The reactive oxygen species are involved in resistance responses of wheat to the Russian wheat aphid

The effect of Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), infestation on the hydrogen peroxide (H 2O 2) content and NADPH oxidase (EC 1.6.3.1) activity was studied in the resistant (cv. Tugela DN) and near-isogenic susceptible (cv. Tugela) wheat ( Triticum aestivum L.). The objective of this study was to investigate the involvement of the reactive oxygen species (ROS) during the resistance responses against the RWA. Infestation significantly induced an early accumulation of the H 2O 2 and increase of NADPH oxidase activity to higher levels in the resistant than susceptible plants. Results of inhibitory studies using diphenylene iodonium (DPI), a suicide inhibitor of NADPH oxidase, strongly suggested a possible signalling role for H 2O 2 during RWA resistance response by activation of downstream defence enzymes [intercellular peroxidase (EC 1.11.1.7) and β-1,3-glucanase (EC 3.2.1.39)].