Brassicales: an update on chromosomal evolution and ancient polyploidy

• Published in: Plant systematics and evolution Vol. 304; no. 6; pp. 757 - 762
• Main Author: Lysak, Martin A.
• Format: Journal Article
• Language: English
• Published: Vienna Springer-Verlag GmbH 01.06.2018; Springer Vienna; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Brassicaceae; Brassicales; Capparaceae; Chromosome number; Chromosomes; Cleomaceae; data collection; genome; Genomes; Historical metallurgy; Life Sciences; Mustard; Original Article; Phylogenetics; Phylogeny; Plant Anatomy/Development; Plant Ecology; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; Polyploidy; Resedaceae; Tropaeolaceae; Paleopolyploidy; Whole-genome duplications; Ancestral genome evolution; Paleogenomics; Post-polyploid diversification; Chromosome number evolution
• ISSN: 0378-2697; 1615-6110; 2199-6881
• DOI: 10.1007/s00606-018-1507-2

Brassicales comprise 17 families, c. 400 genera and more than 4600 species. Despite the mustard family (crucifers, Brassicaceae) continuing to be the subject of intensive research, the remaining 16 families are largely under studied. Here I summarize the available data on chromosome number and genome size variation across Brassicales in the context of a robust phylogenetic framework. This analysis has revealed extensive knowledge gaps in karyological data for non-crucifer and species-rich families in particular (i.e., Capparaceae, Cleomaceae, Resedaceae and Tropaeolaceae). A parsimonious interpretation of the combined chromosomal and phylogenetic data set suggests that the ancestral pre-Brassicales genome had 9 or 14 chromosome pairs, later multiplied by the At-β (beta) whole-genome duplication (WGD) to n = 18 or 28. This WGD was followed by post-polyploid diploidization marked by diversification to 12 or 13 families and independent decreases in chromosome numbers. Family-specific WGDs are proposed to precede the diversification of Capparaceae, Resedaceae and Tropaeolaceae.