Antioxidant asset of resveratrol producing tomatoes by the heterologous expression of Stilbene Synthase gene

Tomato fruit contains only small amounts of flavonoids, and do not produce any stilbenes. With the aim of generating plants and fruits with increased antioxidant capacity and a wider range of potential health benefits, the tomato flavonoid route was modified through the over-expression of the grape stilbene synthase cDNA. The expression of the StS gene in tomato tissues caused the synthesis of new compounds, not present in either wild type or vector transformed plants, which were identified as trans-resveratrol and trans-resveratrol-glucopyranoside and which have a different tissue specificity, both depending on the promoter used and on the amount of precursors present in the tissues. Since the free radical scavenging capabilities of resveratrol are well known, we wanted to analyse whether its presence in tomato plants and fruit affected the level and/or the metabolism of other antioxidants normally present in tomato. The results here reported indicate that the synthesis of resveratrol affects certain metabolic routes related to primary antioxidants in different ways, according to the levels of resveratrol produced in the tissue.