EARE-1, a Transcriptionally Active Ty1/Copia-Like Retrotransposon Has Colonized the Genome of Excoecaria agallocha through Horizontal Transfer.

ABSTRACT: Long terminal repeat (LTR) retrotransposons constitute the majority of the content of angiosperm genomes, but their evolutionary dynamics remain poorly understood. Here, we report the isolation and characterization of a putative full-length (~9550 bp) Ty1/copia-like retrotransposon in Excoecaria agallocha and its evolution in Euphorbiaceae. The so-called EARE-1 is phylogenetically closely related to RIRE-1 from Oryza australiensis, and has proliferated recently (~7.19 Mya) in the E. agallocha genome. An RT-PCR analysis revealed substantial transcription of EARE-1 in all examined organs (leaves, staminate flowers, pistillate flowers, seeds, and roots) in unstressed E. agallocha plants and indications of elevated expression under stress. We conducted sequence analyses of 256 RT-RH fragments (~860 bp) of EARE-1 from 34 species representing four subfamilies of Euphorbiaceae that exist in China. EARE-1 copies from two Excoecaria species and Phyllanthus urinaria showed incongruent phylogeny with the host species and exhibited high sequence similarity to the host genes, suggesting a horizontal transfer from P. urinaria to the common ancestor of Excoecaria. However, SSAP analysis detected no new insertions of EARE-1 among full-sibling progeny plants of E. agallocha, despite considerable SSAP polymorphisms among half-siblings. EARE-1 is the first transcriptionally active Ty1/copia-like retrotransposon isolated from E. agallocha. Our results provide empirical evidence of the horizontal transfer of LTR retrotransposons in plants, and may suggest a significant role of post-transcriptional host control in the life cycles of transposable elements.

SUBMITTER: Huang J 

PROVIDER: S-EPMC5258746 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature