title: The Na(+) transporter, TaHKT1;5-D, limits shoot Na(+) accumulation in bread wheat.
abstract: Bread wheat (Triticum aestivum L.) has a major salt tolerance locus, Kna1, responsible for the maintenance of a high cytosolic K(+) /Na(+) ratio in the leaves of salt stressed plants. The Kna1 locus encompasses a large DNA fragment, the distal 14% of chromosome 4DL. Limited recombination has been observed at this locus making it difficult to map genetically and identify the causal gene. Here, we decipher the function of TaHKT1;5-D, a candidate gene underlying the Kna1 locus. Transport studies using the heterologous expression systems Saccharomyces cerevisiae and Xenopus laevis oocytes indicated that TaHKT1;5-D is a Na(+) -selective transporter. Transient expression in Arabidopsis thaliana mesophyll protoplasts and in situ polymerase chain reaction indicated that TaHKT1;5-D is localised on the plasma membrane in the wheat root stele. RNA interference-induced silencing decreased the expression of TaHKT1;5-D in transgenic bread wheat lines which led to an increase in the Na(+) concentration in the leaves. This indicates that TaHKT1;5-D retrieves Na(+) from the xylem vessels in the root and has an important role in restricting the transport of Na(+) from the root to the leaves in bread wheat. Thus, TaHKT1;5-D confers the essential salinity tolerance mechanism in bread wheat associated with the Kna1 locus via shoot Na(+) exclusion and is critical in maintaining a high K(+) /Na(+) ratio in the leaves. These findings show there is potential to increase the salinity tolerance of bread wheat by manipulation of HKT1;5 genes.
authors.affiliation: CSIRO Plant Industry, Canberra, ACT, 2601, Australia; School of Agriculture, Food and Wine and Waite Research Institute, University of Adelaide, Waite Research Precinct, Glen Osmond, SA, 5064, Australia; Australian Research Council Centre of Excellence in Plant Cell Walls, University of Adelaide, Waite Research Precinct, Glen Osmond, SA, 5064, Australia; Australian Centre for Plant Functional Genomics, University of Adelaide, Waite Research Precinct, Glen Osmond, SA, 5064, Australia; Australian Research Council Centre of Excellence in Plant Energy Biology, University of Adelaide, Waite Research Precinct, Glen Osmond, SA, 5064, Australia.
authors.forename: Caitlin Siobhan
authors.initials: CS
authors.lastname: Byrt
authors.forename: Bo
authors.initials: B
authors.lastname: Xu
authors.forename: Mahima
authors.initials: M
authors.lastname: Krishnan
authors.forename: Damien James
authors.initials: DJ
authors.lastname: Lightfoot
authors.forename: Asmini
authors.initials: A
authors.lastname: Athman
authors.forename: Andrew Keith
authors.initials: AK
authors.lastname: Jacobs
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Watson-Haigh
authors.forename: Darren
authors.initials: D
authors.lastname: Plett
authors.forename: Rana
authors.initials: R
authors.lastname: Munns
authors.forename: Mark
authors.initials: M
authors.lastname: Tester
authors.forename: Matthew
authors.initials: M
authors.lastname: Gilliham
mesh_terms: D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D027682:Cation Transport Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009865:Oocytes; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D055049:Salt Tolerance; D017422:Sequence Analysis, DNA; D012964:Sodium / Q000378:metabolism*; D027981:Symporters / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes; D014908:Triticum / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D014982:Xenopus laevis; D052584:Xylem / Q000378:metabolism
chemical_list: D027682:Cation Transport Proteins; C088864:HKT1 protein, plant; D010940:Plant Proteins; D027981:Symporters; D012964:Sodium
keywords: HKT; RNA interference; Triticum aestivum; salt tolerance; sodium exclusion; wheat