Carotenoid content and color in diploid potatoes

The yellow pigment in potato (Solanum L. sp.) tuber flesh is caused by various carotenoids that may protect against cancer, cardiovascular disease, and macular eye degeneration. The objectives of this research were to 1) identify and quantify the carotenoids present in I I diploid clones from a hybrid population of Solanum phureja ssp. phureja Juz. & Bukasov-S. stenotomum ssp. stenotomum Juz. & Bukasov and two tetraploid potato cultivars (the yellow-fleshed 'Yukon Gold' and the white-fleshed 'Superior'), and 2) determine the relationship between tuber yellow intensity and carotenoid content. Yellow intensity was measured by a colorimeter programmed to calculate a yellowness index, YI E-313. Carotenoid analyses were performed on an automated high-performance liquid chromatography system with software for integration and quantitation with detection at 450 urn using a diode array detector. Six major carotenoids were detected: neoxanthin, violaxanthin, lutein-5,6-epoxide, lutein, zeaxanthin, and an unknown carotenoid. Total carotenoid content in the yellow-fleshed diploid clones was 3 to 13 times higher than 'Yukon Gold' and 4 to 22 times higher than 'Superior'. Both total and individual carotenoid contents were positively correlated with tuber yellow intensity. There was an exponential relationship between total carotenoid content and tuber yellow intensity. This suggests that selecting for more intense yellow flesh will result in higher levels of carotenoids. These specific diploid clones were selected for this study because they produced at least five percent 2n pollen; they have the potential to make significant contributions to improving the nutritional status of tetraploid potatoes through 4x-2x hybridizations.