Species relationships between a wild tetraploid potato species,Solanum acaule bitter, and its related species as revealed by rflps of chloroplast and nuclear DNA

Abstract

Solanum acaule Bitter is a wild, disomic tetraploid potato species widely distributed in the South America. In this study, species relationships between eight accessions ofS. acaule and 108 accessions of 27 morphologically closely related species were investigated using chloroplast and nuclear DNA RFLPs. Chloroplast DNA types were determined for most of the accessions based on restriction digestion patterns of entire chloroplast DNA. C type chloroplast DNA was common inS. acaule andS. albicans (a hexaploid derivative fromS. acaule), which was also found inS. megistacrolobum, S. sanctae-rosae,S. raphanifolium, and several other Peruvian species in seriesTuberosa. Nuclear DNA was analyzed by Southern hybridization with 31 single-copy RFLP probes. One hundred and thirty-four bands were scored, from which a UPGMA dendrogram was constructed to show overall similarities among accessions.Solanum acaule andS. albicans (andS. demissum) formed a cluster with a high similarity, and then, this group was clustered withS. megistacrolobum andS. sanctae-rosae. The resulting cluster was well separated from other clusters. Thus, we suggest that an initial tetrasomic tetraploid arose from eitherS. megistacrolobum orS. sanctae-rosae. Interestingly, a Mexican hexaploid speciesS. demissum showed the closest similarity toS. acaule andS. albicans, suggesting that they shared a common ancestry.