Genome invasion by a hypomethylated satellite repeat in Australian crucifer Ballantinia antipoda. (28th June 2019)

• Record Type: Journal Article
• Authors: Finke, Andreas; Mandáková, Terezie; Nawaz, Kashif; Vu, Giang T. H.; Novák, Petr; Macas, Jiri; Lysak, Martin A.; Pecinka, Ales
• Is Part Of: Plant journal. Volume 99:Number 6(2019)
• Page Start: 1066
• Page End: 1079
• Publication Date: 2019-06-28
• Subjects: satellite repeats -- heterochromatin -- DNA methylation -- comparative genomics -- Brassicaceae; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.14380
• Languages: English
• ISSNs: 0960-7412

Abstract

Significance Statement: Most repetitive sequences in plant DNA are hypermethylated. We identified a satellite repeat that occupies over 10% of the nuclear genome in the Australian crucifer species Ballantinia antipoda in which most of its copies were DNA hypomethylated. Summary: Repetitive sequences are ubiquitous components of all eukaryotic genomes. They contribute to genome evolution and the regulation of gene transcription. However, the uncontrolled activity of repetitive sequences can negatively affect genome functions and stability. Therefore, repetitive DNAs are embedded in a highly repressive heterochromatic environment in plant cell nuclei. Here, we analyzed the sequence, composition and the epigenetic makeup of peculiar non‐pericentromeric heterochromatic segments in the genome of the Australian crucifer Ballantinia antipoda . By the combination of high throughput sequencing, graph‐based clustering and cytogenetics, we found that the heterochromatic segments consist of a mixture of unique sequences and an A−T‐rich 174 bp satellite repeat ( BaSAT1 ). BaSAT1 occupies about 10% of the B. antipoda nuclear genome in >250 000 copies. Unlike many other highly repetitive sequences, BaSAT1 repeats are hypomethylated; this contrasts with the normal patterns of DNA methylation in the B. antipoda genome. Detailed analysis of several copies revealed that these non‐methylated BaSAT1 repeats were also devoid of heterochromatic histone H3K9me2 methylation. However, the factors decisive for the methylation status of BaSAT1 repeats remain currently unknown. In summary, we show that even highly repetitive sequences can exist as hypomethylated in the plant nuclear genome.