) flowers.
The MYB12 gene from arabidopsis thaliana is a flavonol-specific activator of flavonoid biosynthesis.
Vectors were introduced using the fruit-specific E8 promoter.
Tomatoes shown are wild type (red); containing Del/Ros1 only (orange); containing MYB12 only (purple); and with all three genes (dark indigo).