Salicylate‐collapsed membrane potential in pea stem mitochondria

Abstract

Salicylate, acetylsalicylate, benzoate and 3,5‐diiodosalicylate were examined for their effects on pea ( Pisum sativum L. cv. Alaska) stem mitochondria and on a tonoplast‐enriched fraction. Salicylate collapsed the transmembrane electrochemical potential of mitochondria and the ATP‐dependent proton gradient of the tonoplast‐enriched vesicle preparation. Benzoate and acetylsalicylate did not show any effect, while 3,5‐diiodosalicylate inhibited both basal O 2 consumption and ATPase activity of pea mitochondria. Salicylate seems to act as a protonophore. However, its effect is evident only at concentrations higher than those required by classical protonophores and, in addition, can be abolished after removing salicylate from the incubation medium. The activity of salicylate appears linked to the presence of the free phenolic hydroxyl on the benzene ring.