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

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.

Byrt CS ，Xu B ，Krishnan M ，Lightfoot DJ ，Athman A ，Jacobs AK ，Watson-Haigh NS ，Plett D ，Munns R ，Tester M ，Gilliham M ... -  《-》

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

Xu B ，Waters S ，Byrt CS ，Plett D ，Tyerman SD ，Tester M ，Munns R ，Hrmova M ，Gilliham M ... -  《-》

Major genes for Na+ exclusion, Nax1 and Nax2 (wheat HKT1;4 and HKT1;5), decrease Na+ accumulation in bread wheat leaves under saline and waterlogged conditions.

James RA ，Blake C ，Byrt CS ，Munns R ... -  《-》

Wheat grain yield on saline soils is improved by an ancestral Na⁺ transporter gene.

Munns R ，James RA ，Xu B ，Athman A ，Conn SJ ，Jordans C ，Byrt CS ，Hare RA ，Tyerman SD ，Tester M ，Plett D ，Gilliham M ... -  《-》

A conserved primary salt tolerance mechanism mediated by HKT transporters: a mechanism for sodium exclusion and maintenance of high K(+)/Na(+) ratio in leaves during salinity stress.

Hauser F ，Horie T 《-》