Inhibition of fusicoccin-induced electrogenic proton extrusion in susceptible maize by Helminthosporium maydis race T toxin

Helminthosporium maydis race T toxin (HMT) severely inhibits basal and, to an even larger extent, fusicoccin (FC) induced proton extrusion in susceptible maize root and coleoptile segments. This effect of the toxin also induced a rapid depolarisation of the basal transmembrane electric potential and a severe decrease of FC-induced hyperpolarisation. These data are interpreted as consistent with the hypothesis that HMT and FC antagonistically influence at the plasmalemma a H+-extruding ATPase.