Sequencing of the camelina (Camelina sativa) genome revealed that the genome consists of three parental subgenomes. However, how the hexaploid camelina genome originated and how the three subgenomes are related to other genomes in the genus Camelina remained unknown. We tackled these questions by using comparative chromosome painting, genomic in situ hybridization, and multi-gene phylogenetic analyses. We aimed to identify the most probable parental genomes of the hexaploid camelina and moreover to understand how its genome is related to genomes of other Camelina species.
Genomes of diploid camelinas (C. hispida, n = 7 chromosomes; C. laxa, n = 6; and C. neglecta, n = 6) originated from an ancestral n = 7 genome. The allotetraploid C. rumelica genome (n = 13, N6H genome) arose from hybridization between diploids C. neglecta (n = 6, N6) and C. hispida (n = 7, H), and the N subgenome has been substantially reshuffled by chromosomal rearrangements. The allohexaploid genomes of C. sativa (n = 20, N6N7H) originated through hybridization between an auto-allotetraploid C. neglecta-like genome (n = 13, N6N7) and C. hispida (n = 7, H), and the three subgenomes remained overall stable since the genome merger. Remarkably, the ancestral and diploid Camelina genomes were shaped by complex chromosome shattering, resembling similar events associated with human disorders.
The Camelina story was published in Plant Cell!
The paper was highlighted by a Plant Cell editorial by Jen Mach: Camelina: A History of Polyploidy, Chromosome Shattering, and Recovery.