Plant Cell 31: 2596-2612.
Complexes of diploid and polyploid species have formed frequently during the evolution of land plants. In false flax (Camelina sativa), an important hexaploid oilseed crop closely related to arabidopsis, putative parental species as well as origin of other Camelina species remained unknown. By employing BAC-based chromosome painting, genomic in situ hybridization (GISH) and multi-gene phylogenetics we aimed to elucidate the origin and evolution of the polyploid complex. Genomes of diploid camelinas (C. hispida, n = 7; C. laxa, n = 6; and C. neglecta, n = 6) originated from an ancestral n = 7 genome (n = 7). The allotetraploid genome of C. rumelica (n = 13, N6H) arose from hybridization between diploids C. neglecta (n = 6, N6) and C. hispida (n = 7, H), and the N subgenome has undergone a substantial post-polyploid fractionation. The allohexaploid genomes of C. sativa and C. microcarpa (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 chromosomal rearrangements, resembling those associated with human disorders and resulting in the origin of genome-specific shattered chromosomes.