title: Genomics of homoploid hybrid speciation: diversity and transcriptional activity of long terminal repeat retrotransposons in hybrid sunflowers.
abstract: Hybridization is thought to play an important role in plant evolution by introducing novel genetic combinations and promoting genome restructuring. However, surprisingly little is known about the impact of hybridization on transposable element (TE) proliferation and the genomic response to TE activity. In this paper, we first review the mechanisms by which homoploid hybrid species may arise in nature. We then present hybrid sunflowers as a case study to examine transcriptional activity of long terminal repeat retrotransposons in the annual sunflowers Helianthus annuus, Helianthus petiolaris and their homoploid hybrid derivatives (H. paradoxus, H. anomalus and H. deserticola) using high-throughput transcriptome sequencing technologies (RNAseq). Sampling homoploid hybrid sunflower taxa revealed abundant variation in TE transcript accumulation. In addition, genetic diversity for several candidate genes hypothesized to regulate TE activity was characterized. Specifically, we highlight one candidate chromatin remodelling factor gene with a direct role in repressing TE activity in a hybrid species. This paper shows that TE amplification in hybrid lineages is more idiosyncratic than previously believed and provides a first step towards identifying the mechanisms responsible for regulating and repressing TE expansions.
authors: Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 sebastien.renaut@gmail.com.
authors: Sebastien
authors: S
authors: Renaut
authors: Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
authors: Heather C
authors: HC
authors: Rowe
authors: Division of Biology, Kansas State University, 426 Ackert Hall, Manhattan, KS 66506, USA.
authors: Mark C
authors: MC
authors: Ungerer
authors: Biodiversity Research Centre and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4 Department of Biology, Indiana University, 1001 East Third St., Bloomington, IN 47405, USA.
authors: Loren H
authors: LH
authors: Rieseberg
mesh_terms: D001483:Base Sequence; D019295:Computational Biology; D049810:Genetic Speciation; D014644:Genetic Variation / Q000235:genetics*; D005828:Genetics, Population; D005838:Genotype; D006368:Helianthus / Q000235:genetics*; D006824:Hybridization, Genetic / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D018626:Retroelements / Q000235:genetics; D016415:Sequence Alignment; D020079:Terminal Repeat Sequences / Q000235:genetics
chemical_list: D018626:Retroelements
keywords: Helianthus; RNAseq; genome evolution; hybridization; transposable elements