Trans-Root Electrical Potential in Roots ofPlantago mediaL. as Affected by Hydrostatic Pressure: The Induction of an O2Deficient Root Core

摘要

Excised roots ofPlantago mediaL. were subjected to small hydrostatic pressure gradients. Pressure applied with a displacement pump easily extracted gas present in cortical lacunae consequent on the gas saturation deficit of the bathing solution. The temporary pressure treatment resulted in an irreversible decrease in the O2diffusion rate through the root tissue and consequently in O2deficient root cores.Therefore electrogenic pumps located at the symplast/xylem interface, i.e. in the centre of the root, were inhibited by pressure.The longitudinal distribution of the xylem pumps could be computed: inPlantago mediathey are located in the basal parts of the root. The effect of pressure on the electrogenic xylem pumps demonstrated here should be taken into account when the process of ion transport from the root to the shoot is studied while the root is pressurized.