盐胁迫下宁夏枸杞根系Na~+、K~+平衡及抑制剂对其影响的研究

以宁夏枸杞为试验材料,利用非损伤微测技术及原子吸收分光光度法,研究NaCl胁迫下枸杞根系中Na~+、K~+吸收转运及质膜Na~+/H~+逆向转运蛋白抑制剂阿米洛利和质膜H~+-ATPase抑制剂矾酸钠对宁夏枸杞根系离子平衡的影响。结果表明:随着NaCl胁迫浓度的增加,枸杞根系中Na~+含量总体升高,与对照差异不显著;K~+含量呈先升后降趋势;Na~+/K~+呈先降后升趋势,且低于对照;Na~+外排先增加后减少,K~+外排降低,且显著高于对照。随着胁迫时间的延长,枸杞根系中Na~+、K~+含量增加,Na~+外排逐渐减慢,K~+外排增加;阿米洛利与矾酸钠均显著降低了盐诱导下的Na~+和H~+内流。NaCl胁迫下宁夏枸杞根系借助于其质膜上的Na~+/H~+逆向运输系统,将胞内过量的Na~+排出胞外,同时抑制K~+外排,保持细胞内较低的Na~+/K~+,维持胞内Na~+、K~+平衡,从而表现出较强的耐盐性。

Effect of salt stress and inhibitor on uptake and transportation of Na+ and K+ in the root of Ningxia Lycium barbarum L.

We detected absorption and transportation of Na⁺, K⁺ in the root of Ningxia Lycium barbarum L. under NaCl stress by using non-invasive micro-test technology and atomic absorption spectrophotometry. The results showed that the root exhibited a higher capacity to induce the Na⁺ efflux compared with that of control. The higher the concentration of NaCl, the more Na⁺ accumulated in the root, but have no significant difference with CK. The K⁺ content increased first and then declined, and the Na⁺/K⁺ ratio showed the opposite trend. The longer duration of NaCl treatment, the more Na⁺ and K⁺ accumulated. At the mean time, the lower Na⁺ efflux and higher K⁺ efflux were also observed in the root compared with that of control. These results suggested that initial salt stress enhanced the salt-elicited Na⁺ efflux but inhibited K⁺ efflux to maintain the lower Na⁺/K⁺ ratio and cellular Na⁺/K⁺ homeostasis. The NaCl-induced Na⁺ efflux and H⁺ influx were inhibited by amiloride (a Na⁺/H⁺ antiporter inhibitor) or sodium orthovanadate (a plasma membrane H⁺-ATPase inhibitor), indicating that Na⁺ extrusion in the root of Ningxia Lycium barbarum L. arises from the active Na⁺/H⁺ antiporter across the plasma membrane.