ARS | Publication request: MORPHOLOGICAL AND MOLECULAR SYSTEMATICS OF THE WILD POTATO SOLANUM BREVICAULE COMPLEX

Submitted to: Supplement to American Journal of Botany
Publication Type: Abstract Only
Publication Acceptance Date: August 6, 1996
Publication Date: N/A

Technical Abstract: One of the most difficult taxonomic problems in Solanum sect. Petota involves 37 South American taxa including S. brevicaule and its similar diploid (2n = 2x = 24), tetraploid, and hexaploid species. All are distinguished only by a complex of overlapping character states. Our study reevaluated species boundaries of the S. brevicaule complex with data from morphology, single- to low-copy nuclear RFLP¿s (52 probes) and RAPD¿s (35 10-mer primers). Morphological phenetic results (CVA, PCA, UPGMA) of 250 accessions measured from garden-grown plants (53 characters, averaging 3 plants per accession, two replications) showed no evident clusters. Few species had all accessions clustering exclusively, although some had most accessions clustering. RFLP¿s and RAPD¿s examined 197 and 95 populations, respectively, from a subset of the morphological accessions. Both of these molecular data sets, in contrast, defined the same two groups of species, and accessions showed better species-specific clustering. Spearman-rank correlations of similarity matrices among results were: morphology- RFLP¿s (0.26); morphology-RAPD¿s (0.27); RFLP¿s-RAPD¿s (0.71). These results show the difficulty of using morphology to define species, the better discrimination using RFLP¿s and RAPD¿s and the better concordance of the molecular results.