Origin and Evolution of Diploid and Allopolyploid Genomes Were Accompanied by Chromosome Shattering.

Complexes of diploid and polyploid species have formed frequently during the evolution of land plants. In false flax (), an important hexaploid oilseed crop closely related to Arabidopsis (), the putative parental species as well as the origin of other species remained unknown. By using bacterial artificial chromosome-based chromosome painting, genomic in situ hybridization, and multi-gene phylogenetics, we aimed to elucidate the origin and evolution of the polyploid complex. Genomes of diploid camelinas (, = 7; , = 6; and , = 6) originated from an ancestral = 7 genome. The allotetraploid genome of ( = 13, NH) arose from hybridization between diploids related to ( = 6, N) and ( = 7, H), and the N subgenome has undergone a substantial post-polyploid fractionation. The allohexaploid genomes of and ( = 20, NNH) originated through hybridization between an auto-allotetraploid -like genome ( = 13, NN) and ( = 7, H), and the three subgenomes have remained stable overall since the genome merger. Remarkably, the ancestral and diploid genomes were shaped by complex chromosomal rearrangements, resembling those associated with human disorders and resulting in the origin of genome-specific shattered chromosomes.plantcell;31/11/2596/FX1F1fx1.