Scanning ion-selective electrode technique and X-ray microanalysis provide direct evidence of contrasting Na+ transport ability from root to shoot in salt-sensitive cucumber and salt-tolerant pumpkin under NaCl stress
Scanning ion-selective electrode technique and X-ray microanalysis provide direct evidence of contrasting Na+ transport ability from root to shoot in salt-sensitive cucumber and salt-tolerant pumpkin under NaCl stress
复制标题
扫描离子选择电极技术和 X 射线微量分析提供了盐敏感黄瓜和耐盐南瓜在 NaCl 胁迫下从根到地上部 Na 转运能力对比的直接证据
DOI：
10.1111/ppl.12223
复制
发表时间：
2014-12-01
影响因子：
6.4
通讯作者：
Bie, Zhilong
中科院分区：
文献类型：
--
作者：
Lei, Bo;Huang, Yuan;Bie, Zhilong
嫁接耐盐南瓜砧木可提高黄瓜的耐盐性。以前的研究表明，这可以归因于南瓜根具有更高的能力，以限制运输Na+的地上部比黄瓜根。然而，其机制仍不清楚。研究了耐盐南瓜和盐敏感黄瓜在高盐（200 mM）和中等盐（90 mM）胁迫下Na+的运输。离子选择性电极扫描技术表明，在200和90 mMNaCl胁迫下，南瓜根系表现出较高的Na+排出能力，H+内流也相应增加。200 mMNaCl诱导的根内Na+/H+交换可被Na+/H+逆向转运蛋白抑制剂阿米洛利或质膜H+-ATP酶抑制剂钒酸盐抑制，表明盐胁迫下南瓜和黄瓜根的Na+排斥是质膜上活跃的Na+/H+逆向转运蛋白的结果，盐胁迫下南瓜根的Na+/H+逆向转运蛋白系统足以排斥Na+。X射线微区分析表明，在90 mMNaCl胁迫下，南瓜根皮层Na+含量高于黄瓜根，而中柱Na+含量低于黄瓜根，说明南瓜根皮层细胞高度空泡化，能吸收更多的Na+，限制Na+向中柱的径向运输，从而限制Na+向地上部的运输。这些结果提供了直接证据，南瓜根具有更高的能力，以限制运输Na+的地上部比黄瓜根。
Grafting onto salt-tolerant pumpkin rootstock can increase cucumber salt tolerance. Previous studies have suggested that this can be attributed to pumpkin roots with higher capacity to limit the transport of Na+ to the shoot than cucumber roots. However, the mechanism remains unclear. This study investigated the transport of Na+ in salt-tolerant pumpkin and salt-sensitive cucumber plants under high (200mM) or moderate (90mM) NaCl stress. Scanning ion-selective electrode technique showed that pumpkin roots exhibited a higher capacity to extrude Na+, and a correspondingly increased H+ influx under 200 or 90mMNaCl stress. The 200mMNaCl induced Na+/H+ exchange in the root was inhibited by amiloride (a Na+/H+ antiporter inhibitor) or vanadate [a plasma membrane (PM) H+-ATPase inhibitor], indicating that Na+ exclusion in salt stressed pumpkin and cucumber roots was the result of an active Na+/H+ antiporter across the PM, and the Na+/H+ antiporter system in salt stressed pumpkin roots was sufficient to exclude Na+. X-ray microanalysis showed higher Na+ in the cortex, but lower Na+ in the stele of pumpkin roots than that in cucumber roots under 90mMNaCl stress, suggesting that the highly vacuolated root cortical cells of pumpkin roots could sequester more Na+, limit the radial transport of Na+ to the stele and thus restrict the transport of Na+ to the shoot. These results provide direct evidence for pumpkin roots with higher capacity to limit the transport of Na+ to the shoot than cucumber roots.