Abstract Detail

Phylogenomics

Darby, Hayley [1], Merckx, Vincent S.F.T. [2], Graham, Sean W. [1].

Plastid genome degradation in fully and partially mycoheterotrophic eudicots.

The evolutionary loss of photosynthesis can have profound consequences for plant genomes, especially the plastid genome. Photosynthetic land plants are in general stable in terms of genome size, content and structure, but those of heterotrophic plants (mycoheterotrophs, parasitic plants) are substantially more varied. They frequently show evidence of pseudogenization or gene loss due to relaxation of purifying selection on photosynthetic and other genes. Full mycoheterotrophy, in which plants obtain all of their nutritional needs from mycorrhizal or saprophytic fungal associates, has originated around 50 times in land plants. The majority of these origins were in monocots, but there were also around seven or eight distinct origins in the eudicots across three families (Ericaceae, Gentianaceae and Polygalaceae). Here we present complete plastid genomes from photosythetic, and partially and fully mycoheterotrophic lineages in these families, with a focus on genome architecture, and gene content and molecular evolution. We document a spectrum of gene losses, ranging from the highly reduced genome of Voyria (Gentianaceae) to what appears to be a recent loss of photosynthesis in Exochaenium (Gentianaceae). We also place these mycoheterotrophic taxa in a core eudicot-wide phylogenetic analysis.

1 - University of British Columbia, Department of Botany, Vancouver, BC, V6T 1Z4, Canada
2 - Biology, M.H. Tromplaan 152, Oegstgeest, N/A, 2341TE, Netherlands

Keywords:
plastid genome
genome reduction
gene loss
mycoheterotrophy
heterotrophic plants
Gentianaceae
Polygalaceae.

Presentation Type: Oral Paper:Papers for Topics
Session: 73
Location: Salon 9/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 2:45 PM
Number: 73006
Abstract ID:1066
Candidate for Awards:Margaret Menzel Award