Submitted to: American Journal of Botany
Publication Type: Abstract Only
Publication Acceptance Date: 4/27/2007
Publication Date: 6/14/2008
Citation: Ames, M., Spooner, D.M. 2008. DNA from herbarium specimens settles a controversy about origins of the European potato [abstract]. American Journal of Botany. 95(2):252-257. Interpretive Summary:
Technical Abstract: Landrace cultivars of potato, Solanum tuberosum, are widely distributed in the mid to high elevations of the Andes from Venezuela south to northern Argentina, and then with a break in distribution in the lowlands of central Chile in Chiloé Island and the Chonos Archipelago immediately to the south. Although these two population groups are morphologically very similar, but have been distinguished by minor leaf differences, a 241-bp plastid deletion in the intergenic region flanking the 3'end of the trnV-UAC gene in Chilean (but not Andean) cultivars, and day-length adaptation with the Chilean cultivars better adapted to tuberization in high and low latitudes. Cultivated potatoes were first documented outside of South America 1562 in the Canary Islands, Spain, and then rapidly diffused worldwide as a major food crop. There are three hypotheses about the Andean vs. Chilean source of these early European introduction. The first hypothesis considers that the European cultivars were introductions of Chilean landraces, the second of Andean landraces, and the third proposed multiple introductions from both areas but with early selection of the Chilean landraces because of better day-length adaptation to higher latitudes. We obtained data for the presence or absence of the 241-bp plastid deletion in 40 pre-1900 herbarium specimens, 19 of these collected before 1850, a date when the Irish potato famine fungus late blight was believed to wipe out the Andean cultivars to later be replaced by Chilean ones. We document both Andean plastid type first in 1700 and in 10 samples before 1850; and Chilean plastid type first in 1829 and in nine samples before 1850. The data support first introductions of Andean potatoes, but the adoption of Chilean germplasm before 1850.