Measurement of 33P-PO4 Absorption Kinetic Constants in Arabidopsis

Abstract

Based on the Michaelis-Menten kinetics model (Hofstee, 1952), this method allows calculation of the kinetic parameters (Vmax, Km) of phosphate uptake by Arabidopsis roots. This method is based on the quantification of phosphate uptake by Arabidopsis roots as described in Thibaud and Marin (2016), except that a range of phosphate concentration is applied in the incubation medium. Plants are grown in high or low Pi giving access to kinetic parameters corresponding to low and high affinity respectively. In high Pi, the high-affinity transporters are not induced giving access to the low-affinity transport only. When plants are grown in low Pi, high affinity transporters are active, and the corresponding kinetic parameters can be measured. The calculation of Km and Vmax values is based on the Michaelis-Menten kinetics model.