Multiphasic uptake of potassium by corn roots: no linear component

Area of Science:

• Plant Physiology
• Molecular Transport
• Biophysics

Background:

• Previous studies suggested distinct saturable and linear components for potassium uptake in corn roots.
• These components were interpreted as separate mechanisms governing nutrient transport.
• The established model for potassium uptake concentration dependence was based on these dual components.

Purpose of the Study:

• To re-evaluate the interpretation of potassium uptake concentration-dependence data in corn roots.
• To test the compatibility of existing data with the proposed dual-component model.
• To propose an alternative model for solute uptake mechanisms in plants.

Main Methods:

• Comprehensive analysis of published concentration-dependence data for potassium uptake by corn roots.
• Mathematical modeling to assess the fit of data to different uptake models (dual-component vs. multiphasic isotherms).
• Comparison of model predictions with experimental findings for potassium and other solute uptake.

Main Results:

• The concentration-dependence data for potassium uptake were found to be incompatible with the saturable and linear component model.
• The data were precisely represented by multiphasic isotherms, aligning with findings for other solute uptake.
• This suggests a unified mechanism rather than two distinct ones for potassium uptake.

Conclusions:

• The concept of separate saturable and linear components for potassium uptake in corn roots is not supported by the data.
• Multiphasic isotherms provide a more accurate representation of potassium and other solute uptake kinetics.
• Plant solute uptake is proposed to be mediated by multistate entities exhibiting carrier-like behavior at low concentrations and channel-like behavior at high concentrations.