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Abstract Detail

Molecular Ecology and Evolution

Gerelle, Wesley [1], Lam, Vivienne K. Y. [1], Wulff, Adrien [2], Hollingsworth, Michelle [3], Hollingsworth, Peter [3], Graham, Sean W. [4].

Molecular evolution of plastid genes in a heterotrophic conifer, Parasitaxus usta (Podocarpaceae).

The New Caledonian Parasitaxus usta may be the sole mycoheterotrophic conifer. It appears to derive its carbon budget and other nutrients from fungi that reside in a “host” conifer, Falcatifolium taxoides (Podocarpaceae), is unable to photosythesize, and has lost multiple photosynthesis-related genes from its plastid genome. Here we investigate the evolution of nine genes in Parasitaxus, a subset of those that may still be functional in the plastid genome, for evidence of purifying selection, by examining dN/dS ratios. All nine have retained open reading frames (ORFs). Seven show strong evidence of purifying selection (five ribosomal protein genes, a fatty-acid biosynthesis gene, and an ATP synthase subunit gene). An additional ATP synthase subunit gene, atpB, and the gene for the plastid maturase enzyme, matK (which is involved in plastid group II intron splicing), appear to be evolving neutrally, despite both having open reading frames. Other group-II introns are retained in the Parasitaxus genome, including those found in three of the genes for which we also found evidence of purifying selection (rpl2, rpoC1 and rps12). This indicates either that matK is still functional, or that a secondary maturase is involved in splicing the introns. The atpB locus codes for the beta subunit of ATP synthase, and includes the active site of ATP synthase. Other plastid-encoded atp subunits have been lost from the plastid genome. However, the atpE subunit is retained, and we found evidence of purifying selection for it. In the future we intend to expand these analyses to the remaining protein-coding complement of the Parasitaxus plastid genome.

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1 - University of Britsh Columbia, Department of Botany, Biodiversity Research Centre, 2212 Main Mall, Vancouver, BC, V6T 1Z4, Canada
2 - Université de la Nouvelle-Calédonie, Laboratoire Insulaire du Vivant et de l'Environnement, Nouméa, 98851, New Caledonia
3 - Royal Botanic Garden Edinburgh, Edinburgh, EH3 5LR, UK
4 - University of British Columbia, Botany, 3529 - 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada

Heterotrophic plants
plastid genome
Molecular Evolution.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PME012
Abstract ID:747
Candidate for Awards:Genetics Section Poster Award

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