Submitted to: Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/15/2004
Publication Date: 3/15/2005
Citation: Spooner, D.M., Flor, R., Nunez, J., Ghislain, M., Naik, P.S. 2005. Cultivar nuclear and chloroplast DNA reassessment of the origin of Indian potato varieties and its implications for the origin of the early European potato. Theoretical and Applied Genetics. 110:1020-1026. Interpretive Summary: The modern cultivated potato was first recorded in Europe in 1562, but no one knows exactly where it came from. Two competing ideas is that it came from the Andes Mountains of South America somewhere between Venezuela and Argentina, and another idea is that it came from near sea level areas in Chile. Potatoes from these two areas are different in a number of ways including how they can be used in breeding programs (how they can be used to make hybrids), how they look, and how they produce potatoes under different conditions of light availability. These are all important factors because they relate to the use of potatoes from these areas for modern breeding programs. This study reexamines these competing ideas through a reexamination of the DNA of potatoes from India that are thought to be old remnant populations from the first introductions of potato to Europe. These results fail to support the currently held idea that the earliest potatoes came from the Andes Mountains, and suggest that the first European potatoes came from Chile. It forces us to reexamine long-held ideas about the original home of cultivated potato.
Technical Abstract: The modern cultivated potato was first recorded in Europe in 1562, but its area(s) of exportation has long been in dispute. Two competing hypotheses have proposed an 'Andean' area (somewhere from upland Venezuela to northern Argentina) or a lowland south central 'Chilean' area. Potato landraces from these two areas can be distinguished, although sometimes with difficulty, by 1) cytoplasmic sterility factors, 2) morphological traits, 3) day length adaptation, 4) microsatellite markers, and 5) co-evolved chloroplast and mitochondria DNA. The Chilean introduction hypothesis originally was proposed because of similarities of Chilean landraces to modern 'European' cultivars regarding traits 2 and 3. Alternatively, the Andean introduction hypothesis suggested that 1) traits 2 and 3 of European potato evolved rapidly, in parallel, from Andean landraces through selection after import to Europe, and 2) the worldwide late blight epidemics beginning in 1845 in the United Kingdom displaced most existing European cultivars and the potato was subsequently improved by importations of Chilean landraces. We reassess these two competing hypotheses with nuclear microsatellite and chloroplast DNA analyses of 1) 32 Indian cultivars, some of which are thought to preserve putatively remnant populations of Andean landraces, 2) 12 Andean landraces, and 3) five Chilean landraces. Our microsatellite results cluster all Indian cultivars, including putatively remnant Andean landrace populations, with Chilean landraces, none with the 'old Andigenum' type as expected with the Andean landraces. Some of these Indian landraces, however, lack the chloroplast DNA typical of Chilean landraces and advanced cultivars and likely are hybrids of Andean landraces with Chilean clones or more advanced cultivars. These results lead us to reexamine the hypothesis that early introductions of potato to Europe were solely from the Andes.