Abstract Detail

Comparative Genomics/Transcriptomics

Thomas, Shawn [1], Abrahams, Richard [2], Harkess, Alex [3], Washburn, Jacob [4], Pires, Joseph [5], Arias, Tatiana [6].

Phylogenetically localizing and dating the mesohexaploidy of the tribe Brassiceae.

Whole Genome Duplication (WGD) is a major driver of genomic and phenotypic variation in genomes, but accurately placing WGD events on phylogenies remains challenging, especially in large families. The crop Brassicas, within the Brassicaceae (mustard) family, have triplicated genomes compared to Arabidopsis. Evidence suggests that this mesohexaploidy resulted from two WGD events. The age of these events and if they are found only within the core Brassiceae or shared across the entire tribe remains unknown. In this study we use phylogenomic approaches to both localize and date these WGD events. Using genome skim sequencing and transcriptome assemblies across the tribe we built a chloroplast tree and a nuclear-based species tree to resolve the phylogeny and place and date the WGD events. Interestingly we see conflict in these two topologies at early diverging lineages, subtribes Vella and Zilla, which could be the result of ILS or ancient gene flow between these lineages. Preliminary analysis suggests that the WGD events occur on the same branch and are shared across all Brassiceae. Furthermore we have dated this WGD event using our well-supported chloroplast phylogeny, with robust fossil calibrations in the Rosids. Understanding the timing and placement of the Brassiceae whole genome triplication is crucial to further elucidate the evolutionary history of the tribe Brassiceae.

1 - University Of Missouri, Division Of Biological Sciences, 1201 Rollins Street, 311 Bond Life Sciences Center, Columbia, MO, 65211, United States
2 - Yale University, Department of Ecology and Evolutionary Biology, New Haven, CT, 06520, USA
3 - Auburn University, HudsonAlpha Institute For Biotechnology, Harkess Lab, HudsonAlpha Institute For Biotechnology, 601 Genome Way, Huntsville, AL, 35806, United States
4 - USDA-ARS, Plant Genetics Research Unit, Columbia, MO, 65211, USA
5 - New York Botanical Garden, International Plant Science Center, Bronx, NY, 10458, USA
6 - Marie Selby Botanical Gardens, Sarasota, FL, 34236, USA

Keywords:
Transcriptomics
phylogenomics
whole genome duplication
polyploidy
Brassicaceae.

Presentation Type: Oral Paper
Number: CGT4002
Abstract ID:91
Candidate for Awards:Margaret Menzel Award