Fruit-specific RNAi-mediated suppression of DET1 enhances carotenoid and flavonoid content in tomatoes
Ganga Rao Davuluri, Ageeth van Tuinen, Paul D Fraser, Alessandro Manfredonia, Robert Newman, Diane Burgess, David A Brummell, Stephen R King, Joe Palys, John Uhlig, Peter M Bramley, Henk M J Pennings & Chris Bowler
Nature Biotechnology  23, 890 - 895 (2005)
Published online: 12 June 2005; | doi:10.1038/nbt1108

SUMMARY
(Source: Meridian Institute Food Security and Ag-Biotech News)

Researchers from Europe and the U.S. have developed a genetically modified (GM) tomato with heightened levels of the nutrients lycopene and beta-carotene, and also several healthful phenylpropanoid compounds, including chlorogenic acid, naringenin-chalcone, and presumed glycosides of the flavanoid quercetin. Levels of the various nutrients were increased by as much as 10 times.

In the past, several studies have reported success in using GM technology to develop tomatoes and other plants with heightened levels of one or a few of the nutrients. This is the first time, however, that researchers have been able to increase the levels of all of the compounds in one plant.

The researchers created the GM tomato by suppressing the action of a native tomato gene called DET1.

The precise mechanism by which this gene's suppression led to increased nutrient levels remains unclear. The article says, however, that the nutrients were produced through two separate metabolic pathways (the terpenoid and phenylpropanoid pathways), and there appears to be no negative effects on tomato fruit quality or overall plant growth and development. The article says that lycopene in the diet is associated with reduced rates of heart attack and is also a promising cancer chemopreventative. Beta-carotene, meanwhile, is a precursor to vitamin A -- deficiency of which is the most common dietary problem affecting children worldwide.

The United Nations Children's Fund (UNICEF) has estimated that improved vitamin A nutrition could prevent up to 2 million deaths annually among children aged between one and four years. Chlorogenic acid and quercetin are potent water-soluble antioxidants that also have health benefits.

Article abstract: http://www.nature.com/nbt/journal/v23/n7/abs/nbt1108.html