CONICET | Buscador de Institutos y Recursos Humanos

Background The phenylpropanoid pathway leads to the production of phenolic acids and flavonoids, two major groups of secondary metabolites. These compounds have important roles in the plants´ physiology but also in the prevention of various diseases such as cancer and diabetes. Chlorogenic acid from potato tubers forms a significant source of phenolic acids in the human diet. Pigmented potato varieties also have the flavonoids anthocyanins. Results We previously studied the levels of total phenolics, anthocyanins and the antioxidant capacity in skin and flesh of tubers of nine Andean potato varieties. We found that both the phenolic acid content and the antioxidant capacity were higher in skin than in flesh. As expected, anthocyanins were only detected in pigmented tissues. In order to examine how the metabolic network is regulated, we selected four potato varieties based on their different metabolite profiles. We analyzed the expression of genes involved in the phenylpropanoid pathway via real time RT-PCR. Results show that the transcript levels of genes responsible for chlorogenic acid synthesis were higher in skin than in flesh. A similar result was obtained for the anthocyanin synthesis genes Stdfr (dihydroflavonol 4-reductase) and Stans (anthocyanidin synthase). Interestingly, the Stans transcript was detected in non-pigmented flesh varieties. However, a negligible expression of Stdfr, which is responsible for the production of anthocyanin precursors, was found in these tissues. Conclusion The results support the hypothesis that regulation of transcript levels plays an essential role in potato phenylpropanoid metabolism. The lack of anthocyanins in non-pigmented flesh varieties can be explained by the lack of dihydroflavonol 4-reductase. This study provides information on key polyphenol biosynthetic genes, which could facilitate the development of potato varieties with enhanced health and nutritional benefits.