The Na+ transporter, TaHKT1;5-D, limits shoot Na+ accumulation in bread wheat
The Na+ transporter, TaHKT1;5-D, limits shoot Na+ accumulation in bread wheat
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DOI：
10.1111/tpj.12651
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发表时间：
2014-11-01
期刊：
影响因子：
7.2
通讯作者：
Gilliham, Matthew
中科院分区：
文献类型：
--
作者：
Byrt, Caitlin Siobhan;Xu, Bo;Gilliham, Matthew
面包小麦（Triticum aestivum L.）具有一个主要的耐盐基因座，Kna1，负责维持盐胁迫植物叶片中高的胞质K +/Na+比。Kna1基因座包含一个大的DNA片段，位于染色体4DL的远端14%。在该位点观察到有限的重组，使得难以进行遗传作图和鉴定致病基因。在这里，我们破译TaHKT1的功能; 5-D，潜在的Kna1位点的候选基因。利用异源表达系统酿酒酵母和非洲爪蟾卵母细胞的转运研究表明，TaHKT1; 5-D是一种Na+选择性转运蛋白。在拟南芥叶肉原生质体中的瞬时表达和原位聚合酶链反应表明TaHKT1; 5-D定位于小麦根中柱的质膜上。RNA干扰诱导的沉默降低了转基因小麦中TaHKT1; 5-D的表达，导致叶片中Na+浓度的增加。这表明TaHKT1; 5-D从根的木质部导管中回收Na+，并在限制Na+从根向叶的运输中起重要作用。因此，TaHKT1; 5-D赋予面包小麦与Kna1位点通过芽Na+排斥相关的基本耐盐机制，并且在保持叶片中高K +/Na+比方面至关重要。这些结果表明，有可能通过操纵HKT1; 5基因来提高面包小麦的耐盐性。
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.