title: Arbuscular mycorrhizal colonization reduces arsenate uptake in barley via downregulation of transporters in the direct epidermal phosphate uptake pathway.
abstract: *Here, we used barley (Hordeum vulgare) grown in normal and compartmented pots to investigate sensitivity to arsenic (As) in the absence of a positive growth response to arbuscular mycorrhizas (AM). *We tested the hypothesis that upon inoculation with AM fungi downregulation of HvPht1;1 and HvPht1;2 genes (encoding high-affinity inorganic orthophosphate (P(i))-uptake systems in a direct pathway via root epidermis and root hairs) and upregulation of the AM-induced HvPht1;8 (encoding the P(i)-uptake system responsible for transfer of P(i) from the symbiotic interface to cortical cells) play a role in decreased As uptake and hence reduced As sensitivity in AM plants. *Barley did not respond, or responded negatively to colonization by Glomus intraradices in terms of growth. In terms of specific phosphorus (P) uptake (P uptake per g of root) barley was nonresponsive. There was a significant interaction between As treatment and colonization, resulting in a lower As concentration and uptake in AM compared with nonmycorrhizal (NM) plants. *The decreased uptake of As and higher P : As molar ratios in the AM barley can be explained by the operation of the AM pathway as indicated by induction of HvPht1;8 and by down-regulation of HvPht1;1 and HvPht1;2.
authors.affiliation: Soil and Land Systems, School of Environmental Sciences, The University of Adelaide, Adelaide, South Australia 5005, Australia. helle.christophersen@adelaide.edu.au
authors.forename: H M
authors.initials: HM
authors.lastname: Christophersen
authors.forename: F A
authors.initials: FA
authors.lastname: Smith
authors.forename: S E
authors.initials: SE
authors.lastname: Smith
mesh_terms: D001149:Arsenates / Q000378:metabolism*; D001151:Arsenic / Q000378:metabolism*; D001692:Biological Transport; D015536:Down-Regulation; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D055137:Glomeromycota; D001467:Hordeum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism; D053858:Metabolic Networks and Pathways / Q000502:physiology; D038821:Mycorrhizae / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism
chemical_list: D001149:Arsenates; D026901:Membrane Transport Proteins; D010710:Phosphates; D010758:Phosphorus; D001151:Arsenic; C025657:arsenic acid