title: The low-recombining pericentromeric region of barley restricts gene diversity and evolution but not gene expression.
abstract: The low-recombining pericentromeric region of the barley genome contains roughly a quarter of the genes of the species, embedded in low-recombining DNA that is rich in repeats and repressive chromatin signatures. We have investigated the effects of pericentromeric region residency upon the expression, diversity and evolution of these genes. We observe no significant difference in average transcript level or developmental RNA specificity between the barley pericentromeric region and the rest of the genome. In contrast, all of the evolutionary parameters studied here show evidence of compromised gene evolution in this region. First, genes within the pericentromeric region of wild barley show reduced diversity and significantly weakened purifying selection compared with the rest of the genome. Second, gene duplicates (ohnolog pairs) derived from the cereal whole-genome duplication event ca. 60MYa have been completely eliminated from the barley pericentromeric region. Third, local gene duplication in the pericentromeric region is reduced by 29% relative to the rest of the genome. Thus, the pericentromeric region of barley is a permissive environment for gene expression but has restricted gene evolution in a sizeable fraction of barley's genes.
authors.affiliation: University of Dundee at JHI, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Katie
authors.initials: K
authors.lastname: Baker
authors.forename: Micha
authors.initials: M
authors.lastname: Bayer
authors.forename: Nicola
authors.initials: N
authors.lastname: Cook
authors.forename: Steven
authors.initials: S
authors.lastname: Dreißig
authors.forename: Taniya
authors.initials: T
authors.lastname: Dhillon
authors.forename: Joanne
authors.initials: J
authors.lastname: Russell
authors.forename: Pete E
authors.initials: PE
authors.lastname: Hedley
authors.forename: Jenny
authors.initials: J
authors.lastname: Morris
authors.forename: Luke
authors.initials: L
authors.lastname: Ramsay
authors.forename: Isabelle
authors.initials: I
authors.lastname: Colas
authors.forename: Robbie
authors.initials: R
authors.lastname: Waugh
authors.forename: Brian
authors.initials: B
authors.lastname: Steffenson
authors.forename: Iain
authors.initials: I
authors.lastname: Milne
authors.forename: Gordon
authors.initials: G
authors.lastname: Stephen
authors.forename: David
authors.initials: D
authors.lastname: Marshall
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Flavell
mesh_terms: D001483:Base Sequence; D019143:Evolution, Molecular; D020440:Gene Duplication; D015870:Gene Expression; D063990:Gene Ontology; D014644:Genetic Variation; D018745:Genome, Plant / Q000235:genetics*; D006570:Heterochromatin / Q000235:genetics; D001467:Hordeum / Q000235:genetics*; D008969:Molecular Sequence Data; D011995:Recombination, Genetic; D017423:Sequence Analysis, RNA
chemical_list: D006570:Heterochromatin
keywords: Hordeum vulgare; barley; genome evolution; heterochromatin; pericentromeric