, Volume 262, Issue 1-2, pp 1-12
Date: 24 Oct 2006

Intragenomic diversity and phylogenetic systematics of wild rosemaries (Rosmarinus officinalis L. s.l., Lamiaceae) assessed by nuclear ribosomal DNA sequences (ITS)

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Abstract

Nuclear ribosomal sequences (ITS) were used to study species boundaries and to infer phylogenetic patterns in wild rosemaries (Rosmarinus officinalis, R. eriocalyx, R. tomentosus). Intragenomic polymorphisms (overlapping peaks and in some cases unreadable sequences) were found throughout the sequencing electrophoretograms of most Rosmarinus accessions. Sequencing the cloned ITS products from representative individuals resulted in 25 ribotypes differing at 59 variable sites. Average sequence divergence among clones was 1.75%, and the most divergent sequences differed by 3.48%. No single ribotype was shared between any two-paired species. The highest values of intragenomic divergence were similar in R. officinalis (1.63%) and R. eriocalyx (1.14%–2.12%), and contrast with those shown by R. tomentosus (0.97%). Sequence data suggest that most divergent rDNA sequences within individuals belong to paralogous loci that apparently are not pseudogenes. A detailed inspection of direct and cloned sequences does not show evidence that the intragenomic polymorphism found is due to interspecific hybridization. Phylogenetic analyses of cloned sequences suggested that both R. officinalis and R. tomentosus were monophyletic, whereas R. tomentosus clones were nested within a paraphyletic R. eriocalyx.