Identification and molecular characterization of the nicotianamine synthase gene family in bread wheat

• Published in: Plant biotechnology journal Vol. 14; no. 12; pp. 2228 - 2239
• Main Authors: Bonneau, Julien, Baumann, Ute, Beasley, Jesse, Li, Yuan, Johnson, Alexander A. T.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01-12-2016; John Wiley and Sons Inc
• Subjects: Alkyl and Aryl Transferases - genetics; Alkyl and Aryl Transferases - metabolism; Amino acid sequence; Amino acids; Barley; Biosynthesis; Bread; Chloroplasts; Chromosomes; Deoxyribonucleic acid; DNA; Efficiency; Endocytosis; Enzymes; Flowers & plants; Gene expression; Gene Expression Regulation, Plant - genetics; Gene Expression Regulation, Plant - physiology; Gene families; Genes; Genetic aspects; Genetics; Genomes; Genomics; Germination; Homeostasis; ion transport; Iron; Iron - metabolism; Iron deficiency; Metals; Methionine; Mitochondria; NAS gene; Nicotianamine synthase; nutrient and metal transport; Nutrition; Phylogeny; phytosiderophore; Plant genetics; Plant Proteins - genetics; Plant Proteins - metabolism; Plant species; Plant tissues; Plants (botany); Protein deficiency; Proteins; Seedlings; Species; Triticum - enzymology; Triticum - genetics; Triticum - metabolism; Triticum aestivum; Wheat; iron; ion transport; nutrient and metal transport; phytosiderophore; Triticum aestivum; gene expression
• ISSN: 1467-7644; 1467-7652
• DOI: 10.1111/pbi.12577

Summary
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.