title: Multiple horizontal transfers of nuclear ribosomal genes between phylogenetically distinct grass lineages.
abstract: The movement of nuclear DNA from one vascular plant species to another in the absence of fertilization is thought to be rare. Here, nonnative rRNA gene [ribosomal DNA (rDNA)] copies were identified in a set of 16 diploid barley (Hordeum) species; their origin was traceable via their internal transcribed spacer (ITS) sequence to five distinct Panicoideae genera, a lineage that split from the Pooideae about 60 Mya. Phylogenetic, cytogenetic, and genomic analyses implied that the nonnative sequences were acquired between 1 and 5 Mya after a series of multiple events, with the result that some currentHordeumsp. individuals harbor up to five different panicoid rDNA units in addition to the nativeHordeumrDNA copies. There was no evidence that any of the nonnative rDNA units were transcribed; some showed indications of having been silenced via pseudogenization. A single copy of aPanicumsp. rDNA unit present inH. bogdaniihad been interrupted by a native transposable element and was surrounded by about 70 kbp of mostly noncoding sequence of panicoid origin. The data suggest that horizontal gene transfer between vascular plants is not a rare event, that it is not necessarily restricted to one or a few genes only, and that it can be selectively neutral.
authors.affiliation: Institute of Botany, The Czech Academy of Sciences, Průhonice 25243, Czech Republic; vaclav.mahelka@ibot.cas.cz.
authors.forename: Václav
authors.initials: V
authors.lastname: Mahelka
authors.affiliation: Institute of Botany, The Czech Academy of Sciences, Průhonice 25243, Czech Republic.|Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Prague 6 16500, Czech Republic.
authors.forename: Karol
authors.initials: K
authors.lastname: Krak
authors.affiliation: Institute of Experimental Botany, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc 78371, Czech Republic.
authors.forename: David
authors.initials: D
authors.lastname: Kopecký
authors.affiliation: Institute of Botany, The Czech Academy of Sciences, Průhonice 25243, Czech Republic.
authors.forename: Judith
authors.initials: J
authors.lastname: Fehrer
authors.affiliation: Institute of Experimental Botany, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc 78371, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Šafář
authors.affiliation: Institute of Experimental Botany, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc 78371, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Bartoš
authors.affiliation: Institute of Experimental Botany, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc 78371, Czech Republic.|Institute of Biophysics, The Czech Academy of Sciences, Brno 61265, Czech Republic.
authors.forename: Roman
authors.initials: R
authors.lastname: Hobza
authors.affiliation: Institute of Experimental Botany, Centre of the Region Haná for Biotechnological and Agricultural Research, Olomouc 78371, Czech Republic.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Blavet
authors.affiliation: Experimental Taxonomy, Leibniz Institute of Plant Genetics and Crop Plant Research, D-06466 Gatersleben, Germany.|German Centre of Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany.
authors.forename: Frank R
authors.initials: FR
authors.lastname: Blattner
mesh_terms: D002467:Cell Nucleus / Q000235:genetics*; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics*; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D004171:Diploidy; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D017343:Genes, Plant / Q000235:genetics; D001467:Hordeum / Q000145:classification / Q000235:genetics; D010802:Phylogeny; D006109:Poaceae / Q000145:classification / Q000235:genetics*; D017422:Sequence Analysis, DNA
chemical_list: D018744:DNA, Plant; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer
keywords: Hordeum; Panicoideae; Triticeae; horizontal gene transfer; transposable elements