Histone modifications rather than the novel regional centromeres of Zymoseptoria tritici distinguish core and accessory chromosomes

作者：Klaas Schotanus, Jessica L. Soyer, Lanelle Connolly, Jonathan Grandaubert, Petra Happel, Kristina Smith, Michael Freitag, Eva H. Stukenbrock · 发表于：Epigenetics & Chromatin · 年份：2015 · DOI：10.1186/s13072-015-0033-5 · 被引用次数：204 · 研究领域：Chromosomal and Genetic Variations、Plant Molecular Biology Research、Genomics and Chromatin Dynamics

BACKGROUND: Supernumerary chromosomes have been found in many organisms. In fungi, these "accessory" or "dispensable" chromosomes are present at different frequencies in populations and are usually characterized by higher repetitive DNA content and lower gene density when compared to the core chromosomes. In the reference strain of the wheat pathogen, Zymoseptoria tritici, eight discrete accessory chromosomes have been found. So far, no functional role has been assigned to these chromosomes; however, they have existed as separate entities in the karyotypes of Zymoseptoria species over evolutionary time. In this study, we addressed what-if anything-distinguishes the chromatin of accessory chromosomes from core chromosomes. We used chromatin immunoprecipitation combined with high-throughput sequencing ("ChIP-seq") of DNA associated with the centromere-specific histone H3, CENP-A (CenH3), to identify centromeric DNA, and ChIP-seq with antibodies against dimethylated H3K4, trimethylated H3K9 and trimethylated H3K27 to determine the relative distribution and proportion of euchromatin, obligate and facultative heterochromatin, respectively. RESULTS: Centromeres of the eight accessory chromosomes have the same sequence composition and structure as centromeres of the 13 core chromosomes and they are of similar length. Unlike those of most other fungi, Z. tritici centromeres are not composed entirely of repetitive DNA; some centromeres contain only unique DNA sequences, and bona fide ...