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作 者 ：封克;孙小茗;汪晓丽;盛海君

期 刊 ：植物营养与肥料学报 2007年 13卷 5期 页码：877-881

关键词：K+-高亲和转运系统；K+吸收动力学；NH4+抑制；

Keywords:K+-HATS, kineticsofpotassiumuptake, ammoniuminhibition,

摘 要 ：为探讨植物苗期根系高亲和转运系统的K⁺吸收动力学特征及其是否受吸NH₄⁺的影响,采用溶液培养和添加K⁺通道抑制剂的方法,对低K+浓度下5种植物在有铵和无铵时的K⁺吸收动力学特征进行了研究。结果表明,植物根细胞K⁺高亲和系统的吸钾特征曲线符合Michaelich-Menten方程。不同植物K⁺高亲和系统的K^m值之间差异较小,均在50%以内,说明不同植物的载体与K+间的亲和性差异较小;不同植物K⁺高亲和系统的V_max值间差异很大,说明不同植物根细胞膜上的K₄⁺载体数量间差异很大,这是导致不同植物在低钾条件下吸钾能力差异较大的主要原因。铵的存在可以明显降低供试植物在低钾条件下对K⁺的吸收速率。与无NH₄⁺情况比较,NH₄⁺的存在可使大豆K⁺吸收的Vmax减少80%;但NH₄⁺对不同载体与K⁺之间亲和性(K_m的影响较小,由NH4+所导致的Km的降低率均在10%以内。可见,对高亲和系统而言,NH4+对K+吸收的影响主要是由于铵竞争细胞膜上的钾载体所造成的。

Abstract:This paper studied the dynamic characteristics of K⁺ uptake by 5 plants and the effects of NH₄⁺ on K⁺ uptake.The experiment was carried out by hydroponics and with application of ion channel inhibitor TEA at low K⁺ concentration. Under with or without NH₄⁺ the dynamic parameters of ⁺uptake were assessed.The results indicated that the K+ uptake curve by high affinity transport system for K⁺ (K⁺-HATS) in root cells could be described by the Michaelich-Menten equation.There was relatively little difference(below 50%) in Km among different plants,showing a small diversity in affinity of K⁺ -HATS to K⁺.For different plants there was significant difference in Vmax of K⁺-HATS,e.g.the Vmax of wheat was 11 times more than that of soybean,which indicated a great discrepancy in K⁺-carrier number,and this discrepancy resulted in a great diversity in K⁺ uptake of plants under lower K⁺ concentration.Ammonium could greatly decrease the rate of K⁺ uptake by plants.Compared with lack of NH₄⁺the Vmax of soybean was only 20% of that under with NH₄⁺ application.The affinity of K⁺-HATS of plants to K⁺,however,was less affected by NH₄⁺,and reduction of Km for all plants used in this experiment was less than 10%.The results above showed that for the K⁺-HATS of plants the effects of NH₄⁺on the K⁺ uptake were mainly due to competition of NH₄⁺ for the K⁺-carrier at the cell membrane.

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