A news report on a new study says that the same genetic mutation that gave modern supermarket tomatoes their luscious-looking uniform red color is also the one that reduced its sweetness.
It may be possible to use this new information to genetically engineer a new breed of tomatoes that are both sweeter and uniformly red but there is resistance to doing so, and so the best bet for those who want sweet tomatoes is to grow so-called heirloom tomatoes that date to before the appearance of the mutation that gave rise to uniform ripening.
The tomato study was published in Science (vol. 336 no. 6089 pp. 1711-1715, 29 June 2012)