title: Genome evolution of wild barley (Hordeum spontaneum) by BARE-1 retrotransposon dynamics in response to sharp microclimatic divergence.
abstract: The replicative spread of retrotransposons in the genome creates new insertional polymorphisms, increasing retrotransposon numbers and potentially both their share of the genome and genome size. The BARE-1 retrotransposon constitutes a major, dispersed, active component of Hordeum genomes, and BARE-1 number is positively correlated with genome size. We have examined genome size and BARE-1 insertion patterns and number in wild barley, Hordeum spontaneum, in Evolution Canyon, Lower Nahal Oren, Mount Carmel, Israel, along a transect presenting sharply differing microclimates. BARE-1 has been sufficiently active for its insertional pattern to resolve individuals in a way consonant with their ecogeographical distribution in the canyon and to distinguish them from provenances outside the canyon. On both slopes, but especially on the drier south-facing slope, a simultaneous increase in the BARE-1 copy number and a decrease in the relative number lost through recombination, as measured by the abundance of solo long terminal repeats, appear to have driven the BARE-1 share of the genome upward with the height and dryness of the slope. The lower recombinational loss would favor maintenance of more full-length copies, enhancing the ability of the BARE-1 family to contribute to genome size growth. These local data are consistent with regional trends for BARE-1 in H. spontaneum across Israel and therefore may reflect adaptive selection for increasing genome size through retrotransposon activity.
authors.affiliation: Institute of Biotechnology, University of Helsinki, Plant Genomics Laboratory, Viikki Biocenter, P.O. Box 56, FIN-00014 Helsinki, Finland.
authors.forename: R
authors.initials: R
authors.lastname: Kalendar
authors.forename: J
authors.initials: J
authors.lastname: Tanskanen
authors.forename: S
authors.initials: S
authors.lastname: Immonen
authors.forename: E
authors.initials: E
authors.lastname: Nevo
authors.forename: A H
authors.initials: AH
authors.lastname: Schulman
mesh_terms: D005075:Biological Evolution; D005434:Flow Cytometry; D018628:Gene Dosage; D017343:Genes, Plant; D001467:Hordeum / Q000235:genetics*; D018626:Retroelements; D020079:Terminal Repeat Sequences
chemical_list: D018626:Retroelements