打顶对烤烟植株钾素代谢和钾离子通道基因表达的影响

Effects of Topping on Potassium Metabolism and Expression of Potassium Channels in Tobacco Plants

【目的】定量检测打顶对烟株钾离子通道基因表达的影响,为从分子水平上研究打顶对烟草钾素营养调控机理提供理论依据。【方法】在盆栽基质培养条件下,利用实时荧光定量PCR技术检测了打顶后(1h、5h、24h和14d)烟株钾离子通道基因表达的变化,并通过酶联免疫法分析烟株内源激素的含量。【结果】与不打顶处理比较,打顶能够降低整株钾累积量,有利于钾素向叶和根中分配;能够抑制NKT1和NTORK1基因在叶中表达,诱导其在根中表达。NKT1叶中表达量高于根,NTORK1在打顶后24h内叶中表达量高于根,打顶后14d根中表达量高于叶。根中钾离子通道基因表达是调控根系钾素累积和决定地上部K+浓度的关键。打顶有利于K+从根系细胞质膜中流出,导致由根系向地上部运输的K+减少,从而使烟叶中钾累积量降低。打顶对钾离子通道基因表达的调控作用与烟株内源激素水平变化有关,打顶后叶中IAA含量降低,根中IAA含量增加,其中14d时根中IAA比不打顶处理增加了140.7%。【结论】打顶后烟株内源激素水平变化可能是调控钾离子通道基因表达的主要原因,而钾离子通道基因表达的变化直接影响着烟株体内钾素累积和分配。

[Objective] In order to provide a theoretical basis for the potassium regulation metabolism, this paper analyzed the effects of topping on the expression of potassium channel genes in flue-cured tobacco. [Method] Real-time fluorescence quantitative PCR was used to detect the relative expression change of potassium channel genes, and endogenesis auxin （IAA） was detected by ELISA in tobacco through pot experiments. [Result] As compared with the control, the potassium accumulation in whole plant of decapitated tobacco decreased and there was more potassium distribution in leaves and roots. The expressions of NKT1 and NTORK1 genes in leaves were inhibited by topping, but not in roots. The expression of both NKT1 and NTORK1 in leaves was higher than that in roots within 24 h, except 14 d while it was reversed in the two tissues. The variations of expression of potassium channel genes in roots could control potassium accumulation and regulate K＋ concentration in aerial parts. Further results showed that the level of endogenesis IAA, which declined in leaves and increased in roots by 140.7% at 14 d compared to the control plant, was attributed to the expression change of potassium channels. [Conclusion] The variations of expression of potassium channel genes are likely to be caused by the endogenesis hormone in tobacco after topping, and it has a direct impact on the potassium accumulation and distribution simultaneously.