EXPRESSION OF DIHYDROFLAVONOL 4-REDUCTASE REGULATES ANTHOCYANIN BIOSYNTHESIS IN POTATO TUBER

VALIÑAS, M; LANTERI ML; BONDINO HG; SUAREZ PA; DIGILIO A; CLAUSEN A; ARJEN TEN HAVE; ANDREU AB

Mar del Plata

Congreso; XXIX Reunión Argentina de Fisiología Vegetal; 2012

BackgroundThe phenylpropanoid pathway leads to the production of phenolic acids and flavonoids,two major groups of secondary metabolites. These compounds have important roles inthe plants´ physiology but also in the prevention of various diseases such as cancerand diabetes. Chlorogenic acid from potato tubers forms a significant source ofphenolic acids in the human diet. Pigmented potato varieties also have the flavonoidsanthocyanins.ResultsWe previously studied the levels of total phenolics, anthocyanins and the antioxidantcapacity in skin and flesh of tubers of nine Andean potato varieties. We found that boththe 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 toexamine how the metabolic network is regulated, we selected four potato varietiesbased on their different metabolite profiles. We analyzed the expression of genesinvolved in the phenylpropanoid pathway via real time RT-PCR. Results show that thetranscript levels of genes responsible for chlorogenic acid synthesis were higher in skinthan in flesh. A similar result was obtained for the anthocyanin synthesis genes Stdfr(dihydroflavonol 4-reductase) and Stans (anthocyanidin synthase). Interestingly, theStans transcript was detected in non-pigmented flesh varieties. However, a negligibleexpression of Stdfr, which is responsible for the production of anthocyanin precursors,was found in these tissues.ConclusionThe results support the hypothesis that regulation of transcript levels plays an essentialrole in potato phenylpropanoid metabolism. The lack of anthocyanins in non-pigmentedflesh varieties can be explained by the lack of dihydroflavonol 4-reductase. This studyprovides information on key polyphenol biosynthetic genes, which could facilitate thedevelopment of potato varieties with enhanced health and nutritional benefits.