Evaluation of the lethal effect of hydrogen peroxide on the root-knot nematode, Meloidogyne javanica, and the disruption in the activity of enzymes related to its biosynthesis

Abstract

Summary In this study, the accumulation of hydrogen peroxide (H2O2) in different parts (healthy root, gall, root attached to gall, aerial parts) of healthy tomato plants and plants infected by the root-knot nematode, Meloidogyne javanica, was investigated after treating the roots with β-aminobutyric acid (BABA). In addition, the effects of different concentrations of H2O2 (0-2 mM) on mortality, body structures and the digestive system of second-stage juveniles (J2) were also investigated in in vitro experiments. Results showed that exposure to concentrations of more than 1 mM H2O2 is lethal for J2, while the digestive system is not able to tolerate concentrations of more than 0.2 mM. Evaluating the activity level of enzymes related to biosynthesis and removing H2O2 in treated plants also showed that the nematode has significant suppressive effects on the biosynthesis enzymes of this compound, and this effect is greater in the site of nematode activity than in other parts of the plant. By contrast, the activity of catalase enzyme, as one of the H2O2-removing enzymes, shows a significant increase in all parts of nematode infected plants (especially in galls).