Effects of feeding Clostera anachoreta on hydrogen peroxide accumulation and activities of peroxidase, catalase, and ascorbate peroxidase in Populus simonii × P. pyramidalis ‘Opera 8277’ leaves

In response to Clostera anachoreta larvae attack, poplar ( Populus simonii × P. pyramidalis ‘Opera 8277’) leaves produced a high level of hydrogen peroxide (H 2 O 2 ). Histochemical localization revealed that H 2 O 2 was mainly localized in herbivore-wounded zones and might spread through the veins. The activities of three H 2 O 2 -scavenging enzymes, i.e., peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT), were also enhanced in herbivore-wounded leaves, and exhibited an opposite pattern to the accumulation of H 2 O 2 . It was found that diphenylene iodonium chloride (DPI, a special inhibitor of NADPH oxidase) treatment significantly inhibited the accumulation of H 2 O 2 induced by herbivory damage. Moreover, DPI treatment led to an obvious decrease in the activities of POD, APX, and CAT. The results indicated that NADPH oxidase contributed to the accumulation of H 2 O 2 and the increase in activities of H 2 O 2 -scavenging enzymes in poplar leaves induced by herbivory damage. The balance between H 2 O 2 -production pathway and H 2 O 2 -scavenging enzymes led to the tolerable level of H 2 O 2 acting in P. simonii × P. pyramidalis ‘Opera 8277’ cuttings in response to herbivory damage.