沙枣幼苗根尖离子流对NaCl胁迫的响应

doi:10.17521/cjpe.2016.0091

摘要/Abstract

摘要：

为了进一步从离子动态运输方面了解沙枣(Elaeagnus angustifolia)耐盐机制和揭示沙枣种源间的K⁺/Na⁺平衡调控差异, 该研究利用非损伤微测技术(non-invasive micro-test technology, NMT)测定银川种源(盐敏感型)和阿拉尔种源(耐盐型)沙枣幼苗根系在3种不同NaCl处理方式下的离子流: 1)在150 mmol·L^-1 NaCl胁迫24 h后的Na⁺和K⁺离子流; 2) NaCl瞬时处理后的K⁺和H⁺的动态离子流; 3)先NaCl胁迫24 h, 再用Na⁺/H⁺逆向转运体抑制剂阿米洛利(Amiloride)和K⁺通道抑制剂氯化四乙胺(TEA)处理后的Na⁺和K⁺离子流。结果表明: NaCl胁迫24 h后, 沙枣根系Na⁺和K⁺外排净流量显著增加, 并且银川种源沙枣幼苗根系Na⁺净流量显著低于阿拉尔种源, 净流量分别为720和912 pmol·cm^-2·s^-1, 而K⁺外流净流量显著高于阿拉尔种源。瞬时NaCl处理后, 沙枣根系K⁺的外流迅速增加, 并且银川种源的K⁺外排净流量始终高于阿拉尔种源, 而H⁺由内流转为外排, 阿拉尔种源的H⁺净外流量大于银川种源。NaCl和NaCl + Amiloride处理下, 阿拉尔种源沙枣幼苗Na⁺外流的净流量均大于银川种源, 但K⁺外流的净流量均小于银川种源, 而在对照和NaCl + TEA处理下, Na⁺和K⁺的净流量在两个种源间无明显差异。研究证明NaCl胁迫造成根系Na⁺积累和K⁺外流, 沙枣幼苗为减少Na⁺积累, 通过根系Na⁺/H⁺逆向转运体将Na⁺从体内排出, 并且耐盐型种源沙枣幼苗根系在NaCl胁迫时能更好地维持体内的K⁺/Na⁺平衡, 其原因主要在于具有较强的Na⁺外排能力和较弱的K⁺流失。该研究可以为进一步发掘优良耐盐沙枣种质资源提供理论参考依据。

关键词: 沙枣, NaCl胁迫, 离子流, 种源, Na⁺/H⁺逆向转运体, K⁺/Na⁺平衡

Abstract:

Aims Elaeagnus angustifolia is one of the most salt-tolerant species. The objective of this study was to understand the mechanisms of ion transporation in E. angustifolia exposed to different salt concentrations through manipulations of K⁺/Na⁺ homeostasis.
Methods Seedlings of two variants of the species, Yinchuan provenance (YC, salt-sensitive type) and the Alaer provenance (ALE, salt-tolerant type), were treated with three different NaCl application modes, and the ion fluxes in the apical regions were measured using non-invasive micro-test technology (NMT). In mode 1, Na⁺ and K⁺ fluxes were measured after 150 mmol·L^-1 NaCl stress lasted for 24 h. In mode 2, K⁺ and H⁺ fluxes were quantified with a transient stimulation of NaCl solution. In mode 3, Amiloride (Na⁺/H⁺ antiporters inhibitor) and tetraethylammonium (TEA, K⁺channel inhibitor) was used to treat apical regions of E. angustifolia seedlings after NaCl stress for 24 h, respectively.
Important findings Under NaCl stress for 24 h, net effluxes of Na⁺ and K⁺ were increased significantly. The net Na⁺effluxes of YC provenance seedlings (720 pmol·cm^-2•s^-1) were lower than that of ALE provenance (912 pmol·cm^-2·s^-1), but the net K⁺ efflux was higher in YC provenance. Under the instantaneous NaCl stimulation, net K⁺ efflux was remarkably increased, with the net K⁺ efflux of YC provenance always higher than that of ALE provenance. Interestingly, H⁺ at the apical regions was found from influx to efflux, with the net H⁺ efflux of ALE provenance greater than that of the YC provenance. Under the NaCl and NaCl + Amiloride treatment, the net Na⁺ efflux of ALE provenance seedlings was higher than that of YC provenance, while the net K⁺ efflux was less in ALE provenance seedlings. On the other hand, the differences in net Na⁺ and K⁺ effluxes were insignificant between the two provenances under the control group and NaCl + TEA treatment. In conclusion, NaCl stress caused Na⁺ accumulation and K⁺ outflows of E. angustifolia seedlings; The E. angustifolia seedlings utilize Na⁺/H⁺ antiporters to reduce Na⁺ accumulation by excretion; and the maintenance of K⁺/Na⁺ homeostasis in salt-tolerant E. angustifolia provenance seedlings roots accounted for a greater Na⁺ extrusion and a lower K⁺ efflux under NaCl stress. Results from this study provide a theoretical basis for further exploring salt-tolerant E. angustifolia germplasm resource.

