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    Phylogenetics of Taxus Using the Internal Transcribed Spacers of Nuclear Ribosomal DNA and Plastid trnL-F Regions

    Coughlan, Patricia and Carolan, James C. and Hook, Ingrid and Kilmartin, Lisa and Hodkinson, Trevor (2020) Phylogenetics of Taxus Using the Internal Transcribed Spacers of Nuclear Ribosomal DNA and Plastid trnL-F Regions. Horticulturae, 6 (1). p. 19. ISSN 2311-7524

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    Taxus is a genus of trees and shrubs with high value in horticulture and medicine as a source of the anticancer drug paclitaxel. The taxonomy of the group is complex due to the lack of diagnostic morphological characters and the high degree of similarity among species. Taxus has a wide global geographic distribution and some taxonomists recognize only a single species with geographically defined subgroups, whereas others have described several species. To address these differences in taxonomic circumscription, phylogenetic analyses were conducted on DNA sequences using Maximum Likelihood, Bayesian Inference and TCS haplotype networks on single and combined gene regions obtained for the nuclear ribosomal ITS region and the plastid trnL intron and trnL-F intergenic spacer. Evidence is presented for the sister group status of Pseudotaxus to Taxus and the inclusion of Amentotaxus, Austrotaxus, Cephalotaxus and Torreya within Taxaceae. Results are consistent with the taxonomic recognition of nine species: T. baccata, T. brevifolia, T. canadensis, T. cuspidata, T. floridana, T. fuana, T. globosa, T. sumatrana and T. wallichiana, but evidence is found for less species distinction and considerable reticulation within the T. baccata, T. canadensis and T. cuspidata group. We compare the results to known taxonomy, biogeography, present new leaf anatomical data and discuss the origins of the hybrids T. ×media and T. ×hunnewelliana.

    Item Type: Article
    Keywords: biogeography; hybridization; Taxus; nrITS; paclitaxel; phylogenetics; taxaceae; taxol; trnL-F;
    Academic Unit: Faculty of Science and Engineering > Biology
    Faculty of Science and Engineering > Research Institutes > Human Health Institute
    Item ID: 17310
    Identification Number:
    Depositing User: James Carolan
    Date Deposited: 12 Jun 2023 11:22
    Journal or Publication Title: Horticulturae
    Publisher: MDPI
    Refereed: Yes
    Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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