The tomato is perhaps rivalled only by the fire engine for its iconic redness. Carotenoids are the chemical dyes responsible, but different dyes called betalains colour many other plants, fruit and vegetables. The luscious red tomato appears on the left here, unripe at the top and ripe beneath. Scientists genetically engineered another tomato to produce a type of betalain called betacyanin, giving it a deep purple colour (2nd from left). Similar treatment with a yellowish dye (betaxanthin) produced the tommy on the middle right. But this is not just about livening up salads – each of these chemicals has potential health benefits, from antioxidant to anti-inflammatory properties – and the tomato on the right contains all of them. In the future, tomatoes and other plants might act as sources for healthy betalains, which may also make the plants themselves more resistant to diseases.
Written by John Ankers
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.