Potassium Transport in Corn Roots

Abstract
The relative transport capabilities of the cells of the root periphery and cortex were investigated using a variety of experimental techniques. Brief (30 seconds to 1 minute) exposures with the penetrating sulfhydryl reagent, N-ethyl maleimide (NEM), and the impermeant reagent, p-chloromercuribenzene sulfonic acid (PCMBS), dramatically reduced 86Rb+ (0.2 millimolar RbCl) uptake into 2 centimeter corn (Zea mays [A632 × (C3640 × Oh43)]) root segments. Autoradiographic localization studies with [3H]NEM and [203Hg]PCMBS demonstrated that, during short term exposures with either reagent, sulfhydryl binding occurred almost exclusively in the cells of the root periphery.