Chloroplast phylogenomics further supports the placement of Hyssopus within Dracocephalum (Lamiaceae: Nepetinae)

Background and aims – Dracocephalum nuratavicum , D. komarovii , and D. seravschanicum are narrowly distributed species from Uzbekistan that have not previously been included in plastome-based phylogenetic studies of Dracocephalum . This study aimed to assemble and compare their complete chloroplast genomes and to test the placement of Hyssopus within Dracocephalum . Material and methods – Complete chloroplast genomes were generated for three Uzbek species using high-throughput sequencing. Comparative plastome analyses were carried out using accessions representing Dracocephalum and related taxa, and phylogenetic relationships were reconstructed from complete chloroplast genome sequences with maximum likelihood analyses. Key results – The plastomes ranged from 149,819 to 151,181 base pairs and showed the typical quadripartite structure with 133 genes. Overall genome structure and gene content were highly conserved across the sampled taxa. Several highly variable regions were detected, especially in the intervals psbD – rps16 and trnR -ACG– rrn16 . Phylogenetic analyses placed D. nuratavicum , D. komarovii , and D. seravschanicum within well-supported Dracocephalum lineages. Hyssopus officinalis and H. cuspidatus were nested within the Dracocephalum clade. Conclusion – The newly generated plastomes provide the first genomic evidence for the phylogenetic placement of three poorly studied Uzbek species and further support the inclusion of Hyssopus within Dracocephalum . These results improve the taxonomic framework of the group and provide useful genomic resources for future systematic and conservation studies.

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