title: Natural variation at the FRD3 MATE transporter locus reveals cross-talk between Fe homeostasis and Zn tolerance in Arabidopsis thaliana.
abstract: Zinc (Zn) is essential for the optimal growth of plants but is toxic if present in excess, so Zn homeostasis needs to be finely tuned. Understanding Zn homeostasis mechanisms in plants will help in the development of innovative approaches for the phytoremediation of Zn-contaminated sites. In this study, Zn tolerance quantitative trait loci (QTL) were identified by analyzing differences in the Bay-0 and Shahdara accessions of Arabidopsis thaliana. Fine-scale mapping showed that a variant of the Fe homeostasis-related FERRIC REDUCTASE DEFECTIVE3 (FRD3) gene, which encodes a multidrug and toxin efflux (MATE) transporter, is responsible for reduced Zn tolerance in A. thaliana. Allelic variation in FRD3 revealed which amino acids are necessary for FRD3 function. In addition, the results of allele-specific expression assays in F1 individuals provide evidence for the existence of at least one putative metal-responsive cis-regulatory element. Our results suggest that FRD3 works as a multimer and is involved in loading Zn into xylem. Cross-homeostasis between Fe and Zn therefore appears to be important for Zn tolerance in A. thaliana with FRD3 acting as an essential regulator.
authors.affiliation: CNRS-INRA-MontpellierSupAgro-UM2, UMR Biochimie et Physiologie Moléculaire des Plantes, Montpellier, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Pineau
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Loubet
authors.forename: Cécile
authors.initials: C
authors.lastname: Lefoulon
authors.forename: Claude
authors.initials: C
authors.lastname: Chalies
authors.forename: Cécile
authors.initials: C
authors.lastname: Fizames
authors.forename: Benoit
authors.initials: B
authors.lastname: Lacombe
authors.forename: Marina
authors.initials: M
authors.lastname: Ferrand
authors.forename: Olivier
authors.initials: O
authors.lastname: Loudet
authors.forename: Pierre
authors.initials: P
authors.lastname: Berthomieu
authors.forename: Odile
authors.initials: O
authors.lastname: Richard
mesh_terms: D000483:Alleles; D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D038181:FMN Reductase / Q000378:metabolism; D006706:Homeostasis / Q000235:genetics / Q000502:physiology; D007501:Iron / Q000378:metabolism / Q000502:physiology; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D040641:Quantitative Trait Loci / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D014118:Toxins, Biological / Q000235:genetics / Q000378:metabolism; D052584:Xylem / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000378:metabolism / Q000502:physiology
chemical_list: D029681:Arabidopsis Proteins; C469252:FRD3 protein, Arabidopsis; D026901:Membrane Transport Proteins; D014118:Toxins, Biological; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase; D015032:Zinc