title: Dissecting a hidden gene duplication: the Arabidopsis thaliana SEC10 locus.
abstract: Repetitive sequences present a challenge for genome sequence assembly, and highly similar segmental duplications may disappear from assembled genome sequences. Having found a surprising lack of observable phenotypic deviations and non-Mendelian segregation in Arabidopsis thaliana mutants in SEC10, a gene encoding a core subunit of the exocyst tethering complex, we examined whether this could be explained by a hidden gene duplication. Re-sequencing and manual assembly of the Arabidopsis thaliana SEC10 (At5g12370) locus revealed that this locus, comprising a single gene in the reference genome assembly, indeed contains two paralogous genes in tandem, SEC10a and SEC10b, and that a sequence segment of 7 kb in length is missing from the reference genome sequence. Differences between the two paralogs are concentrated in non-coding regions, while the predicted protein sequences exhibit 99% identity, differing only by substitution of five amino acid residues and an indel of four residues. Both SEC10 genes are expressed, although varying transcript levels suggest differential regulation. Homozygous T-DNA insertion mutants in either paralog exhibit a wild-type phenotype, consistent with proposed extensive functional redundancy of the two genes. By these observations we demonstrate that recently duplicated genes may remain hidden even in well-characterized genomes, such as that of A. thaliana. Moreover, we show that the use of the existing A. thaliana reference genome sequence as a guide for sequence assembly of new Arabidopsis accessions or related species has at least in some cases led to error propagation.
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic; Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
authors.forename: Nemanja
authors.initials: N
authors.lastname: Vukašinović
authors.affiliation: Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
authors.forename: Fatima
authors.initials: F
authors.lastname: Cvrčková
authors.affiliation: Department of Botany, Faculty of Science, Charles University in Prague, Prague, Czech Republic; Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
authors.forename: Marek
authors.initials: M
authors.lastname: Eliáš
authors.affiliation: Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America.
authors.forename: Rex
authors.initials: R
authors.lastname: Cole
authors.affiliation: Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, Oregon, United States of America.
authors.forename: John E
authors.initials: JE
authors.lastname: Fowler
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic; Department of Experimental Plant Biology, Faculty of Science, Charles University in Prague, Prague, Czech Republic.
authors.forename: Viktor
authors.initials: V
authors.lastname: Žárský
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
authors.forename: Lukáš
authors.initials: L
authors.lastname: Synek
mesh_terms: D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D020440:Gene Duplication / Q000235:genetics*; D016254:Mutagenesis, Insertional / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D004269:DNA, Bacterial; C036483:T-DNA
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