Submitted to: Solanaceae International Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/29/2007
Publication Date: 7/30/2006
Citation: Alvarez, N., Peralta, I., Spooner, D.M. 2006. Morphological evaluation of the solanum brevicaule complex: A replicated field trial from Argentina [abstract]. Solanaceae International Congress Proceedings. p. 146.
Technical Abstract: The Solanum brevicaule complex is a group of very similar wild potato (Solanum sect. Petota) species defined on morphological similarity. They are generally freely intercrossable to each other and to the potato cultivars. They include diploids (2n=2x=24), tetraploids (2n=4x=48) and hexaploids (2n=6x=72), and are distributed from Peru to central Argentina. Every potato taxonomist treating this group has provided different interpretations of the number of species, ranging from two to over 20, and the complex presents one of most intractable taxonomic problems in the section. Our morphological field study of germplasm accessions planted in a common field plot in Mendoza Argentina is a replication of one in Wisconsin, USA. We assessed 51 morphological characters from 178 accessions of three individuals per accession, for a total of over 27,000 individual measurements. Although correlation coefficients between studies are low (r = 0.14), there are many points of agreement. For example, the only support for species was from canonical variates analysis using a range of overlapping traits (polythetic support). Some phenetically distinctive species (e.g., S. vernei) clustered. However, unlike the Wisconsin results, and recently published molecular (AFLPs, RAPDs, low-copy nuclear RFLPs) results, the group did not form "northern" (Peru) and "southern" (Bolivia and Argentina) clusters. The Argentinean results better supported some species, in agreement with AFLP data (e.g., S. avilesii, S. spegazzinni). They also showed no support for S. oplocense, that likewise was not supported in the AFLP study, but was in the Wisconsin study. We conclude that there is no easy resolution to the taxonomy of the Solanum brevicaule complex, and that many of the species will be relegated to synonymy. We are continuing to study the group with a world-wide assemblage of herbarium specimens, including types, and with DNA sequence data to be integrated into a broader study of the entire section.