Department of Land, Air and Water Resources, University of California, Davis, California 95616.
Plant Physiol. 1978 Sep;62(3):402-5. doi: 10.1104/pp.62.3.402.
The evidence on how ions accumulated in the root symplasm are released to the xylem vessels is examined. It is suggested that Mitchell's chemiosmotic hypothesis as applied to ion transport might account for the process. A model based on this hypothesis shows the symplasm as an osmotic unit connecting two isolated solutions, but with no significant difference in proton motive force across the unit. If it is assumed that the resistance to transport by plasmalemma uniports and antiports differs in the cortical and stelar ends of the symplasm, the model will provide for an influx of ions to the xylem. The reported properties of isolated steles suggests that the porters (carriers) do have properties in accord with the model.
本文考察了离子在根共质体中积累后如何释放到木质部导管中的证据。有人认为，米切尔的化学渗透假说应用于离子运输，可以解释这一过程。基于该假说的一个模型表明，共质体是一个渗透单位，连接两个隔离的溶液，但质子动力势在单位内没有显著差异。如果假设质膜单向和反向转运体的转运阻力在共质体的皮层和茎端不同，那么该模型将为离子向木质部的内流提供依据。已报道的分离茎段的性质表明，载体（载体）确实具有与模型一致的性质。
