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

C.S. Byrt, B. Xu, M. Krishnan, D.J. Lightfoot, A. Athman, A.K. Jacobs, N.S. Watson-Haigh, D.C. Plett, Rana Munns, M. Tester, M. Gilliham

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Abstract

© 2014 The Authors. The Plant Journal © 2014 John Wiley & Sons Ltd. 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.
Original languageEnglish
Pages (from-to)516-526
Number of pages11
JournalThe Plant Journal
Volume80
Issue number3
Early online date1 Oct 2014
DOIs
Publication statusPublished - 14 Oct 2014

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