ARS | Publication request: Potato Phytonutrient Analysis and Engineering

Submitted to: Phytochemical Society of North America Meeting and Newsletter
Publication Type: Abstract Only
Publication Acceptance Date: May 15, 2008
Publication Date: N/A

Technical Abstract: Potatoes have the highest per capita consumption of any vegetable, a fact which emphasizes their potential to be a key dietary source of health-promoting compounds. Only a fraction of the genetic diversity available in potato wild-species has been incorporated into modern cultivars. LCMS analysis of methanolic extracts from diverse potato germplasm was used to better understand the extent of qualitative and quantitative phytonutrient variation among potatoes. Glycoalkaloids (GAs) were one major source of diversity and ~100 different GAs were found in LCMS analysis of tuber extracts from only 7 genotypes, substantially more than expected based on the literature. Other compounds in which substantial variation was found included phenolic acids, flavonols and polyamines. Extracts from some genotypes were found to have anticancer properties when assayed against LNCaP (androgen-dependent) and PC-3 (androgen-independent) prostate cancer cells. Genotypes with total phenolic content exceeding 10 mg/g DW were identified. Chlorogenic acid (CGA) is the most abundant tuber phenolic, has numerous health-promoting properties and can comprise over 90% of a tuber’s total phenolic content. RNAi is being used to explore the effect on tuber phenolic content of silencing hydroxycinnamoyl CoA quinate hydroxycinnamoyl transferase, which synthesizes CGA. Phytonutrient concentration was found to vary during tuber development, with younger tubers having greater concentrations of many compounds, including CGA. The folate content of over 70 genotypes was examined and about a 3-fold range found. Overexpression of two genes involved in folate synthesis is being used in an attempt to increase folate in potatoes.