The Effect of Extracellular Components from Colletotrichum lindemuthianum on Membrane Transport in Vesicles Isolated from Bean Hypocotyl

Abstract

Extracellular components released from mycelia of the α and β races of the bean pathogen, Colletotrichum lindemuthianum, inhibited proton uptake in sealed vesicles prepared from bean hypocotyls. Differential sensitivity of ATP-driven proton transport to nitrate, vanadate, N,N′-dicyclohexylcarbodiimide, diethylstilbestrol, and oligomycin suggested the vesicles were enriched for tonoplast. Anion stimulation of proton transport, by enhancement of ATPase activity and dissipation of the membrane potential, was consistent with this conclusion. Although fungal components inhibited the formation of a pH gradient, the membrane potential was unaffected and the ATPase activity slightly stimulated. These data suggest that the fungal components produce an electroneutral proton exchange. Proton transport in Dark Red Kidney bean tonoplast vesicles was inhibited by mycelial preparations from the incompatible α race and compatible β race. Elicitor activity, however, was greater in the α race fractions. Elicitor purified from α race culture filtrate did not inhibit proton transport in vesicles isolated from Dark Red Kidney bean. Consequently, elicitor activity need not be associated with an ability to impair tonoplast function.