title: An integrated approach for the comparative analysis of a multigene family: the nicotianamine synthase genes of barley.
abstract: Recent genomic projects reveal that about half of the gene repertoire in plant genomes is made up by multigene families. In this paper, a set of structural and phylogenetic analyses have been applied to compare the differently sized nicotianamine synthase (NAS) gene families in barley and rice. Nicotianamine acts as a chelator of iron and other heavy metals and plays a key role in uptake, phloem transport and cytoplasmic distribution of iron, challenging efforts for the breeding of iron-efficient crop plants. Nine barley NAS genes have been mapped, and co-linearity of flanking genes in barley and rice was determined. The combined analyses reveal that the NAS multigene family members in barley originated through at least one duplication event that occurred before the divergence of rice and barley. Additional duplications appear to have occurred within each of the species. Although we detected no evidence for positive selection of recently duplicated genes within species, codon-based tests revealed evidence for positive selection having contributed to the divergence of some amino acids. The integrated comparative and phylogenetic analysis improved our current view of NAS gene family evolution, might facilitate the functional characterization of individual members and is applicable to other multigene families.
authors.affiliation: Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Gatersleben, Germany.
authors.forename: Dragan
authors.initials: D
authors.lastname: Perovic
authors.forename: Peter
authors.initials: P
authors.lastname: Tiffin
authors.forename: Dimitar
authors.initials: D
authors.lastname: Douchkov
authors.forename: Helmut
authors.initials: H
authors.lastname: Bäumlein
authors.forename: Andreas
authors.initials: A
authors.lastname: Graner
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics*; D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D023281:Genomics; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family
chemical_list: D019883:Alkyl and Aryl Transferases; C118230:nicotianamine synthase