title: Transcriptionally active heterochromatin in rye B chromosomes.
abstract: B chromosomes (Bs) are dispensable components of the genomes of numerous species. Thus far, there is a lack of evidence for any transcripts of Bs in plants, with the exception of some rDNA sequences. Here, we show that the Giemsa banding-positive heterochromatic subterminal domain of rye (Secale cereale) Bs undergoes decondensation during interphase. Contrary to the heterochromatic regions of A chromosomes, this domain is simultaneously marked by trimethylated H3K4 and by trimethylated H3K27, an unusual combination of apparently conflicting histone modifications. Notably, both types of B-specific high copy repeat families (E3900 and D1100) of the subterminal domain are transcriptionally active, although with different tissue type-dependent activity. No small RNAs were detected specifically for the presence of Bs. The lack of any significant open reading frame and the highly heterogeneous size of mainly polyadenylated transcripts indicate that the noncoding RNA may function as structural or catalytic RNA.
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben, Germany.
authors.forename: Mariana
authors.initials: M
authors.lastname: Carchilan
authors.forename: Margarida
authors.initials: M
authors.lastname: Delgado
authors.forename: Teresa
authors.initials: T
authors.lastname: Ribeiro
authors.forename: Pedro
authors.initials: P
authors.lastname: Costa-Nunes
authors.forename: Ana
authors.initials: A
authors.lastname: Caperta
authors.forename: Leonor
authors.initials: L
authors.lastname: Morais-Cecílio
authors.forename: R Neil
authors.initials: RN
authors.lastname: Jones
authors.forename: Wanda
authors.initials: W
authors.lastname: Viegas
authors.forename: Andreas
authors.initials: A
authors.lastname: Houben
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D032461:Chromosomes, Plant / Q000235:genetics*; D018744:DNA, Plant / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D018745:Genome, Plant; D006570:Heterochromatin / Q000235:genetics*; D006657:Histones / Q000378:metabolism; D007399:Interphase; D008239:Lysine / Q000378:metabolism; D008745:Methylation; D008969:Molecular Sequence Data; D009928:Organ Specificity; D026723:Polyadenylation; D012091:Repetitive Sequences, Nucleic Acid; D012434:Secale / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D014158:Transcription, Genetic
chemical_list: D018744:DNA, Plant; D006570:Heterochromatin; D006657:Histones; D008239:Lysine