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A molecular phylogenetic study of Arnica (Asteraceae): Low chloroplast DNA variation and problematic subgeneric classification
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Systematic Botany.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Systematic Botany.
2007 (English)In: Systematic Botany, ISSN 0363-6445, Vol. 32, no 4, 917-928 p.Article in journal (Refereed) Published
Abstract [en]

DNA sequences from five chloroplast DNA regions (the rpl16 and rps16 introns and the psbA-trnH, ycf4-cemA, and trnT-L spacers), and the nuclear ribosomal internal and external transcribed spacer (ITS and ETS) regions, were analyzed using maximum parsimony and Bayesian methods to explore the putatively complicated history of the mainly North American genus Arnica. The chloroplast regions were found to contain minimal variation in Arnica. Of 3710 nucleotides, only 119 were variable and 45 informative. However, combined with the ribosomal DNA data, the analysis yielded a number of well-supported clades. Strong support for the monophyly of Arnica was found in both the separate and combined analyses but none of the five currently recognized subgenera was resolved as monophyletic in any of the analyses. Arnica (Whitneya) dealbata and A. mallotopus (Mallotopus japonicus), two species that were previously placed outside Arnica, were confidently confirmed as members of the genus. The analyses revealed that A. nevadensis (subg. Austromontana) is most closely related to A. dealbata and that A. mallotopus forms a strongly supported clade with A. unalaschcensis (subg. Andropurpurea). Earlier biogeographical hypotheses that suggested an arctic origin and southward spread of the genus are not supported by our analyses. Hybridization, homoplasy, and rapid evolution are possible explanations for conflicts between the chloroplast and nuclear ribosomal data sets and for low support of the deeper nodes.

Place, publisher, year, edition, pages
2007. Vol. 32, no 4, 917-928 p.
Keyword [en]
Arnica, Asteraceae, chloroplast, Compositae, dealbata, ETS, ITS, mallotopus, phylogeny
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-96739ISI: 000251559200020OAI: oai:DiVA.org:uu-96739DiVA: diva2:171415
Available from: 2008-02-21 Created: 2008-02-21 Last updated: 2012-11-06
In thesis
1. Phylogenies and Secondary Chemistry in Arnica (Asteraceae)
Open this publication in new window or tab >>Phylogenies and Secondary Chemistry in Arnica (Asteraceae)
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The genus Arnica (Asteraceae) was investigated for phylogenetic relationships and sesquiterpene lactone (STL) content with the aims to trace the evolutionary history of the genus and to investigate possible congruencies between DNA sequence data, secondary chemistry, and biological activity.

Complex evolutionary patterns in Arnica are evident from phylogenetic analyses of chloroplast regions (the rpl16 and rps16 introns and the psbA–trnH, ycf4–cemA, and trnT–L spacers), nuclear ribosomal regions (the internal and external transcribed spacers) and the nuclear low-copy DNA region coding for the second largest subunit of RNA polymerase II (RPB2) between exons 17 and 23. Polymorphism was detected in nuclear ribosomal and low-copy regions, likely caused by polyploidy and agamospermy. Lineage sorting and/or hybridization is a possible explanation for incongruencies between topologies of the different DNA regions. None of the five subgenera in Arnica constitute a monophyletic group according to any of our analyses.

Sesquiterpene lactone profiles were compared to nuclear ribosomal DNA data using phylogenetic inference and principal component analysis for 33 accessions of 16 species. Clusters supported by both STL chemistry and ribosomal DNA sequence data consist of multiple accessions of the same species (e.g. A montana and A. longifolia), indicating that these species are well defined both genetically and chemically, based on our sampling. Support for subspecies classification of A. chamissonis and A. parryi was found in chemical data. For the first time STLs are reported from subtribe Madiinae, sister to Arniciinae.

Anti-inflammatory properties, as measured by inhibition of human neutrophil elastase release from neutrophils and inhibition of the binding of transcription factor NF-κB to DNA, were investigated for extracts of 12 Arnica species. Arnica montana, A. chamissonis and A. longifolia accessions show high inhibitory effects in both bioassays. Generally, species with a more diverse STL chemistry also possess the strongest inhibitory activity in the bioassays.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 57 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 392
Biology, phylogeny, ITS, ETS, RPB2, sesquiterpene lactones, PCA, bioassay, NF-κB, neutrophil, chloroplast, Biologi, Arnica, Asteraceae
urn:nbn:se:uu:diva-8459 (URN)978-91-554-7092-0 (ISBN)
Public defence
2008-03-14, Lindahlsalen, EBC, Norbyvägen 18A, Uppsala, 10:00
Available from: 2008-02-21 Created: 2008-02-21Bibliographically approved

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