Recent retrotransposon insertions are methylated and phylogenetically clustered in japonica rice (Oryza sativa spp. japonica)

Bridgett Marie vonHoldt, Shohei Takuno, Brandon S. Gaut

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

In plants, the genome of the host responds to the amplification of transposable elements (TEs) with DNA methylation. However, neither the factors involved in TE methylation nor the dynamics of the host-TE interaction are well resolved. Here, we identify 5,522 long terminal repeat retrotransposons (LTR-RT) in the genome of Oryza sativa ssp. japonica and then assess methylation for individual elements. Our analyses uncover three strong trends: long LTR-RTs are more highly methylated, the insertion times of LTR-RTs are negatively correlated with methylation, and young LTR-RTs tend to be closer to genes than older insertions. Additionally, a phylogenetic examination of the gypsy-like LTR-RT superfamily revealed that methylation is phylogenetically correlated. Given these observations, we present a model suggesting that the phylogenetic correlation among related LTR-RTs is a primary mechanism driving methylation. In this model, bursts of transposition produce new elements with high sequence similarity. The host machinery identifies proliferating elements as well as closely related LTR-RTs through cross-homology. In addition, our data are consistent with previous hypotheses that methylated LTR-RT elements are removed preferentially from regions near genes, explaining some of the observed age distribution.

Original languageEnglish (US)
Pages (from-to)3193-3203
Number of pages11
JournalMolecular biology and evolution
Volume29
Issue number10
DOIs
StatePublished - Oct 1 2012

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics
  • Molecular Biology
  • Genetics

Keywords

  • LTR retrotransposons
  • japonica rice
  • methylation
  • phylogenetic signal

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