Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 15, 2008
Publication Date: December 8, 2008
Citation: Brown, C.R. 2007. Breeding for Phytonutrient Enhancement of Potato. American Journal of Potato Research. 85:298-307. DOI 10.1007/s12230-008-9028-0. Interpretive Summary: Finding the proper role of potato in the human diet is a quickly changing field of study. Potatoes are recognized as good sources of calorie-rich starches, vitamin C and potassium. But the potato is more appropriately regarded as a vegetable with phytonutrients also found in common vegetables. Potato varieties with colorful skin and flesh are options in the diet. Red and blue pigments are anthocyanins, which are potent antioxidants in the diet. Yellow to orange pigments in the flesh are xanthophylls. These pigments are needed in the human diet and potatoes with high concentrations of these compounds can be selected in breeding programs. These particular compounds are major constituents of the retina and a diet rich in them is therapeutically better to achieve optimum eye health. Potatoes are not regarded generally as particularly good sources of important minerals. However, surveys of numerous breeding lines and varieties showed a broad range of content for iron and other minerals. Iron is of particular interest, as it is deficient in half of the world’s poorest people and in developed countries is problematic due to absorption issues. A high iron content potato would be a perfect carrier because the matrix of nutrients is excellent to promote iron absorption. Understanding the genetic variation of all of these compounds will aid in the breeding of phytonutrient-rich potatoes in the future.
Technical Abstract: The potato is a vegetable that develops underground as a stem. It is a propagule in the sense that the potato itself is used as seed for the following crop. As a food it is a rich source of nutrients. Focusing on just a few categories of metabolites, it is has varying contents of carotenoids, all falling into the xanthophyll category. Of greatest interest are lutein and zeaxanthin, components of the human retina that must be obtained from foods for proper eye health. Potatoes outside the center of origin may contain from 50 to 350 micrograms per 100 g FW. Potatoes developed by farmers in the Andes, especially the Papa Amarilla class of cultivars, may contain as much as 2000 micrograms per 100 grams FW. Xanthophylls are fat soluble, have half-lives of several days, are antioxidants and associate with membranes in the cell. Anthocyanins are radically different compounds conferring red to purple coloration to skin and flesh of potato. Potatoes with color of this type range from 1.5 mg and 40 mg per 100 g FW, in colored skin but non-colored flesh types and in colored skin, solidly colored flesh types, respectively. Potent antioxidants, they are water soluble and have a half-life of several hours in the body. Some of the anthocyanins are strong anti-inflammatory agents. Potato is recognized as containing minerals, though never mentioned as a particularly rich source. A survey of advanced breeding lines and varieties at different growing locations indicates that potato has a great range of iron, manganese, zinc, potassium, calcium, and phosphorus. Iron is the most problematic mineral. Absorption from food is hindered by phytic acid and polyphenols, which are abundant in small grains and food legumes. Potato has little of these and an abundance of vitamin C which is the most important auxiliary component in food to ensure absorption of iron.