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Ectopic Expression of a Maize Gene Is Induced by Composite Insertions Generated Through Alternative Transposition.

Authors
  • Su, Weijia1
  • Zuo, Tao1
  • Peterson, Thomas2, 3
  • 1 Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011-3260.
  • 2 Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011-3260 [email protected]
  • 3 Department of Agronomy, Iowa State University, Ames, Iowa 50011-3260.
Type
Published Article
Journal
Genetics
Publisher
The Genetics Society of America
Publication Date
Dec 01, 2020
Volume
216
Issue
4
Pages
1039–1049
Identifiers
DOI: 10.1534/genetics.120.303592
PMID: 32988986
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Transposable elements (TEs) are DNA sequences that can mobilize and proliferate throughout eukaryotic genomes. Previous studies have shown that in plant genomes, TEs can influence gene expression in various ways, such as inserting in introns or exons to alter transcript structure and content, and providing novel promoters and regulatory elements to generate new regulatory patterns. Furthermore, TEs can also regulate gene expression at the epigenetic level by modifying chromatin structure, changing DNA methylation status, and generating small RNAs. In this study, we demonstrated that Ac/fractured Ac (fAc) TEs are able to induce ectopic gene expression by duplicating and shuffling enhancer elements. Ac/fAc elements belong to the hAT family of class II TEs. They can undergo standard transposition events, which involve the two termini of a single transposon, or alternative transposition events that involve the termini of two different nearby elements. Our previous studies have shown that alternative transposition can generate various genome rearrangements such as deletions, duplications, inversions, translocations, and composite insertions (CIs). We identified >50 independent cases of CIs generated by Ac/fAc alternative transposition and analyzed 10 of them in detail. We show that these CIs induced ectopic expression of the maize pericarp color 2 (p2) gene, which encodes a Myb-related protein. All the CIs analyzed contain sequences including a transcriptional enhancer derived from the nearby p1 gene, suggesting that the CI-induced activation of p2 is affected by mobilization of the p1 enhancer. This is further supported by analysis of a mutant in which the CI is excised and p2 expression is lost. These results show that alternative transposition events are not only able to induce genome rearrangements, but also generate CIs that can control gene expression. Copyright © 2020 by the Genetics Society of America.

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