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The genomic organization of Ty3 / gypsy ‐like retrotransposons in Helianthus (Asteraceae) homoploid hybrid species
Author(s) -
Staton S. Evan,
Ungerer Mark C.,
Moore Richard C.
Publication year - 2009
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.0800337
Subject(s) - biology , retrotransposon , helianthus , hybrid , helianthus annuus , sunflower , introgression , evolutionary biology , botany , genetics , transposable element , genome , gene , horticulture
The origin of new diploid, or homoploid, hybrid species is associated with rapid genomic restructuring in the hybrid neospecies. This mode of speciation has been best characterized in wild sunflower species in the genus Helianthus , where three homoploid hybrid species ( H. anomalus, H. deserticola , and H. paradoxus ) have independently arisen via ancient hybridization events between the same two parental species ( H. annuus and H. petiolaris ). Most previous work examining genomic restructuring in these sunflower hybrid species has focused on chromosomal rearrangements. However, the origin of all three homoploid hybrid sunflower species also is associated with massive proliferation events of Ty3/gypsy ‐like retrotransposons in the hybrid species’ genomes. We compared the genomic organization of these elements in the parent species and two of the homoploid hybrid species using fluorescence in situ hybridization (FISH). We found a significant expansion of Ty3/gypsy ‐like retrotransposons confined to the pericentromeric regions of two hybrid sunflower species, H. deserticola and H. paradoxus . In contrast, we detected no significant increase in the frequency or extent of dispersed retrotransposon populations in the hybrid species within the resolution limits of our assay. We discuss the potential role that transposable element proliferation and localization plays in the evolution of homoploid hybrid species.