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Abstract Detail


Genetics Section

Wickett, Norman J. [1], Wall, P. Kerr [2], Yoder, John [3], dePamphilis, Claude W. [4].

Genome evolution in the Orbanchaceae: evidence from large-scale EST studies and the Parasitic Plant Genome Project.

The Orobanchaceae comprises 84 genera and >2000 species that span the continuum of parasitism from facultative hemiparasites to fully non-photosynthetic holoparasites. With an independent genome sequencing project underway for a closely related, non-parasite, Mimulus, there exists a phylogenetic framework to test hypotheses of genome evolution associated with the transitions between completely autotrophic plants and parasites, as well as between parasites with varying degrees of host reliance. The goal of the Parasitic Plant Genome project is to compare transcriptomes across both the diversity of these parasites represented by Triphysaria (facultative hemiparasite), Striga (obligate hemiparasite), and Orobanche (obligate holoparasite), as well as between and among stage-specific sequenced cDNA. Ultimately, these data will be used to investigate the role of specific genes in specific parasite functions, with particular emphasis on the organ that forms the bridge between parasite and host the haustorium. However, initial data from this project allows us to examine the history of genome size. Here, we discuss an analysis of the rate of synonymous substitutions (Ks) of paralogous genes in Triphysaria from a set of Sanger-sequenced ESTs. The distribution of Ks values of gene-pairs suggests that a large-scale duplication event occurred relatively recently in the history of Triphysaria. An analysis of available EST data from Mimulus reveals that the non-parasite does not share this duplication event, suggesting that the genome duplication is specific to parasites. Corroboration of this event can be investigated by the identification of genes retained following the duplication, and gene family phylogenetic analyses. The impact of high-throughput cDNA sequence data on the placement of the duplication relative to other Orbanchaceae is also addressed.


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1 - Penn State University, Biology, 403 Life Sciences Building, University Park, PA, 16802, USA
2 - Pennsylvania State University, Department of Biology, 403 Life Sciences Building, University Park, Pennsylvania, 16802, USA
3 - University of California-Davis, Plant Sciences, Davis, CA, 95616, USA
4 - Pennsylvania State University, Department of Biology and Institute of Molecular Evolutionary Genetics, University Park, Pennsylvania, 16801, USA

Keywords:
parasitic plants
Genome duplication
polyploidy
EST
Orobanchaceae.

Presentation Type: Oral Paper:Papers for BSA Sections
Session: 13
Location: Cottonwood C/Snowbird Center
Date: Monday, July 27th, 2009
Time: 10:45 AM
Number: 13003
Abstract ID:781


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