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Proc Natl Acad Sci U S A. 2017 Dec 5;114(49):E10550-E10559. doi: 10.1073/pnas.1716459114. Epub 2017 Nov 20.

Tracking the genome-wide outcomes of a transposable element burst over decades of amplification.

Author information

1
Department of Botany and Plant Sciences, University of California, Riverside CA 92521.
2
Institute for Integrative Genome Biology, University of California, Riverside, CA 92521.
3
Department of Microbiology and Plant Pathology, University of California, Riverside, CA 92521.
4
Graduate School of Agriculture, Kyoto University, Kitashirakawa-oiwake Sakyo, Kyoto 606-8502, Japan.
5
Department of Botany and Plant Sciences, University of California, Riverside CA 92521; susan.wessler@ucr.edu.

Abstract

To understand the success strategies of transposable elements (TEs) that attain high copy numbers, we analyzed two pairs of rice (Oryza sativa) strains, EG4/HEG4 and A119/A123, undergoing decades of rapid amplification (bursts) of the class 2 autonomous Ping element and the nonautonomous miniature inverted repeat transposable element (MITE) mPing Comparative analyses of whole-genome sequences of the two strain pairs validated that each pair has been maintained for decades as inbreds since divergence from their respective last common ancestor. Strains EG4 and HEG4 differ by fewer than 160 SNPs and a total of 264 new mPing insertions. Similarly, strains A119 and A123 exhibited about half as many SNPs (277) as new mPing insertions (518). Examination of all other potentially active TEs in these genomes revealed only a single new insertion out of ∼40,000 loci surveyed. The virtual absence of any new TE insertions in these strains outside the mPing bursts demonstrates that the Ping/mPing family gradually attains high copy numbers by maintaining activity and evading host detection for dozens of generations. Evasion is possible because host recognition of mPing sequences appears to have no impact on initiation or maintenance of the burst. Ping is actively transcribed, and both Ping and mPing can transpose despite methylation of terminal sequences. This finding suggests that an important feature of MITE success is that host recognition does not lead to the silencing of the source of transposase.

KEYWORDS:

MITE; genome evolution; mPing; rice; transposon silencing

PMID:
29158416
PMCID:
PMC5724284
DOI:
10.1073/pnas.1716459114
[Indexed for MEDLINE]
Free PMC Article

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