Abstract Species of Gentiana section Cruciata are highly similar in their morphological and anatomical characteristics, which complicates their taxonomic delimitation and phylogenetic interpretation. Molecular markers increasingly complement traditional morphology-based approaches, and the intergenic spacer of the 5S rRNA gene cluster (5S rDNA IGS) represents a promising candidate for such analyses. In this study, genetic variation among 10 species within section Cruciata was investigated using sequences of the 5S rDNA IGS region, and its potential utility for DNA barcoding and phylogenetic analysis was evaluated. Analysis of 38 cloned PCR products revealed a structural organization of the IGS region typical of other Gentiana species, including conserved regulatory elements, and a high level of nucleotide sequence similarity (91.2–99.5%). Interspecific polymorphism was comparable to intragenomic variation. Sequence alignment and clustering distinguished two groups of species that differed in their IGS nucleotide sequences. The resulting taxonomic grouping is generally consistent with previously reported phylogenetic relationships inferred from other molecular markers. The high similarity of IGS sequences among species of section Cruciata suggests their relatively recent divergence. Notably, G. cruciata, despite its migration from Asia to Europe, retained IGS region characteristics typical of the section.
Mel’nyk et al. (Tue,) studied this question.