DIFFERENCE IN ISOPEROXIDASE ACTIVITIES OF TOMATO ROOTS SUSCEPTIBLE AND RESISTANT TO ROOT-KNOT NEMATODES

Abstract

Peroxidase from tomato roots susceptible and resistant to root-knot nematodes was purified and its molecular weight calculated by analytical gel-filtration HPLC. Anionic and cationic peroxidases were separated and their kinetic properties measured with guaiacol, syringaldazine and p-phenylendiamine/pyrocathecol as substrates. A marked difference was found between affinities for syringaldazine of cationic peroxidases from susceptible and resistant roots. Isoperoxidases were solubilized from cellular particulate fractions of both root samples, and their activity characterized with the above-mentioned substrates. Reaction rates of mitochondrial guaiacol peroxidase from resistant roots were found to be about 5-fold higher than those from susceptible roots. Six isozymes were distinguished from anionic peroxidase by anionic-exchange chromatography.