Dual pattern of potassium transport in plant cells: a physical artifact of a single uptake mechanism

• Published in: Journal of experimental botany 1984-12, Vol.35 (161), p.1723-1732
• Main Author: Dalton, F.N
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Cations; Cell membranes; Cell walls; cells; Diffusion coefficient; Economic plant physiology; Fundamental and applied biological sciences. Psychology; Ion concentration; Ions; mathematical models; Plant cells; Plant physiology and development; Plant roots; plants; Potassium; Potassium transport; Rate-enhancing region; Rate-limiting region; roots; transport; uptake; Uptake mechanisms; Water and solutes. Absorption, translocation and permeability; Water relations, transpiration, stomata
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/35.12.1723

Analysis of potassium transport in plant root cells shows two rate-influencing regions: an unstirred boundary layer adjacent to the cell wall acts as a rate-limiting region and the negatively charged cell wall acts as a rate-enhancing region. The rate-enhancing region gives rise to a pseudo ‘dual mechanism’. These two regions act in concert to influence significantly the characteristics of the concentration-dependent potassium uptake process. The anomalous ion uptake behaviour found in the literature is explained on the basis of a single active uptake mechanism operating under the influence of these two regions. The most critical property in support of the concept of a ‘dual mechanism’ for cation uptake in plant roots is explained on this basis. It is unnecessary to invoke separate groups of enzymes, each one of which is active over different concentration ranges. One mechanism operating over the entire concentration range is sufficient.