Evaluation of random amplified polymorphic DNA for species identification and phylogenetic analysis in Stylosanthes (Fabaceae)

Random amplified polymorphic DNA (RAPD) was assessed for its suitability as a tool to be used in the identification of taxa from the genus Stylosanthes (Fabaceae, Papilionoideae, Aeschynomeneae). Five random primers were used to 'fingerprint' accessions from seven species in the genus, and generated RAPD profiles that were species-specific, Data were used to examine evolutionary relationships between taxa, employing both clustering and ordination techniques, and the results were compared with those from a previous cladistic analysis of chloroplast DNA (cpDNA) restriction fragments. Both multivariate approaches indicated relationships that were generally similar to those obtained by RFLP analysis of cpDNA. However, while cluster analysis grouped together all accessions within species, ordination placed certain accessions of S. humilis, S. macrocephala and S. capitata into separate groups. Experiments to test the assumed homology of comigrating RAPDs estimated 85.7% homology for accessions within species, and 53.8% homology for accessions between species. The value of RAPD data in systematics is discussed.