Location: Vegetable Crops ResearchTitle: Ecogeography of Ploidy Variation in Cultivated Potato (Solanum Sect. Petota)) Author
Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/25/2010
Publication Date: 12/17/2010
Citation: Spooner, D.M., Jansky, S.H., Gavrilenko, T., Ovchinnikova, A., Krilova, E., Simon, R. 2010. Ecogeography of Ploidy Variation in Cultivated Potato (Solanum Sect. Petota). American Journal of Botany. 97(12):2049-2060. Interpretive Summary: Wild and cultivated potatoes, technically grouped in the genus Solanum, section Petota, are very similar. Their formal classification into species is difficult, and there are many conflicting publications (taxonomies) that recognize different numbers of species. In cultivated potatoes, a major taxonomic character used to recognize different species is the number of chromosomes possessed by the plant, but recent studies have shown that this is not a valid way to distinguish the species. This paper tests whether the different chromosome variants grow in different ecological habitats and in most cases they do not. In combination with other data, it gives evidence that cultivated potatoes need to be drastically classified into fewer species, with one of these species, technically known as Solanum tuberosum, having different chromosome variants. This conclusion is of importance to a wide range of scientific applications, for example, potato breeders, who will be alerted to more natural species groups to select from in their potato breeding programs.
Technical Abstract: The taxonomy of cultivated potatoes has been highly controversial, with estimates of species numbers ranging from 3-18. Ploidy level has been one of the most important taxonomic characters to recognize cultivated potato species, with diploid (2n = 2x = 24), triploid (2n = 3x = 36), tetraploid (2n = 4x = 48), and pentaploid (2n = 5x = 60) forms present. We test the environmental associations of different ploidy levels in cultivated potato species that have traditionally been recognized as Linnean taxa to see if, in combination with prior morphological, molecular, and crossing data, these ploidy variants can be recognized as distinct taxa. The Solanum tuberosum Andigenum Group (a group of Andean landraces containing diploid, triploid, and tetraploid populations recognized as distinct taxa by some taxonomic treatments) dominate the geographical coverage of the landraces, with the tetraploids most widespread, followed by its diploid and triploid cultivar-groups. Except for the S. tuberosum Chilotanum Group (tetraploids from lowland Chile), and extreme northern and southern range extensions of the Andigenum Group, it is difficult to impossible to find distinct habitats for the ploidy variants of the S. tuberosum Andigenum Group. Our distributional and ecological data, in combination with prior results from morphology, microsatellites, and crossing data, indicate that prior taxonomies recognizing many species have little to no support.