Wherrett Tim, Ryan Peter R, Delhaize Emmanuel, Shabala Sergey
School of Agricultural Science, University of Tasmania, Private Bag 54, Hobart, Tas. 7001, Australia.
CSIRO Plant Industry, PO Box 1600, Canberra, ACT 2601, Australia.
Funct Plant Biol. 2005 May;32(3):199-208. doi: 10.1071/FP04210.
Aluminium (Al) tolerance in wheat (Triticum aestivum L.) is associated with the Al-activated efflux of malate and K from the root apices. We tested the hypothesis that these Al-activated ion fluxes would induce changes in the membrane potential (V) and that these responses would differ between wheat genotypes that differ in Al tolerance. Within minutes of exposing wheat roots to 50 μm AlCl, a significant depolarisation was measured in the Al-tolerant ET8 genotype but not in a near-isogenic, Al-sensitive genotype, ES8. We investigated the ion movements that may be responsible for these changes in V by measuring real-time fluxes of Cl, H and K at the root apices of wheat seedlings using the non-invasive microelectrode ion flux estimation (MIFE) technique. Addition of 50 μm AlCl to the bathing solution stimulated an increase in K efflux and H influx in ET8 but not in ES8. The differences between the genotypes were sustained for 24 h and were observed only at the elongating zone and not the meristematic zone. After 24 h Al increased Cl influx in ET8 but inhibited ES8 influx in a dose-dependent manner. These results provide new temporal and spatial information on the Al-activated ion fluxes from intact wheat plants.
小麦（Triticum aestivum L.）对铝（Al）的耐受性与苹果酸和钾从根尖的铝激活外流有关。我们检验了这样一个假设，即这些铝激活的离子流会引起膜电位（V）的变化，并且这些反应在铝耐受性不同的小麦基因型之间会有所不同。在将小麦根暴露于50μm AlCl₃后的几分钟内，在耐铝基因型ET8中检测到显著的去极化，但在近等基因的铝敏感基因型ES8中未检测到。我们使用非侵入性微电极离子通量估算（MIFE）技术，通过测量小麦幼苗根尖处Cl⁻、H⁺和K⁺的实时通量，研究了可能导致这些V变化的离子运动。向浴液中添加50μm AlCl₃会刺激ET8中K⁺外流和H⁺内流增加，但在ES8中不会。基因型之间的差异持续了24小时，并且仅在伸长区观察到，而在分生区未观察到。24小时后，铝增加了ET8中Cl⁻的内流，但以剂量依赖的方式抑制了ES8中的Cl⁻内流。这些结果提供了关于完整小麦植株中铝激活离子流的新的时间和空间信息。
