REGULATION OF THE SUPEROXIDE ANION GENERATION IN TOMATO ROOTS SUSCEPTIBLE AND RESISTANT TO NEMATODES

Abstract

Tomato roots susceptible and resistant to root-knot nematodes were tested far their ability to produce superoxide anions measured as the NADPH-cytochrome c reductase activity that was inhibited by superoxide dismutase (SOD). NADPH oxidase activity of isolated microsomes was completely inhibited by the addition of SOD. Microsomal and cell extract activities, measured with high NADPH concentrations, were higher in resistant than in susceptible roots. Microsomal activity was inhibited by Ca²[sup+] and acetylcholine. The nature of the Ca²[sup+] inhibition and the extent of acetylcholine inhibition were different between the two tomato cvs tested. Nematode attack did not significatively change microsomal activity in both cvs.