title: Identification and molecular characterization of the nicotianamine synthase gene family in bread wheat.
abstract: Nicotianamine (NA) is a non-protein amino acid involved in fundamental aspects of metal uptake, transport and homeostasis in all plants and constitutes the biosynthetic precursor of mugineic acid family phytosiderophores (MAs) in graminaceous plant species. Nicotianamine synthase (NAS) genes, which encode enzymes that synthesize NA from S-adenosyl-L-methionine (SAM), are differentially regulated by iron (Fe) status in most plant species and plant genomes have been found to contain anywhere from 1 to 9 NAS genes. This study describes the identification of 21 NAS genes in the hexaploid bread wheat (Triticum aestivum L.) genome and their phylogenetic classification into two distinct clades. The TaNAS genes are highly expressed during germination, seedling growth and reproductive development. Fourteen of the clade I NAS genes were up-regulated in root tissues under conditions of Fe deficiency. Protein sequence analyses revealed the presence of endocytosis motifs in all of the wheat NAS proteins as well as chloroplast, mitochondrial and secretory transit peptide signals in four proteins. These results greatly expand our knowledge of NAS gene families in graminaceous plant species as well as the genetics underlying Fe nutrition in bread wheat.
authors.affiliation: School of BioSciences, The University of Melbourne, Melbourne, Vic., Australia.
authors.forename: Julien
authors.initials: J
authors.lastname: Bonneau
authors.affiliation: Australian Centre for Plant Functional Genomics, The University of Adelaide, Adelaide, SA, Australia.
authors.forename: Ute
authors.initials: U
authors.lastname: Baumann
authors.affiliation: School of BioSciences, The University of Melbourne, Melbourne, Vic., Australia.
authors.forename: Jesse
authors.initials: J
authors.lastname: Beasley
authors.affiliation: Australian Centre for Plant Functional Genomics, The University of Adelaide, Adelaide, SA, Australia.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of BioSciences, The University of Melbourne, Melbourne, Vic., Australia.
authors.forename: Alexander A T
authors.initials: AA
authors.lastname: Johnson
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D007501:Iron / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D014908:Triticum / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D007501:Iron; D019883:Alkyl and Aryl Transferases; C118230:nicotianamine synthase
keywords: 
  Triticum aestivum
  ; gene expression; ion transport; iron; nutrient and metal transport; phytosiderophore