Transposons: a blessing curse

Manu J Dubin,Ortrun Mittelsten Scheid,Claude Becker

doi:10.1016/j.pbi.2018.01.003

Abstract

The genomes of most plant species are dominated by transposable elements (TEs). Once considered as 'junk DNA', TEs are now known to have a major role in driving genome evolution. Over the last decade, it has become apparent that some stress conditions and other environmental stimuli can drive bursts of activity of certain TE families and consequently new TE insertions. These can give rise to altered gene expression patterns and phenotypes, with new TE insertions sometimes causing flanking genes to become transcriptionally responsive to the same stress conditions that activated the TE in the first place. Such connections between TE-mediated increases in diversity and an accelerated rate of genome evolution provide powerful mechanisms for plants to adapt more rapidly to new environmental conditions. This review will focus on environmentally induced transposition, the mechanisms by which it alters gene expression, and the consequences for plant genome evolution and breeding.

Highlights

Transposable elements (TEs) account for the largest fraction of historically called ‘junk DNA’, that is, DNA stretches without an obvious protein-coding or regulatory functional relevance for the organism
It is clear that TE-derived DNA sequences are not mere ‘junk DNA’ but play a fundamental role in regulating gene expression and are an important source of genetic variation in plants
This is highlighted by the massive changes in TE abundance and diversity that occurred during domestication [4] and as a result of breeding efforts [35,48]

Summary

Introduction

Transposable elements (TEs) account for the largest fraction of historically called ‘junk DNA’, that is, DNA stretches without an obvious protein-coding or regulatory functional relevance for the organism. As their name suggests, TEs are mobile within the genome. The accumulation of TEs in gene-poor heterochromatin like pericentromeric regions may be the result of efficient selection against active elements, but many TEs, non-autonomous DNA transposons, are frequent near (

24 Genome studies and molecular genetics

Conclusions and outlook

Arabidopsis Genome Initiative

12. Lisch D

Findings

36. Paszkowski J