Cellular mechanisms of potassium transport in plants

Abstract

Potassium (K(+)) is the most abundant ion in the plant cell and is required for a wide array of functions, ranging from the maintenance of electrical potential gradients across cell membranes, to the generation of turgor, to the activation of numerous enzymes. The majority of these functions depend more or less directly upon the activities and regulation of membrane-bound K(+) transport proteins, operating over a wide range of K(+) concentrations. Here, we review the physiological aspects of potassium transport systems in the plasma membrane, re-examining fundamental problems in the field such as the distinctions between high- and low-affinity transport systems, the interactions between K(+) and other ions such as NH(4)(+) and Na(+), the regulation of cellular K(+) pools, the generation of electrical potentials and the problems involved in measurement of unidirectional K(+) fluxes. We place these discussions in the context of recent discoveries in the molecular biology of K(+) acquisition and produce an overview of gene families encoding K(+) transporters.

Sodium as nutrient and toxicant

“…While the maintenance of a high K + /Na + activity ratio in the cytosol of plant root cells is frequently described in the literature as being a critical determinant of plant performance under salinity stress, direct evidence supporting this contention is, by comparison, extremely rare. While there is a strong consensus from independent lines of evidence that the cytosolic levels of K + in plant cells are typically around 100 mM Britto and Kronzucker 2008), measurements of cytosolic Na + differ dramatically from one another, depending on the methods used . This can be illustrated by comparing two studies examining the same pair of barley cultivars, one using X-ray microanalysis , the other using intracellular Na + -specific electrodes (Carden et al 2003); estimates from the two studies disagree from 4-to 90-fold (although it should be noted that different exposure times to elevated NaCl were used).…”

mRNA-Seq Reveals a Comprehensive Transcriptome Profile of Rice under Phosphate Stress

“…Genetic modification of Pi transport proteins are maybe the key in developing tolerance to both -P and ++P stress. Britto and Kronzucker (2008) reported that the high-affinity transport system is strongly downregulated under K + -replete conditions and is conversely strongly upregulated under K + -starvation conditions and that the LATS (low-affinity transport system)-range K + influx may be increased generally by increased K + (Britto and Kronzucker. 2008).…”

Elymus dahuricus H+-PPase EdVP1 enhances potassium uptake and utilization of wheat through the development of root system

“…The organic acid contents in root exudates were determined by HPLC Agilent 1100 and DAD detector with wavelength of 210 nm. Root excretion H + was determined using the method as described by Britto and Kronzucker (2008):…”