Variability, recombination, and mosaic evolution of the barley BARE-1 retrotransposon

Carlos M. Vicient, Ruslan Kalendar, Alan H. Schulman

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)

Abstract

BARE-1 is a highly abundant, copia-like, LTR (long terminal repeat) retrotransposon in the genus Hordeum. The LTRs provide the promoter, terminator, and polyadenylation signals necessary for the replicational life cycle of retrotransposons. We have examined the variability and evolution of BARE-1-like elements, focusing on the LTRs. Three groups were found, corresponding to each of the Hordeum genome types analyzed, which predate the divergence of these types. The most variable LTR regions are tandem repeats near the 3′ end and the promoter. In barley (H. vulgare L.), two main classes of LTR promoters were defined, corresponding to BARE-1 and to a new class we call BARE-2. These can be considered as families within the group I BARE elements. Although less abundant in cultivated barley than is BARE-1, BARE-2 is transcriptionally active in leaves and calli. A sequenced BARE-2 has more than 99% similar LTRs and perfect terminal direct repeats (TDRs), indicating it is a recent insertion, but the coding region, especially gag, is disrupted by frameshifts and stop codons. BARE-2 appears to be a chimeric element resulting from retrotransposon recombination by strand switching during replication, with LTRs and 5′UTR more similar to BARE-1 and the rest more similar to Wis-2. We provide evidence as well for another form of recombination, where LTR-LTR recombination has generated tandem multimeric BARE-1 elements in which internal coding domains are interspersed with shared LTRs. The data indicate that recombination contributes to the complexity and plasticity of retroelement evolution in plant genomes.

Original languageEnglish
Pages (from-to)275-291
Number of pages17
JournalJournal of Molecular Evolution
Volume61
Issue number3
DOIs
Publication statusPublished - Sep 2005
Externally publishedYes

Keywords

  • BARE-1 retrotransposon
  • Barley
  • DNA recombination
  • Hordeum vulgare L.
  • LTR promoter
  • Molecular evolution

ASJC Scopus subject areas

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

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