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Boosting the Calcium in Potatoes
By Alfredo Flores
March 20, 2003
Germplasm stored in the Agricultural Research Service's U.S. Potato Genebank at Sturgeon Bay, Wis., may help scientists increase calcium levels in this popular vegetable.
Every year, the typical American consumes more than 140 pounds of potatoes, more than any other vegetable. So increasing calcium in the tubers could significantly boost consumers' intake of this important nutrient.
Boosting calcium would help the potatoes, too, because increased levels of calcium have been shown to reduce the severity of tuber defects such as internal brown spot and hollow heart. These internal blemishes either render potatoes unfit for sale or reduce their market value.
Geneticist John B. Bamberg, who manages the ARS Potato Genebank, has been working with Jiwan Palta, a physiologist with the Department of Horticulture at the University of Wisconsin-Madison. The two are trying to identify which of the nearly 200 wild, tuber-producing potato species are best at accumulating calcium in their tubers. While screening many potato species, the scientists found two South American species that stand out--Solanum gourlayi and S. microdontum.
When grown in low-calcium soil, S. gourlayi tubers ranked first for calcium accumulation, taking up more than double that of cultivated potato. When grown in high-calcium soil, this species ranked second, taking up three times more than cultivated potato tubers. While S. microdontum exhibited only average calcium accumulation in the control environment, it had the highest increase of any species when grown in the high-calcium soil.
Bamberg and Palta have made hybrids that will now serve as models for genetic and physiological investigations of the high-calcium trait. They will also begin to transfer genes for super-high-calcium accumulation from the wild species to the cultivar breeding pool with the help of other researchers at the ARS Vegetable Crops Research Unit in Madison.
Read more about this in the March issue of Agricultural Research magazine.
ARS is the U.S. Department of Agriculture's chief scientific research agency.