Differentiation of low-affinity Na+ uptake pathways and kinetics of the effects of K+ on Na+ uptake in the halophyte Suaeda maritima
Differentiation of low-affinity Na+ uptake pathways and kinetics of the effects of K+ on Na+ uptake in the halophyte Suaeda maritima
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DOI：
10.1007/s11104-012-1552-5
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发表时间：
2013-07
期刊：
影响因子：
4.9
通讯作者：
Jinlin Zhang;T. Flowers;Suo-min Wang
中科院分区：
文献类型：
--
作者：
Jinlin Zhang;T. Flowers;Suo-min Wang
背景和目的盐度是全球农业生产日益严重的问题。了解Na+如何进入植物是重要的，如果要实现减少Na+内流，Na+的积累在植物中的调节和提高作物植物的耐盐性的关键组成部分，。我们以前的工作表明，两个不同的低亲和力Na+吸收途径存在于盐生植物碱蓬。在这里，我们报告的外部NaCl浓度的吸收开关从途径1到途径2和外部K+浓度和Na+吸收和积累之间的相互作用的动力学S。方法采用Na+内流、Na+和K+积累的方法，研究了Na+转运蛋白和K+通道在低亲和力Na+吸收中的作用。暴露于各种浓度的NaCl（0 - 200 mM）的maritima进行了分析，在存在和不存在的抑制剂TEA和Ba+（5 mM TEA或3 mM Ba 2+）或KCl（0，10或50 mM）。maritima：途径1在低盐条件下可能由HKT型转运体介导，途径2在高盐条件下可能由AKT1型通道或KUP/HAK/KT型转运体介导。两个不同的低亲和力Na+摄取从途径1切换到途径2的外部NaCl浓度，即"转折点"，在90和95 mM之间。在短时间（12 h）的Na+和K+处理中，低浓度K+（10 mM）促进了S. maritima在高盐度（100 - 200 mM NaCl），无论植物是否已受到较长（3 d）的K+饥饿期。动力学表明，在高盐（100-200 mM NaCl）条件下，低浓度K+（10 mM）可能激活AKT1型通道或KUP/HAK/KT型转运蛋白。低浓度K+（10 mM）可激活AKT1或KUP/HAK/KT，并促进高盐度（100 - 200 mM NaCl）下Na+的吸收。K+对Na+吸收和积累的动力学S maritima也是一致的，有两个低亲和力的Na+吸收途径。
Background and aimsSalinity is an increasing problem for agricultural production worldwide. Understanding how Na+ enters plants is important if reducing Na+ influx, a key component of the regulation of Na+ accumulation in plants and improving salt tolerance of crop plants, is to be achieved. Our previous work indicated that two distinct low-affinity Na+ uptake pathways exist in the halophyte Suaeda maritima. Here, we report the external NaCl concentration at which uptake switches from pathway 1 to pathway 2 and the kinetics of the interaction between external K+ concentration and Na+ uptake and accumulation in S. maritima in order to determine the roles of K+ transporters or channels in low-affinity Na+ uptake.MethodsNa+ influx, Na+ and K+ accumulations in S. maritima exposed to various concentrations of NaCl (0–200 mM) were analyzed in the absence and presence of the inhibitors TEA and Ba+ (5 mM TEA or 3 mM Ba2+) or KCl (0, 10 or 50 mM).ResultsOur earlier proposal was confirmed and extended that there are two distinct low-affinity Na+ uptake pathways in S. maritima: pathway 1 might be mediated by a HKT-type transporter under low salinity conditions and pathway 2 by an AKT1-type channel or a KUP/HAK/KT type transporter under high salinity conditions. The external NaCl concentration at which two distinct low-affinity Na+ uptake switches from pathway 1 to pathway 2, the ‘turning point’, is between 90 and 95 mM. Over a short period (12 h) of Na+ and K+ treatments, a low concentration of K+ (10 mM) facilitated Na+ uptake by S. maritima under high salinity (100–200 mM NaCl), whether or not the plants had been subjected to a longer (3 d) period of K+ starvation. The kinetics suggests that low concentration of K+ (10 mM) might activate AKT1-type channels or KUP/HAK/KT-type transporters under high salinity (100–200 mM NaCl).ConclusionsThe turning-point of external NaCl concentrations for the two low-affinity Na+ uptake pathways in Suaeda maritima is between 90 and 95 mM. A low concentration of K+ (10 mM) might activate AKT1 or KUP/HAK/KT and facilitate Na+ uptake under high salinity (100–200 mM NaCl). The kinetics of K+ on Na+ uptake and accumulation in S maritima are also consistent with there being two low-affinity Na+ uptake pathways.