ARS | Publication request: Species limits of Solanum berthaultii Hawkes and S. tarijense the implications for species boundaries in Solanum sect. Petota

Submitted to: Taxon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 2007
Publication Date: November 10, 2007
Citation: Spooner, D.M., Fajardo, D., Bryan, G. 2007. Species limits of Solanum berthaultii Hawkes and S. tarijense the implications for species boundaries in Solanum sect. Petota. Taxon. 56:987-999.

Interpretive Summary: There are about 200 species of wild potatoes widely distributed throughout the Americas from the southwestern United States south to Argentina, Chile, and Uruguay. Many of these species are very similar to each other and they may not all be worthy of recognition as valid species. This study uses characters of the DNA of two of these wild species growing in Bolivia and Argentina, technically known as Solanum berthaultii and S. tarijense. Their DNA traits, in combination with prior results on their overall form (morphological traits) lead us to combine these two species into a single species. We show how the pattern shown in these two species is present in other wild potatoes and suggest that if this trend continues how there will be a greatly reduced number of wild potatoes recognized in the future. Because species names are used to make inferences on their use, as in potato breeding programs, this study helps us to make better inferences about the useful traits of this species.

Technical Abstract: Solanum berthaultii and S. tarijense are two wild potato (sect. Petota) species distributed in Bolivia to northern Argentina. All authors have accepted them as good species since their publication in 1944, but they have been hypothesized to hybridize extensively with each other and with other species, despite their classification into different series and superseries by some authors. This study is a molecular counterpart (AFLPs and chloroplast DNA restriction site data and the survey of a chloroplast DNA deletion) to a prior morphological study of these two species. AFLP data show weak support for separate species status for some accessions, but with many exceptions. In agreement with the morphological results, we place both into synonymy as S. berthaultii, and use herbarium specimen data for a taxonomic treatment to include a description, synonymy, and mapping of all accessions. We show similar taxonomic problems in sect. Petota, and suggest that there will be a continuing trend of species reductions in wild potatoes.