title: Identification and characterization of zinc-starvation-induced ZIP transporters from barley roots.
abstract: Zinc (Zn) is an essential element for plants but limited information is currently available on the molecular basis for Zn(2+) transport in crop species. To expand the knowledge on Zn(2+) transport in barley (Hordeum vulgare L.), a cDNA library prepared from barley roots was expressed in the yeast (Saccharomyces cerevisiae) mutant strain Deltazrt1/Deltazrt2, defective in Zn(2+) uptake. This strategy resulted in isolation and identification of three new Zn(2+) transporters from barley. All of the predicted proteins have a high similarity to the ZIP protein family, and are designated HvZIP3, HvZIP5 and HvZIP8, respectively. Complementation studies in Deltazrt1/Deltazrt2 showed restored growth of the yeast cells transformed with the different HvZIPs, although with different efficiency. Transformation into Fe(2+) and Mn(2+) uptake defective yeast mutants showed that the HvZIPs were unable to restore the growth on Fe(2+) and Mn(2+) limited media, respectively, indicating a specific role in Zn(2+) transport. In intact barley roots, HvZIP8 was constitutively expressed whereas HvZIP3 and HvZIP5 were mainly expressed in -Zn plants. These results suggest that HvZIP3, HvZIP5 and HvZIP8 are Zn(2+) transporters involved in Zn(2+) homeostasis in barley roots. The new transporters may facilitate breeding of barley genotypes with improved Zn efficiency and Zn content.
authors.affiliation: Department of Agriculture and Ecology, University of Copenhagen, Denmark. pp@life.ku.dk
authors.forename: Pai
authors.initials: P
authors.lastname: Pedas
authors.forename: Jan K
authors.initials: JK
authors.lastname: Schjoerring
authors.forename: Søren
authors.initials: S
authors.lastname: Husted
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D001467:Hordeum / Q000235:genetics* / Q000378:metabolism; D017136:Ion Transport; D007501:Iron / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D027682:Cation Transport Proteins; D010940:Plant Proteins; C017800:zinc-binding protein; D008345:Manganese; D007501:Iron; D015032:Zinc