|Van Den Berg, Ronald|
Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2000
Publication Date: N/A
Citation: N/A Interpretive Summary: Mexico has about 30 wild potato species. Many of them have tremendous disease resistances of value to our commercial potato breeders. Many of these species are very similar to each other however and it is unclear how many species occur in this area. One such group of six similar species belongs to a group only known by the technical name of Solanum series Longipedicellata. We also studied species in the similar series Demissa and Tuberosa. We studied all of these species by their outer general form, using the very characters that others used to divide them into species. We found that we could recognize only three, not six species in series Longipedicellata, and that this series is extremely similar to species in series Demissa and Tuberosa. These data help document and explain the extensive taxonomic difficulty in wild potato species and add to a growing body of evidence that there are too many wild potato species recognized in current taxonomic treatments. Results will help us make predictions of clusters of disease resistance and other useful traits available to commercial potato breeders.
Technical Abstract: Species boundaries were assessed by phenetic analyses of morphological data for the wild potato (Solanum section Petota) ser. Longipedicellata : S.fendleri, S.hjertingii, S.matehualae, S.papita, S.polytrichon, and S.stoloniferum. These six tetraploid wild potato species grow in the southeastern United States (S.fendleri) and Mexico and constitute all the species of ser. Longipedicellata except for one triploid hybrid involving the diploid species S. verrucosum. We analyzed morphologically similar species in ser. Demissa (S.demissum), ser. Tuberosa (S. avilesii, S.gourlayi, S.verrucosum), and morphologically more dissimilar species in ser. Tuberosa (S.berthaultii) and ser. Yungasensia (S.chacoense). We chose S.verrucosum and S.demissum as Mexican representatives, and S.avilesii and S.gourlayi as South America representatives. The results support only three species in ser. Longipedicellata: (1) S.polytrichon, (2) S.hjertingii + S. matehualae, and (3) S.fendleri + S.papita + S.stoloniferum. Solanum avilesii, and to a lesser extent S.demissum, S.gourlayi, and S. verrucosum, are similar to members of ser. Longipedicellata, despite differences in chromosome numbers and crossability relationships. Extensive overlap of "species-specific" character states shows the difficulty of the preparation of keys, diagnosis of taxa, and cladistic analyses in sect. Petota. These data help document and explain the extensive taxonomic difficulty in sect. Petota and add to a growing body of evidence that there are too many wild potato species recognized in current taxonomic treatments.