The involvement of reactive oxygen species in the resistance response of wheat to the Russia wheat aphid

[摘要] English: The effect of Russian wheat aphid (RWA), (Diuraphis noxia, Mordvilko),infestation on the activities of the reactive oxygen species (ROS) generating andscavenging enzymes as well as the hydrogen peroxide content were studied inresistant (cv., Tugela DN) and the near isogenie susceptible (cv., Tugela) wheat(Triticum aestivum L.) cultivars. Infestation resulted in an early induction (6-9hafter infestation) of the activities of the ROS generating enzymes, NADPH oxidaseand superoxide dismutase (SOD), in resistant plants only. These increased enzymeactivities correlated with the increased H202 content in infested resistant plants. Theactivities of the ROS scavenging enzymes, glutathione reductase and ascorbateperoxidase were selectively induced somewhat later (12h after infestation) inresistant plants. Results suggest art early involvement of the ROS, and relevant ROSgenerating and scavenging enzymes in the resistance response of wheat to theRWA.Inhibitory studies were performed in vivo using diphenylene iodonium (DPI), aninhibitor of NADPH oxidase, to shed light on the possible upstream role ofROS indefence against the RWA in infested resistant plants. DPI substantially inhibited theRWA induced NADPH oxidase activity and the concomitant accumulation of H202.This resulted in the inhibition of activities of the secondary defence relatedenzymes, β-1,3-glucanase and peroxidase, suggesting a signaling role for H202 inRWA resistance through activation of defence genes. Accordingly, treatment ofplants with the H202 generating mixture of glucose and glucose oxidase resulted ininduction of the H202 production as well as induction of the β-1 ,3-glucanase andperoxidase activities in resistant plants.In vitro inhibition studies confirmed that DPI is a specific inhibitor of NADPH oxidaseand did not have any direct inhibitory effect on the β-1 ,3-g1ucanase andperoxidase activities. This finding further substantiated that H202 generated duringRWA infestation was involved in the signaling events leading to induction of thesecondary defence responses in resistant plants.

[发布机构] University of the Free State