Structural variations in wheat HKT1;5 underpin differences in Na+ transport capacity

Bo Xu, Shane Waters, Caitlin S. Byrt, Darren Plett, Stephen D. Tyerman, Mark A. Tester, Rana Munns, Maria Hrmova, Mathew Gilliham

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

An important trait associated with the salt tolerance of wheat is the exclusion of sodium ions (Na+) from the shoot. We have previously shown that the sodium transporters TmHKT1;5-A and TaHKT1;5-D, from Triticum monoccocum (Tm) and Triticum aestivum (Ta), are encoded by genes underlying the major shoot Na+-exclusion loci Nax1 and Kna1, respectively. Here, using heterologous expression, we show that the affinity (Km) for the Na+ transport of TmHKT1;5-A, at 2.66 mM, is higher than that of TaHKT1;5-D at 7.50 mM. Through 3D structural modelling, we identify residues D471/a gap and D474/G473 that contribute to this property. We identify four additional mutations in amino acid residues that inhibit the transport activity of TmHKT1;5-A, which are predicted to be the result of an occlusion of the pore. We propose that the underlying transport properties of TmHKT1;5-A and TaHKT1;5-D contribute to their unique ability to improve Na+ exclusion in wheat that leads to an improved salinity tolerance in the field.
Original languageEnglish (US)
Pages (from-to)1133-1144
Number of pages12
JournalCellular and Molecular Life Sciences
Volume75
Issue number6
DOIs
StatePublished - Nov 27 2017

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