ARS | Publication request: Survey of Tuber pH Variation in Potato (Solanum) Species

Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 22, 2009
Publication Date: April 1, 2010
Citation: Bamberg, J.B., Kiszonas, A.M. 2010. Survey of Tuber pH Variation in Potato (Solanum) Species. American Journal of Potato Research. 87(2):167-176.

Interpretive Summary: Variation in tuber pH has been previously reported in cultivated potato and shown to be associated with economic traits. We here report a broad survey of stocks in the U.S. potato genebank, including wild potato species. We discovered a wide range of pH and identified some extremely low-pH individuals in wild species. And, we found that while skin and flesh of the same tuber gave different pH readings, as did samples prepared differently (frozen, dried, cooked), rankings were consistent, so various sampling methods could be used for screening. If associated with traits like disease resistance, nutrition and tuber quality, pH testing might serve as a rapid and inexpensive screening tool in breeding programs. These improvements could impact farmers by providing cultivars that are more productive with fewer inputs. Consumers could also benefit from a more attractive and more nutritious food. The association of pH and useful traits might also provide potato scientists with clues for better understanding (and manipulating) the underlying genetic and physiological mechanisms of those traits.

Technical Abstract: Variation in tuber pH has been previously reported in cultivated potato and shown to be associated with economic traits. We here report a broad survey of potato germplasm for tuber pH, including wild Solanum species. Cultivar pH ranged about 5.5 to 6.2, while some species were as low as 5.0. S. microdontum had the lowest pH of the wild species examined. Various types of sampling were tested. Skins were generally lower than flesh, with a high correlation between the tissues. Samples that were frozen, cooked, or reconstituted from dried powder had different absolute pH values, but these were highly correlated, so germplasm would be ranked for pH similarly regardless of method. If associated with traits like disease resistance, nutrition and tuber quality, pH testing might serve as a rapid and inexpensive screening tool in breeding programs. The association of pH and useful traits might also provide clues for exploring underlying genetic and physiological mechanisms in potatoes.