Engineered plants will have more antioxidants.

It may be possible to improve the quality of tomatoes, cereals and other crops by using new genetically modified crops that contain more antioxidants, such as natural flavonoids or other phenolic compounds. These antioxidants are believed to have a protective effect against cardiovascular diseases and some forms of cancer. Consider these new crops as functional foods.

Food raw materials can be improved by using traditional breeding techniques, by genetically modifying crops or by changing the feeding practices of animals. Meat can be made more healthy by improving the fatty acid profile of animal feed. It is possible to improve the health profile of eggs by adding fish oils to the chicken feed. Rice can be given a higher content of vitamins and iron. And now tomatoes or cereals can be engineered with a high content of antioxidants, for example flavonoids, carotenoids or tocopherols (vitamin E).

Flavonoids are naturally present in most fruits and vegetables. They are as good antioxidants as the carotenoids and vitamins E or C. These antioxidants are thought to work by scavenging oxygen radicals, protecting against oxidative breakdown of biopolymers such as DNA, proteins and lipids. The breakdown of DNA molecules in cells is believed to be the most prominent mechanism for the initiation of cancer cells and for the oxidation of lipoproteins, which increases the risk of arteriosclerosis.

Plants produce an immense range of natural metabolites, many of which are of medical value. These metabolites exhibit antioxidative activities, due to the scavenging of reactive oxygen and reactive nitrogen species. They may serve as antioxidants in plants themselves, or in plant-derived components of the human diet, without being toxic or dangerous.

Major objectives of European research are to decipher the regulation of flavonoid biosynthesis, produce engineered plants tailored for the synthesis of phytoprotectants, develop molecular and biochemical tools to assist plant breeding and perform risk assessments of the engineered plants by carefully following metabolic changes in pathways not directly targeted by genetic manipulation.

To achieve these objectives, researchers will alter the expression of known genes. They will use Arabidopsis to isolate novel genes. In addition, genetic resources of different tomato accessions will be exploited by transcriptional and metabolic profiling.

The scientists are trying to identify key genes responsible for flavonoid production and have started to grow a generation of tomato plants which could potentially have high levels of flavonoids. After completing this work, the researchers will attempt to transfer their know-how to other crops, namely cereals.

Further information. Uwe Sonnewald, Institute for Plant Genetics and Crop Plant Research, Molecular Cell Biology, Corrensstrasse 3, DE-06466 Gatersleben, Germany; phone: [phone]; fax: [phone]; email: [e-mail].