Abstract Detail

Systematics Section

Arias, Tatiana [1], Edger, Patrick [1], Tang, Michelle [2], Pires, J. Chris [1].

Phylogenetics, genome evolution and biogeography of the Brassica crops and wild relatives (Brassiceae, Brassicaceae): Understanding the origin and domestication of mustards.

The Brassica crops and allied species are model organisms for the study of phylogenetics, biogeography and ultimately plant domestication. The tribe Brassiceae with 54 genera and approximately 240 species contains more than 30 research and agricultural species such as the Brassica crops. They are grown globally for oil, condiments, vegetables, fodder, medicine, and bio-diesel fuels. This research focuses on developing a multi-locus molecular phylogeny in order to unravel genome evolution, biogeography and domestication history of the Brassiceae. Relationships and circumscription among the genera and subtribes have been a matter of debate for many years. The Brassiceae has long been identified as monophyletic among the tribes of the Brassicaceae, but the subtribes recognized within the tribe are still under taxonomic debate. The tribe phylogeny has been the focus of intensive research in the past 30 years. However, its reconstruction has been challenging since speciation events have been the result of complex genomic reshuffling throughout the tribe, including hybridization, introgression, and polypoidy. The genomes of “diploid” species in the tribe have an ancient hexaploid event (7.9 and 14.6 Mya) on top of three whole genome duplication events shared with Arabidopsis. Results from a four-gene chloroplast phylogeny recovered seven strongly supported lineages within the tribe. Vella, Zilla and allied genera are the basal most lineages in the tribe. The Nigra clade is the sister group to core Brassiceae (Cakile, Crambe, and Oleraceae lineages). A whole chloroplast phylogeny has been build for members of the seven lineages in the tribe. These results have allowed us to infer the phylogenetic placement and date of whole genome duplications (WGDs) specific to the tribe. The tribe origin is coincidental with its center of diversity in the Mediterranean. We will present historical biogeographical analyses, including divergence times in order to draw strong conclusions about speciation events in the group. Each of the seven lineages is strongly associated to a particular type of soil and environmental conditions.

Broader Impacts:

1 - University of Missouri, Biological Sciences, 1201 Rollins Road, 311 Life Sciences Center, Columbia, Missouri, 65211, USA
2 -

Keywords:
Brassiceae
Brassicaceae
phylogenetics
phylogenomics
mediterranean
chloroplast genome
whole-genome duplication.

Presentation Type: Oral Paper:Papers for Sections
Session: 56
Location: 556B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 1:45 PM
Number: 56004
Abstract ID:91