Submitted to: Plant Systematics and Evolution
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/17/2007
Publication Date: 9/22/2007
Citation: Ames, M., Salas, A., Spooner, D.M. 2007. The discovery and taxonomic implications of a novel 41bp chloroplast DNA deletion in wild potatoes. Plant Systematics and Evolution. 268:159-175. Interpretive Summary: The common potato of world commerce, Solanum tuberosum, has a rich genepool of about 190 wild and cultivated species that are of great importance to potato breeders because they can be used as breeding stock to improve the tastes, productivity, or disease resistance of the cultivated potato. There is great disagreement among taxonomists about the validity of these 190 species, and about their relationship to the cultivated species Solanum tuberosum. This study assesses the presence of a DNA marker that helps show the origin of the cultivated species in 38 wild species that have never been examined for its presence before. While it does not discover the marker, it discovers a new one in three of these 38 species. In combination with an examination of the overall form (morphology) of these three species, we highlight their possible relationships not imagined before by other scientists.
Technical Abstract: A 241-bp chloroplast deletion in the intergenic region flanking the 3'end of the trnV-UAC gene has been shown to have major phylogenetic importance in determining the origin of the cultivated potato, as it characterizes most landrace populations from lowland Chile and putative wild species in Bolivia and Argentina, but not landraces from the Andes from Venezuela to northern Argentina. We screened 199 accessions of 38 wild potato species in eight of the 19 tuber-bearing (Solanum section Petota) series that have not been examined before for this deletion as part of a comprehensive taxonomic reevaluation of section Petota. A novel (41 bp) deletion was discovered in this region for 30 accessions of three species: S. chiquidenum (5 of 10 accessions), S. chomatophilum (18 of 28), and S. jalcae (6 of 6), but no 241-bp deletion was found. Current phylogenetic interpretations have never suggested these three species to be related. This deletion, and accessions without the deletion, is found throughout the north-south range of all three species in northern and central Peru, but not east of the Marañón River. Multivariate morphological analyses of these 44 accessions showed no morphological associations to the deletion. Solanum chomatophilum and S. jalcae are so similar as to possibly be conspecific, but S. chiquidenum is clearly distinctive.