Over-expression of an Na+- and K+-permeable HKT transporter in barley improves salt tolerance
Over-expression of an Na+- and K+-permeable HKT transporter in barley improves salt tolerance
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DOI：
10.1111/j.1365-313x.2011.04701.x
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发表时间：
2011-11-01
期刊：
影响因子：
7.2
通讯作者：
Very, Anne-Alienor
中科院分区：
文献类型：
--
作者：
Mian, Afaq;Oomen, Ronald J. F. J.;Very, Anne-Alienor
土壤盐碱化是影响地球仪农业的一个日益严重的威胁。植物对高盐浓度的适应涉及到Na+吸收、转运和区室化等多方面的综合调控功能。HKT家族的Na+转运蛋白参与了拟南芥、小麦和水稻等植物对轻度盐胁迫的耐受性，其作用是将Na+从气生组织中排出。在这里，我们分析了HKT转运蛋白HKT 2的作用;1，这是渗透到K+和Na+，在大麦，一个相对耐盐的作物，显示盐，包括行为。在非洲爪蟾卵母细胞中，HvHKT 2;1共转运Na+和K+在一个大的浓度范围内，表现出低亲和力的Na+，可变亲和力的K+依赖于外部Na+浓度，和抑制K+（Ki约5 mM）。HvHKT 2;1主要在根皮层中表达。转录水平上调根和芽低K+生长条件，并在芽高Na+生长条件。HvHKT 2的过表达; 1导致增强Na+的吸收，更高的Na+浓度在木质部汁液，和增强的Na+转运到叶片时，植物生长在50或100 mM NaCl的存在下。有趣的是，这些反应与大麦耐盐性增加相关。这表明，限制大麦耐盐性的因素之一是转移Na+到地上部的能力，而不是这种阳离子在叶组织中的积累或区室化。因此，HvHKT 2;1的过表达通过增强大麦的含盐行为而导致耐盐性增加。
Soil salinity is an increasing menace that affects agriculture across the globe. Plant adaptation to high salt concentrations involves integrated functions, including control of Na+ uptake, translocation and compartmentalization. Na+ transporters belonging to the HKT family have been shown to be involved in tolerance to mild salt stress in glycophytes such as Arabidopsis, wheat and rice by contributing to Na+ exclusion from aerial tissues. Here, we have analysed the role of the HKT transporter HKT2;1, which is permeable to K+ and Na+, in barley, a relatively salt-tolerant crop that displays a salt-including behaviour. In Xenopus oocytes, HvHKT2;1 co-transports Na+ and K+ over a large range of concentrations, displaying low affinity for Na+, variable affinity for K+ depending on external Na+ concentration, and inhibition by K+ (K-i approximately 5 mM). HvHKT2;1 is predominantly expressed in the root cortex. Transcript levels are up-regulated in both roots and shoots by low K+ growth conditions, and in shoots by high Na+ growth conditions. Over-expression of HvHKT2;1 led to enhanced Na+ uptake, higher Na+ concentrations in the xylem sap, and enhanced translocation of Na+ to leaves when plants were grown in the presence of 50 or 100 mM NaCl. Interestingly, these responses were correlated with increased barley salt tolerance. This suggests that one of the factors that limits barley salt tolerance is the capacity to translocate Na+ to the shoot rather than accumulation or compartmentalization of this cation in leaf tissues. Thus, over-expression of HvHKT2;1 leads to increased salt tolerance by reinforcing the salt- including behaviour of barley.