title: Copy number variation in transcriptionally active regions of sexual and apomictic Boechera demonstrates independently derived apomictic lineages.
abstract: In asexual (apomictic) plants, the absence of meiosis and sex is expected to lead to mutation accumulation. To compare mutation accumulation in the transcribed genomic regions of sexual and apomictic plants, we performed a double-validated analysis of copy number variation (CNV) on 10 biological replicates each of diploid sexual and diploid apomictic Boechera, using a high-density (>700 K) custom microarray. The Boechera genome demonstrated higher levels of depleted CNV, compared with enriched CNV, irrespective of reproductive mode. Genome-wide patterns of CNV revealed four divergent lineages, three of which contain both sexual and apomictic genotypes. Hence genome-wide CNV reflects at least three independent origins (i.e., expression) of apomixis from different sexual genetic backgrounds. CNV distributions for different families of transposable elements were lineage specific, and the enrichment of LINE/L1 and long term repeat/Copia elements in lineage 3 apomicts is consistent with sex and meiosis being mechanisms for purging genomic parasites. We hypothesize that significant overrepresentation of specific gene ontology classes (e.g., pollen-pistil interaction) in apomicts implies that gene enrichment could be an adaptive mechanism for genome stability in diploid apomicts by providing a polyploid-like system for buffering the effects of deleterious mutations.
authors.affiliation: Apomixis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany.
authors.forename: Olawale M
authors.initials: OM
authors.lastname: Aliyu
authors.forename: Michael
authors.initials: M
authors.lastname: Seifert
authors.forename: José M
authors.initials: JM
authors.lastname: Corral
authors.forename: Joerg
authors.initials: J
authors.lastname: Fuchs
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Sharbel
mesh_terms: D019607:Brassicaceae / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D056915:DNA Copy Number Variations; D004171:Diploidy; D019143:Evolution, Molecular; D018745:Genome, Plant; D005838:Genotype; D009154:Mutation; D012100:Reproduction, Asexual