Siddiqi M Y, Glass A D
Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 2B1.
Plant Physiol. 1986 May;81(1):1-7. doi: 10.1104/pp.81.1.1.
By means of a modified Michaelis-Menten equation for K(+) influx, which includes terms for root and external K(+) concentrations (root [K(+)] and K(+), respectively) it is possible to predict the manner in which short-term (perturbation) fluxes of K(+) into roots of barley plants (Hordeum vulgare cv Fergus) vary with root [K(+)] and K(+). Influx values derived from this equation were used to predict changes of root and shoot [K(+)] and K(+) absorption rates (as functions of time and K(+)) from a knowledge of K(+) efflux, relative growth rates of roots and shoots, and the partitioning of absorbed K(+) between these organs. A microcomputer program was employed to model these changes in low-salt plants following transfer to solutions in which K(+) was maintained at values ranging from 5 to 1000 millimoles per cubic meter. The model was operated on the basis of 10 minute absorption periods which provided data for continuous ;updating' of tissue [K(+)]. The simulations were undertaken for periods corresponding to 30 days. During this time the model accurately predicted the manner in which K(+) influx and root and shoot [K(+)] gradually approach values which are essentially independent of K(+). The computer program was also used to predict the outcome of changing various external and internal parameters of the proposed regulatory system. The results of these simulations are discussed in the context of current models for negative feedback control of ion fluxes.
通过一个修正的米氏方程来描述钾离子内流，该方程包含了根部和外部钾离子浓度（分别为根部[K⁺]和[K⁺]₀）的项，从而可以预测钾离子短期（扰动）流入大麦植株（Hordeum vulgare cv Fergus）根部的通量随根部[K⁺]和[K⁺]₀的变化方式。从该方程得出的内流值被用于根据钾离子外流、根和地上部的相对生长速率以及这些器官间吸收钾离子的分配情况，预测根部和地上部[K⁺]的变化以及钾离子吸收速率（作为时间和[K⁺]₀的函数）。使用一个微型计算机程序对低盐植物转移到[K⁺]₀维持在每立方米5至1000毫摩尔范围内的溶液后的这些变化进行建模。该模型基于10分钟的吸收期运行，这为连续“更新”组织[K⁺]提供了数据。模拟进行了相当于30天的时间段。在此期间，该模型准确地预测了钾离子内流以及根部和地上部[K⁺]逐渐接近基本独立于[K⁺]₀的值的方式。该计算机程序还被用于预测改变所提出调节系统的各种外部和内部参数的结果。在当前离子通量负反馈控制模型的背景下讨论了这些模拟结果。
