Brassicas napus, also known as oilseed rape, was formed more than 7000 years ago by allopolyploidy (chromosome doubling from to Brassicas species). Of course the genome mutated further and so it is known today that during this evolution some genes were preserved and further “improved” (e.g. oil biosynthesis genes), whereas others were lost over the course of time (e.g. glusoinolate genes).
Chalhoub et. al now sequenced the genome, because it can help to “provide insights into allopolyploid evolution and its relationship with crop domestication and improvement” (Chalhoub et. al).
What was sequenced?
Young fresh leaves from the Brassica napus French homzygous winter line “Darmor-bzh“.
Sequencing strategy: Whole genome sequencing
- Libraries & Sequencing:
Roche GS FLX: ~ 70 Million reads, Average Read length: ~ 368 bp, Genome coverage: 21.2 %
Sanger BAC Seq: 141k reads, Read length: 650 bp; Genome coverage: 0.1%
Illumina HiSeq: ~375 Million reads, Read length: 36, 76, 108 and 150 bp, Genome coverage: 53.9%
- Data output: 44.146 contigs and 20.702 scaffolds
- Results: A final assembly of 849.7 Mb (using SOAP and Newbler) with 89% nongapped sequences.
After genome assembly the genome was mapped to other species (e.g. B. rapa and B. oleracea) and this helped to find several interesting genes and gene variation that help to understand the complete evolution better.
Read the complete publication here.
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