Genomic origins of Camelina sativa and chromosome shattering in the genus

Ever since I was an undergraduate researcher, I've been enthralled with the genome of C. sativa. This ancient oilseed and newfound aviation biofuel crop, is an allohexaploid containing the genomes of three different parental species. It was long puzzling to me the identity of these parental species - where did they come from? Do they still exist in the wild? How did they hybridize and undergo polyploidization to produce a robust crop capable of colonizing new niches and dominating as a weed of flax? These were the principal questions I had in the back of my mind as I continued my research in the genus during graduate school. Preliminary data consistently showed that C. hispida was one likely parent of C. sativa, but for so long the others were elusive. It wasn't until last year with the description of a new diploid Camelina species, C. neglecta, that the tables were turned. Research from several groups had identified an accession of C. microcarpa held in the United States Department of Agriculture's seed bank, as being a truly unique and bizarre specimen. In fact, this accession was not C. microcarpa at all, despite many morphological similarities,  it turned out to be the distinct species C. neglecta, and as of now has only found in Southern France. Due to its recent discovery, very little is known about C. neglecta and why it isn't present in regions of high Camelina species diversity (i.e. The Caucasus). However, we now know that this formerly elusive entity was the missing link in the story of Camelina. 

With the immense support of my collaborators at the Central European Institute of Technology (CEITEC) in the Czech Republic, we have finally solved the mystery of C. sativa's origins. Two diploid cytotypes of C. neglecta hybridized and underwent whole genome duplication to form a tetraploid comprising these two C. neglecta genomes. Next a C. hispida diploid joined the mix and subsequently hybridized with this tetraploid resulting in an allohexaploid Camelina species known as C. microcarpa. About 5,000 to 10,000 years ago C. microcarpa became the target of selection for agricultural traits starting the process of domestication that ultimately resulted in the oilseed crop C. sativa. In addition  to these insights, cutting edge cytogenetics was used to infer the ancestral Camelina genome structure which gave rise to all Camelina species. Interestingly, this study also uncovered evidence of complex chromosomal rearrangements, a phenomena associated with many human genetic diseases. 

Congratulations to Teri, Milan, Ihsan, and Martin for all of the hard work and the fantastic new publication in The Plant Cell: http://www.plantcell.org/content/early/2019/08/28/tpc.19.00366