Na⁺ transporter, TaHKT1;5‐D, limits shoot Na⁺ accumulation in bread wheat

• Published in: The Plant journal : for cell and molecular biology Vol. 80; no. 3; pp. 516 - 526
• Main Authors: Byrt, Caitlin Siobhan, Xu, Bo, Krishnan, Mahima, Lightfoot, Damien James, Athman, Asmini, Jacobs, Andrew Keith, Watson‐Haigh, Nathan S, Plett, Darren, Munns, Rana, Tester, Mark, Gilliham, Matthew
• Format: Journal Article
• Language: English
• Published: England Blackwell Scientific Publishers and BIOS Scientific Publishers in association with the Society for Experimental Biology 01.11.2014; Blackwell Publishing Ltd
• Subjects: Animals; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis thaliana; Base Sequence; Bread; Cation Transport Proteins - genetics; Cation Transport Proteins - metabolism; Crop science; DNA; Gene Expression; Gene Expression Regulation, Plant; Genes; genetically modified organisms; Genomics; HKT; Leaves; loci; mesophyll; Molecular Sequence Data; Oocytes; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - genetics; Plant Roots - metabolism; plasma membrane; polymerase chain reaction; potassium; protoplasts; RNA; RNA interference; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Salinity; Salinity tolerance; Salt tolerance; Sequence Analysis, DNA; shoots; sodium; Sodium - metabolism; sodium exclusion; stele; Symporters - genetics; Symporters - metabolism; Transgenes; Triticum - cytology; Triticum - genetics; Triticum - metabolism; Triticum aestivum; Wheat; Xenopus laevis; Xylem - metabolism; xylem vessels; HKT; salt tolerance; wheat; RNA interference; Triticum aestivum; sodium exclusion
• ISSN: 0960-7412; 1365-313X; 1365-313X
• DOI: 10.1111/tpj.12651

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.