Orchid Biology: Darwin`s Contrivances 150 Years Later
Chase, Mark , Ovidiu, Paun .
Epigenetics and allotetraploids in Dactylorhiza (Orchidaceae).
Hybridization and polyploidy are potent forces that have regularly stimulated plant evolution and adaptation. Dactylorhiza majalis s.s., D. traunsteineri s.l.and D. ebudensis are three allopolyploid species of a polyploid complex formed through unidirectional hybridization between the widespread diploids D.fuchsii and D. incarnata. Differing considerably in geographical extent and ecological tolerance, the three allopolyploids together provide a useful system to explore genomic responses to allopolyploidization and reveal their role in adaptation to contrasting environments. Analyses of gene expression show a significant increase in number of gene variants expressed in the allopolyploid lineages(including novel alleles), providing clear evidence of increased biological complexity following allopolyploidization. The epigenetic variation released bygenome doubling has been restructured in species-specific patterns that reflect their recent evolutionary history and have an impact on their ecology and evolution, hundreds of generations after their formation. The stable epigenetic divergence between the allopolyploids is largely responsible for persistent ecological differences, which then set the stage for species-specific genetic patterns to accumulate in response to further selection and/or drift. Using NGS technologies, we are currently comparing mRNA expression levels between the allopolyploids and their parents. During this investigation we have been constructing reference transcriptomes for the two diploid parents, which contribute important genomic resources for Orchidaceae in general. In addition to stabilizing the allopolyploid genome, genetic and epigenetic alterations are key determinants of adaptive success of the new polyploid species after recurrent allopolyploidization events, potentially triggering reproductive isolation between the resulting lineages.
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1 - Royal Botanic Gardens - Kew, Jodrell Laboratory, Kew Road, Richmond, N/A, TW9 3DS, United Kingdom
2 - University Of Vienna, Department For Systematic And Evolutionary Botany, Rennweg 14, Vienna, Austria, A-1030, United Kingdom
Presentation Type: Symposium or Colloquium Presentation
Location: Franklin B/Hyatt
Date: Wednesday, July 11th, 2012
Time: 4:15 PM