Key words: Elaeagnus angustifolia, NaCl stress, ion fluxes, provenance, Na^⁺/H⁺ antiporters, K⁺/Na⁺ homeostasis

杨升, 张华新, 陈秋夏, 杨秀艳. 沙枣幼苗根尖离子流对NaCl胁迫的响应. 植物生态学报, 2017, 41(4): 489-496. DOI: 10.17521/cjpe.2016.0091

Sheng YANG, Hua-Xin ZHANG, Qiu-Xia CHEN, Xiu-Yan YANG. Responses of apical ion fluxes to NaCl stress in Elaeagnus angustifolia seedlings. Chinese Journal of Plant Ecology, 2017, 41(4): 489-496. DOI: 10.17521/cjpe.2016.0091

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2016.0091

https://www.plant-ecology.com/CN/Y2017/V41/I4/489

图/表 6

图1 NaCl胁迫对两个种源沙枣幼苗根系稳态Na+流的影响(平均值±标准误差, n = 4)。ALE, 阿拉尔; YC, 银川。不同小写字母表示不同处理和种源间差异显著(p < 0.05)。

Fig. 1 Effects of NaCl stress on steady-state Na+ flux at apical regions of two provenances of Elaeagnus angustifolia (mean ± SE, n = 4). ALE, Alaer; YC, Yinchuan. Different lowercase letters indicate significant differences between different treatments and provenances (p < 0.05).

图2 NaCl胁迫对两个种源沙枣幼苗根系稳态K+流的影响(平均值±标准误差, n = 4)。ALE, 阿拉尔; YC, 银川。不同小写字母表示不同处理和种源间差异显著(p < 0.05)。

Fig. 2 Effects of NaCl stress on steady-state K+ flux at apical regions of two provenances of Elaeagnus angustifolia (mean ± SE, n = 4). ALE, Alaer; YC, Yinchuan. Different lowercase letters indicate significant differences between different treatments and provenances (p < 0.05).

图3 NaCl胁迫诱导两个种源沙枣幼苗根系瞬时K+流的动态差异(平均值±标准误差, n = 4)。不同小写字母表示同一时间点种源间差异显著(p < 0.05)。

Fig. 3 Differences of NaCl stress on transient K+ kinetics at apical regions of two provenances of Elaeagnus angustifolia (mean ± SE, n = 4). Different lowercase letters indicate significant differences between provenances at the same time (p < 0.05).

图4 NaCl胁迫诱导两个种源沙枣幼苗根系瞬时H+流的动态差异(平均值±标准误差, n = 4)。不同小写字母表示同一时间点种源间差异显著(p < 0.05)。

Fig. 4 Differences of NaCl stress on transient H+ kinetics at apical regions of two provenances of Elaeagnus angustifolia (mean ± SE, n = 4). Different lowercase letters indicate significant differences between provenances at the same time (p < 0.05).

图5 两种抑制剂对NaCl胁迫后两个种源沙枣根系Na+流的影响(平均值±标准误差, n = 4)。ALE, 阿拉尔; YC, 银川。不同小写字母表示同一种源不同处理间差异显著(p < 0.05); 不同大写字母表示相同处理不同种源间差异显著(p < 0.05)。

Fig. 5 Effects of two kinds of inhibitors on net Na+ flux at apical regions of two provenances of Elaeagnus angustifolia treated by NaCl stress (mean ± SE, n = 4). ALE, Alaer; YC, Yinchuan. Different lowercase letters indicate significant differences among different treatments in the same provenance (p < 0.05), While different capital letters indicate significant difference between provenances at the same treatment (p < 0.05).

图6 两种抑制剂对NaCl胁迫后两个种源沙枣根系K+流的影响(平均值±标准误差, n = 4)。ALE, 阿拉尔; YC, 银川。不同小写字母表示同一种源不同处理间差异显著(p < 0.05); 不同大写字母表示相同处理不同种源间差异显著(p < 0.05)。

Fig. 6 Effects of two kinds of inhibitors on net K+ flux at apical regions of two provenances of Elaeagnus angustifolia treated by NaCl stress (mean ± SE, n = 4). ALE, Alaer; YC, Yinchuan. Different lowercase letters indicate significant differences among different treatments in the same provenance (p < 0.05), While different capital letters indicate significant difference between provenances at the same treatment (p < 0.05).

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