Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2006
Publication Date: February 1, 2007
Citation: Bamberg, J.B. 2007. Variation for tuber acidity among potato species [abstract]. American Journal of Potato Research. 84:76. Technical Abstract: While the use of acidity by plants for defense against disease is widespread and well known (e.g., acidic fruits), little appears to be known about the range of variation in tissue acidity in potato or its implications. We collected tuber samples in sealable plastic “sandwich” bags, froze them in a household (-20C) freezer, crushed the thawed contents in the bag, then collected, centrifuged and tested the juice with a pH meter. Tuber samples of 49 populations including 24 wild and cultivated potato species were evaluated both from plants grown in screenhouse pots in Wisconsin and field plants grown on Maui, Hawaii. Significant differences were detected among populations and species. The 12 highest pH populations averaged 5.90, containing all 6 populations of cultivated species Solanum tuberosum andigena (adg), phureja, and stenotomum (stn). The 12 lowest pH populations averaged 5.62. All populations of Solanum microdontum (mcd), polytrichon, and pinnatisectum fell in this most acidic group, with all three mcd populations in the 4 most acidic ranks. The highest pH observation in pot-grown stn tubers was 6.30. The lowest population, mcd 473166, had a pH of 5.14 in Hawaii field-grown tubers (more than 14 times the H+ of the highest pH stn). Six adg populations were also grown in the field in Wisconsin and California. Population and location effects were not significant, but the effect of tissue type (skin vs flesh) was highly significant, with skin being much more acidic (whole = 5.99, Skin = 5.69, Flesh = 6.03). The speed, simplicity and economy of tissue pH screening would make it a valuable breeding and research tool if linked to resistance to pathogens, tuber quality, or other important physiological traits of potato. Investigation of such links is underway.