Molecular Phylogenetics and Evolution, 2010, Vol.55(2), pp.650-659
Wall barley ( ) occurs with three subspecies, naturally distributed from southern Central Asia through the Mediterranean region to northwestern Europe, but now is an invasive weed in many parts of the world. Subspecies is diploid, while subspp. and are tetraploids, the latter also occurring with a hexaploid cytotype. Earlier analyses were inconclusive regarding auto- or allopolyploid origins of subspp. and . We analyzed the phylogeny of the taxon group using amplified fragment length polymorphisms (AFLP), sequences of cloned PCR products of the nuclear ribosomal DNA internal transcribed spacer region (ITS), a part of the nuclear single-copy gene topoisomerase 6 (Topo6) spanning two introns, and sequences of the chloroplast L-F region together with length variation at six chloroplast microsatellite loci, including multiple individuals of each subspecies and cytotype, covering the entire natural distribution area of the species. Phylogenetic analyses with all used markers differentiate diploid and polyploids. Sequences of both nuclear regions indicated that diploid subsp. was involved in tetraploid formation together with a now extinct species belonging to the same genome group (Xu). Furthermore, AFLP and ITS analyses suggest that a third, though closely related extinct taxon contributed to hexaploid formation. No method was able to discern tetraploid subspp. and , which we attribute to the young age of subsp. . None of the used molecular markers revealed a strong geographic pattern of genetic variation that would allow comprehensive phylogeographic analysis, most probably due to the very effective seed dispersal of the taxa.
Aflp ; Allopolyploidy ; Chloroplast Trnl-F ; Evolution ; Hordeum Murinum ; Nrdna Internal Transcribed Spacer (Its) ; Phylogeography ; Polyploid Evolution ; Topoisomerase 6 (Topo6) ; Biology
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