ARS | Publication request: TAXONOMY OF MEXICAN DIPLOID WILD POTATO (SOLANUM SECT. PETOTA) SPECIES: MORPHOLOGICAL AND MICROSATELLITE DATA

Submitted to: Botanical Garden Annals Missouri
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 30, 2002
Publication Date: April 15, 2005
Citation: Lara-Cabrera, S.I., Spooner, D.M. 2005. Taxonomy of Mexican diploid wild potatoes: (Solanum sect. Petota)morphological and microsatellite data. Botanical Garden Annals Missouri. 104:199-205.

Interpretive Summary: The United States, Mexico, and Central America contain about 30 wild potato species, and some of them are very useful as genetic stocks to improve the disease resistances of cultivated potatoes. Many of these species look so similar, however, that we were unsure how to identify them and if they should not be considered as fewer than 30 species. In order to try to tell them apart, we analyzed their differences with a genetic tool called microsatellites. Microsatellites are pieces of DNA (a molecule in cells that directs life processes) that change very quickly and hence showed promise to tell apart species that are very similar. However, microsatellite results group species together that are really very different, suggesting that they have reduced utility to analyze the United States, Mexican, and Central American diploid species. These results will show potato scientists not to spend effort to use them to show relationships of this group of wild potatoes.

Technical Abstract: Solanum L. section Petota Dumort., the potato and its wild relatives, contains over 200 wild species distributed from the southwestern United States to south-central Chile. Most of these species grow in the Andes, but the United States, Mexico, and Central America contain about 30 taxa of diploids, tetraploids, and hexaploids. Chloroplast DNA restriction site data show 13 of these 30 taxa to form a clade containing only diploid species, but there is low resolution within this clade. Some of these 13 taxa are similar morphologically and may not be valid species. Morphological data show extensive overlap of putative "species-specific" characters, but most species can be supported by multivariate techniques, except S. nayaritense, and S. brachistotrichum that remain problematical. Mapped nuclear microsatellite markers, developed in Solanum tuberosum, poorly distinguish species supported on morphological data, despite analyses as alleles or as unrelated characters. We sequenced some microsatellite fragments from different species. We showed many cases of divergence among priming sites, and also divergence of DNA sequences flanking the microsatellites. Our phylogenetic results, and these sequence data, suggest that microsatellites have reduced utility to analyze the United States, Mexican, and Central American diploid wild potato species.