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Abstract Detail


Lam, Vivienne K.Y. [1], Soto Gomez, Marybel [1], Graham, Sean W. [1].

The highly reduced plastid genome of mycoheterotrophic Sciaphila densiflora (Triuridaceae) is colinear with its close green relatives and under strong purifying selection.

The enigmatic monocot family Triuridaceae provides a useful system for studying the effects of an ancient loss of photosynthesis on plant genomes, as its members are all mycoheterotrophic and achlorophyllous. However, few studies have placed the family in a comparative context, and its phylogenetic placement is only partly resolved. It also remains unclear whether any taxa in this family have retained a plastid genome. Here we used genome-survey sequencing to retrieve plastid genome data for Sciaphila densiflora (Triuridaceae) and ten autotrophic relatives in the orders Dioscoreales and Pandanales. We recovered a highly reduced plastome for Sciaphila that is nearly colinear with its photosynthetic relatives, and inferred a well supported placement of Triuridaceae in Pandanales. Its phylogenetic placement is well supported and robust to a diverse range of analytical assumptions for phylogenetic inference, and is congruent with recent findings based on nuclear and mitochondrial data. The genes retained in the Sciaphila densiflora plastid genome are involved in translation and other non-photosynthetic functions, and nearly all of its protein-coding complement is under strong purifying selection. Our study confirms the utility of whole plastid genome data in phylogenetic studies of highly modified heterotrophic plants, even when they have substantially elevated rates of substitution.

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1 - University of British Columbia, Department of Botany, Vancouver, BC, V6T 1Z4, Canada

gene loss
genome reduction
purifying selection
heterotrophic plants
rate elevation.

Presentation Type: Oral Paper:Papers for Topics
Session: 73
Location: Salon 9/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 1:45 PM
Number: 73002
Abstract ID:972
Candidate for Awards:None

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