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Abstract Detail


An, Hong [1], Gaynor, Michelle [2], Gebken, Sarah [3], Qi, Xinshuai [4], Barker, Michael [5], Pires, Joseph Chris [6].

Origin(s) of a hybrid: History of allopolyploid Brassica napus using genome-wide data.

Brassica napus is an allopolyploid species (AACC, 2n=38) hybridized from two diploid species, Brassica rapa (AA=20) and Brassica oleracea (CC=18), between 7,500 and 12,500 years ago. It has three subspecies recognized as economically important crops including rapeseed (canola), rutabaga and Siberian kale. Although the progenitor species of B. napus are already known, it remains a mystery as to whether hybridization occurred once or multiple times, and when and where the original hybridization occurred. We used RNA-seq and genome-survey sequencing (GSS) data to further understand the origin(s) of B. napus. We obtained 24,193 SNPs between 183 B. napus and 102 B. rapa based on A sub-genome and 23,387 SNPs among B. napus and 62 B. olearcea + wild C species based on C sub-genome. Using these SNPs, we generated two nuclear maximum-likelihood (ML) phylogenies which both showed consistent genetic clusters and indicated a single origin of Brassica napus. Subsequently, we de novo assembled sections of the chloroplast and mitochondrial genomes. By doing this, we constructed two ML phylogenies according to 62 single copy (LSC and SSC) genes in chloroplast and 42 mitochondrial genes separately. The subspecies were not distinguishable based on our phylogenies, which supports that the organelle genomes were more conserved than the nuclear genome. Phylogenies based on the chloroplast and mitochondrial genes gave weak support for multiple origins of B. napus, consistent with previous studies that used organelle data. The results obtained in this study highlight that separate parts of the genome with varying patterns of inheritance provide provide insight into the origin and subsequent introgression of B. napus infer different origin stories as the nuclear genome points to a single origin and the organelle genome indicates multiple origins of B. napus.

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1 - Biological science, Columbia, MO, 65211, USA
2 - University of Central Florida , 4110 Libra Drive, Orlando, FL, 32816, USA
3 - University of Missouri - Columbia, Biological Engineering, 416 S 6th St, Columbia, MO, 65201, USA
4 - University Of Arizona, 2929 E 6th Street Apt 210, Tucson, AZ, 85716.0, United States
5 - Department Of Ecology & Evolutionary Biology, P.O. Box 210088, Tucson, AZ, 85721, United States
6 - University of Missouri, Biological Sciences, Columbia, MO, 65211


Presentation Type: Oral Paper
Session: 1, Phylogenomics I
Location: 114/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 10:45 AM
Number: 1010
Abstract ID:258
Candidate for Awards:None

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