Alkali grass resists salt stress through high [K+] and an endodermis barrier to Na+
Alkali grass resists salt stress through high [K+] and an endodermis barrier to Na+
复制标题
DOI：
10.1093/jxb/erh071
复制
发表时间：
2004-04-01
影响因子：
6.9
通讯作者：
Tang, ZC
中科院分区：
文献类型：
--
作者：
Peng, YH;Zhu, YF;Tang, ZC
为了解碱茅(Puccinellia Tenuiflora)与小麦(Triticum aestivum L.)的耐盐机制，采用离子元素分析和X射线微区分析方法，研究了碱茅根部和地上部[K+]、[Na+]对盐胁迫的响应。在溶液培养条件下，研究了不同盐、钾处理条件下植物体内K+、Na+的快速内流，以及植物适应长期胁迫过程中K+、Na+的积累。与小麦相比，碱草在正常和盐分条件下对K+的吸收明显高于小麦，电生理分析表明这种不同的吸收可能是由于质膜对K+/Na+的选择性较高所致。当外源[K+]较高时，外源Cs+对K+的吸收和向地上部的运输均受到抑制，而TEA(四乙基铵)仅抑制K+从根系向地上部的运输。当植物处于K+饥饿状态时，Cs+对K+的吸收没有影响。X射线显微分析表明，碱性草根内胚层细胞中存在高[K+]和低[Na+]，提示这可能是Cs+抑制发生的组织。这些结果表明，钾通道对K+/Na+的选择性和质外体屏障--内皮层的凯氏带的存在，导致了根组织中K+和Na+的横向梯度，不仅导致了根中[K+]的高水平，而且根与地上部之间的[Na+]梯度也很大。
In order to understand the salt-tolerance mechanism of alkali grass (Puccinellia tenuiflora) compared with wheat (Triticum aestivum L.), [K+] and [Na+] in roots and shoots in response to salt treatments were examined with ion element analysis and X-ray microanalysis. Both the rapid K+ and Na+ influx in response to different NaCl and KCl treatments, and the accumulation of K+ and Na+ as the plants acclimated to long-term stress were studied in culture- solution experiments. A higher K+ uptake under normal and saline conditions was evident in alkali grass compared with that in wheat, and electrophysiological analyses indicated that the different uptake probably resulted from the higher K+/Na+ selectivity of the plasma membrane. When external [K+] was high, K+ uptake and transport from roots to shoots were inhibited by exogenous Cs+, while TEA (tetraethylammonium) only inhibited K+ transport from the root to the shoot. K+ uptake was not influenced by Cs+ when plants were K+ starved. It was shown by X-ray microanalysis that high [K+] and low [Na+] existed in the endodermal cells of alkali grass roots, suggesting this to be the tissue where Cs+ inhibition occurs. These results suggest that the K+/Na+ selectivity of potassium channels and the existence of an apoplastic barrier, the Casparian bands of the endodermis, lead to the lateral gradient of K+ and Na+ across root tissue, resulting not only in high levels of [K+] in the shoot but also a large [Na+] gradient between the root and the shoot.