Relative fluxes of phosphates (Pi) and sugars (C) across the fungal plasma membrane. Without additional Pi-source in the apoplast (value 0 at the x-axis, black dots) there is a constant flux of phosphate via the proton-coupled phosphate (H/P) transporter from the fungus to the apoplast and a constant flux of sugar from the apoplast to the fungus. For better comparison these fluxes were normalized to 1 and -1, respectively, and all other fluxes were calculated relative to these control values. With increasing ATP-release and Pi-production the Pi-efflux gets smaller and is zero at a relative Pi-production rate of 1 (grey triangles). At higher ATP-release and Pi-production rates the fungus imports Pi, i.e. the transport direction of phosphate has been inverted in comparison to the control condition (white square). The C-flux via the proton-coupled sugar (H/C) transporter is not affected by the additional Pi-source (horizontal grey line). 