Genetic and phenotypic variation among Turkish terrestrial orchid species as revealed by RAPD and morphological characteristics

Abstract

Terrestrial orchid species are natural sources of salep and a closely related group of plant species widely distributedthroughout Turkey. The phylogenetic relationship among fourteen different tuber-producing orchid species was investigated afteranalyzing phenotypic and genetic variation within and among the natural population through fifteen morphometric traits and tenrandom amplified polymorphic DNA (RAPD) primer combinations. Statistical analyses (principal component analysis (PCA), principalcoordinate analysis (PCoA), and cluster analysis) using the generated data identified taxonomic and genetic distance within the studiedplant samples. The results of PCA from morphological traits show that there are no major groupings within and among different speciesinstead somehow overlapping with few distinctly characterized species. In addition, the UPGMA-based phenogram with Euclideandistance (0–1) produces five major clusters among the studied orchid species according to their taxonomic status with few exceptions.On the other hand, PCoA and the phylogenetic dendrogram with the coefficient (0.56–0.79) from RAPD band profiles determine thetrue genetic diversity of those species. Although both combinations of genetic and phenotypic characteristics reveal the phylogeneticrelationship of some those studied species very effectively, they are not clear for others. These results suggest that in the natural populationof terrestrial orchid species significant amounts of gene flow are ongoing at intra/interspecies level. Therefore, it is recommended thatconservation studies of these groups of orchid species should be done as a geographical unit rather than according to taxonomic status.