盐胁迫下宁夏枸杞Na^+吸收及Na^+/H^+转运蛋白与H^+-ATPase基因表达的研究

Effects of Salt Stress on Na^+Uptake and Expression of Na^+/H^+Transporter and H^+-ATPase Genes in Lycium barbarum L.

为从分子水平揭示宁夏枸杞钠的吸收积累机理,本试验采用原子吸收分光光度法和实时荧光定量PCR(RT-qPCR)方法,对盐胁迫下宁夏枸杞根中Na^+、K^+含量以及质膜和液泡膜Na^+/H^+转运蛋白与H^+-ATPase基因表达水平进行测定分析。结果表明,相同胁迫时间下,随着NaCl处理浓度的增加,枸杞根系中Na^+浓度总体呈缓慢增加趋势,K^+含量呈先增加后减少趋势,Na^+/K^+比值呈先减少后增加趋势;编码质膜和液泡膜的Na^+/H^+转运蛋白基因LbSOS1、LbNHX1以及液泡膜H^+-ATPase基因LbVHA-C1表达量均呈升高趋势,质膜H^+-ATPase基因LbHA1表达量呈先升高后降低趋势。相同NaCl处理浓度下,随着胁迫时间的延长,Na^+含量总体呈增加趋势,K^+含量呈先增加后减少趋势,Na^+/K^+比值呈增加趋势。LbSOS1、LbNHX1表达量总体呈先升高后降低趋势,LbVHA-C1、LbHA1表达量总体呈降低的趋势。相关性分析显示,不同胁迫时间下,枸杞根中LbSOS1、LbNHX1、LbVHA-C1和LbHA1表达量与Na^+含量存在一定的正相关或负相关。上述结果表明,在低浓度NaCl胁迫时,维持枸杞体内较高的K^+/Na^+比值是宁夏枸杞耐盐的主要方式之一,同时也说明在胁迫初期,质膜和液泡膜的Na^+/H^+转运蛋白与H^+-ATPase参与了枸杞细胞中Na^+及时排出胞外和区隔于液泡,从而保持了根细胞内Na^+的稳定性。此外,随着胁迫时间的延长和NaCl处理浓度的增加,LbSOS1、LbNHX1、LbVHA-C1和LbHA1的表达水平均降低,而Na^+积累量大幅增加,致使枸杞抗盐性降低。本研究揭示了宁夏枸杞的耐盐机理,为利用宁夏枸杞改良宁夏大面积盐碱地提供了理论依据。

To investigate the mechanism of Na^+uptake and accumulation Lycium barbarum L.The contents of Na^+and K^+in the roots of Lycium barbarum L.was determined using atomic absorption spectrophotometry under different salt treatments.Meanwhile,the expression levels of Na^+/H^+transporter and H^+-ATP enzyme involved in ion transport in plasm member and tonoplast were determined by quantitative real time PCR.The results showed that the plant exhibited slow increasing in Na^+content in response to salt stress.However,the K^+content increased and then decreased,the ratio of Na^+/K^+decreased and then increased.The expression abundance of LbSOS1、LbNHX1and LbVHA-C1 in plasm membrane and tonoplast remained relatively higher but LbHA1 increased and then decreased.Long-term stress of NaCl induced the accumulation of Na^+but decreased K^+content,and the ratio of Na^+/K^+increased.Meanwhile,The expression abundance of LbSOS1、LbNHX1 increased and then decreased but LbVHA-C1 and LbHA1 decreased.Significantly positive or negative correlations was found between the expression level of LbSOS1,LbNHX1,LbVHA-C1 and LbHA1 and the content of Na^+.That indicated retaining higher ratio of K^+/Na^+was one of the main ways of salt tolerance in Lycium barbarum L.under low NaCl concentration.The high express level of Na^+/H^+transporter and H^+-ATP enzyme in plasma membrane and vacuolar membrane could excrete Na^+from the cytoplasm into vacuolar cells at the early stage of stress,but long-term time stress induced the lower expression of LbSOS1,LbNHX1,LbVHA-C1 and LbHA1 and the accumulation of Na^+,which contributed to the reduction of salt tolerance of Lycium barbarum L.The results of this study laid a theoretical foundation for salt-tolerance of Lycium barbarum L.and improvement of saline-alkali soil in large area.