Improved phylogenetic resolution of toxic and non-toxic Alexandrium strains using a concatenated rDNA approach
► 27 Alexandrium strains were tested for PSP presence and sequenced for ∼5.2 kb rDNA. ► A concatenated approach inferred the Alexandrium phylogeny, increasing resolution. ► The terminal tamarensis-complex produces more PSP analogues than basal clades. ► Two A. fundyense rDNA copies show presence of...
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Published in | Harmful algae Vol. 10; no. 6; pp. 676 - 688 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Kidlington
Elsevier B.V
01.09.2011
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | ► 27
Alexandrium strains were tested for PSP presence and sequenced for ∼5.2
kb rDNA. ► A concatenated approach inferred the
Alexandrium phylogeny, increasing resolution. ► The terminal
tamarensis-complex produces more PSP analogues than basal clades. ► Two
A. fundyense rDNA copies show presence of chimeric sequences within GenBank. ► Diversification maybe over-estimated and
A. tamarense strains misidentified.
Dinoflagellates of the genus
Alexandrium are known producers of paralytic shellfish toxins. Species within the genus have similar phenotypes making morphological identification problematical. The use of
Alexandrium rDNA sequence data is therefore increasing, resulting in the improved resolution of evolutionary relationships by phylogenetic inferences. However, the true branching pattern within
Alexandrium remains unresolved, with minimal support shown for the main phylogentic branch. The aim of this study is to improve phylogenetic resolution via a concatenated rDNA approach with a broad sample of taxa, allowing inference of the evolutionary pattern between species and toxins. 27
Alexandrium strains from 10 species were tested with HPLC for PSP toxin presence and additionally sequenced for 18S, ITS1, 5.8S, ITS2 and 28S rDNA before being phylogenetically inferred together with all available orthologous sequences from NCBI. The resulting alignment is the largest to date for the genus, in terms of both inferred characters and taxa, thus allowing for the improved phylogenetic resolution of evolutionary patterns there in. No phylogenetic pattern between PSP producing and non-producing strains could be established, however the terminal
tamarense complex was shown to produce more PSP analogues than basal clades. Additionally, we distinguish a high number of polymorphic regions between the two copies of
A. fundyense rDNA, thus allowing us to demonstrate the presence of chimeric sequences within GenBank, as well as a possible over estimation of diversification within the
tamarense complex. |
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Bibliography: | http://dx.doi.org/10.1016/j.hal.2011.05.003 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1568-9883 1878-1470 |
DOI: | 10.1016/j.hal.2011.05.003 |