|Castillo, Raul - UNIVERSITY OF WISCONSIN|
Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 6, 1996
Publication Date: N/A
Interpretive Summary: There are over 200 species of wild potatoes of extreme importance in breeding programs to improve our commercial potato crop. The taxonomic grouping of these wild potatoes into related species is useful to understand how to better use them in these breeding programs. There are many disagreements among taxonomists how these species are best grouped, and the relationships of the species is poorly understood. This study examines relationships of wild potatoes with the genetic material called DNA, present in the chloroplasts (organellels containing chlorophyll) of these species. The results show four groups of species, far fewer than the 19 groups thought to occur by the most recent taxonomist grouping wild potatoes. This genetic technique using DNA from chloroplasts is very useful to investigate questions of relationships in wild potatoes, but has potential problems because of the way this DNA is contributed only from the mother plant, not the father plant. Ultimately, therefore, these results must be compared to other studies using DNA contributed from both the mother and the father plants.
Technical Abstract: Chloroplast DNA restriction enzyme site analysis was used to test hypotheses of series and superseries affiliations of 76 taxa, representing 11 of the 13 South American series of wild potatoes (Solanum sect. Petota) recognized in the latest classification by Hawkes. The cladistic results, and those from earlier cpDNA studies of 35 taxa of the Mexican and Central American species, support four main clades for 17 of the 19 series examined for sect. Petota: 1) the Mexican and Central American diploid species, exclusive of S. bulbocastanum, S. cardiophyllum, and S. verrucosum, 2) S. bulbocastanum and S. cardiophyllum (ser. Bulbocastana, ser. Pinnatisecta), 3) South American diploid species constituting all of ser. Piurana, but also members of ser. Conicibaccata, ser. Megistacroloba, ser. Tuberosa, and ser. Yungasensa, 4) all Mexican and Central American polyploid species (ser. Longipedicellata, ser. Demissa), S. verrucosum (diploid Mexican species in ser. Tuberosa), and South American diploid and polyploid members of ser. Acaulia, ser. Circaeifolia, ser. Commersoniana, ser. Conicibaccata, ser. Cuneoalata, ser. Each of these clades contains morphologically and reproductively very diverse species, and there are no evident morphological features that distinguish the clades. The results suggest a need for a reevaluation of the series and superseries classifications of sect. Petota.