Progressive refinement of the karyotyping of Brachypodium genomes

Abstract

Brachypodium distachyon is a weedy grass species that is firmly established as a model for the comparative and functional genomics of temperate cereals and grasses. Its simple, nuclear genome of five chromosomes contrasts it with other relatives of the genus with different, and usually higher, basic chromosome numbers and ploidy levels. This variation in karyotypic structure affords the possibility of reconstructing evolutionary pathways that have shaped the genome structure of extant species. This Tansley insight documents how key refinements in molecular cytogenetic approaches, from simple fluorescence in situ hybridization to comparative chromosome barcoding, have enabled genome structure studies and yielded valuable information about the drivers of karyotypic reorganization and evolution in the model grass genus Brachypodium.

Keywords: Brachypodium; chromosome specific probes; dysploidy; fluorescence in situ hybridization; karyotype structure and evolution; model grass; molecular cytogenetics; polyploidy.