title: Arabidopsis thaliana nicotianamine synthase 4 is required for proper response to iron deficiency and to cadmium exposure.
abstract: The nicotianamine synthase (NAS) enzymes catalyze the formation of nicotianamine (NA), a non-proteinogenic amino acid involved in iron homeostasis. We undertook the functional characterization of AtNAS4, the fourth member of the Arabidopsis thaliana NAS gene family. A mutant carrying a T-DNA insertion in AtNAS4 (atnas4), as well as lines overexpressing AtNAS4 both in the atnas4 and the wild-type genetic backgrounds, were used to decipher the role of AtNAS4 in NA synthesis, iron homeostasis and the plant response to iron deficiency or cadmium supply. We showed that AtNAS4 is an important source for NA. Whereas atnas4 had normal growth in iron-sufficient medium, it displayed a reduced accumulation of ferritins and exhibited a hypersensitivity to iron deficiency. This phenotype was rescued in the complemented lines. Under iron deficiency, atnas4 displayed a lower expression of the iron uptake-related genes IRT1 and FRO2 as well as a reduced ferric reductase activity. Atnas4 plants also showed an enhanced sensitivity to cadmium while the transgenic plants overexpressing AtNAS4 were more tolerant. Collectively, our data, together with recent studies, support the hypothesis that AtNAS4 displays an important role in iron distribution and is required for proper response to iron deficiency and to cadmium supply.
authors.affiliation: UMR 1347 Agroécologie AgroSup Dijon/INRA/Université de Bourgogne, Pôle Mécanisme et Gestion des Interactions Plantes-microorganismes - ERL CNRS 6300, Dijon, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Koen
authors.forename: Angélique
authors.initials: A
authors.lastname: Besson-Bard
authors.forename: Céline
authors.initials: C
authors.lastname: Duc
authors.forename: Jérémy
authors.initials: J
authors.lastname: Astier
authors.forename: Antoine
authors.initials: A
authors.lastname: Gravot
authors.forename: Pierre
authors.initials: P
authors.lastname: Richaud
authors.forename: Olivier
authors.initials: O
authors.lastname: Lamotte
authors.forename: Jossia
authors.initials: J
authors.lastname: Boucherez
authors.forename: Frédéric
authors.initials: F
authors.lastname: Gaymard
authors.forename: David
authors.initials: D
authors.lastname: Wendehenne
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001383:Azetidinecarboxylic Acid / Q000031:analogs & derivatives* / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D027682:Cation Transport Proteins / Q000378:metabolism; D004269:DNA, Bacterial; D038181:FMN Reductase / Q000378:metabolism; D005293:Ferritins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D006706:Homeostasis; D007501:Iron / Q000378:metabolism; D000090463:Iron Deficiencies; D009154:Mutation; D010641:Phenotype; D030821:Plants, Genetically Modified; D013312:Stress, Physiological / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; D004269:DNA, Bacterial; C099651:IRT1 protein, Arabidopsis; C036483:T-DNA; D002104:Cadmium; C082893:nicotianamine; D001383:Azetidinecarboxylic Acid; D005293:Ferritins; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase; D019883:Alkyl and Aryl Transferases; C585522:NAS4 protein, Arabidopsis