Abstract: Abstract:【Object】 study the mechanism of induced resistance by the feeding of Rhopalosiphum padi on 5 Aegilops species and explore synergical resistance of PPO and POD to aphid and the feasibility of resistance evaluation according to necrosis area on the leaf damaged by aphid.【Method】determination the content of gramine by TLC and the enzyme activity of PPO, POD and PAL by UV spectrophotometer, calculation the necrosis area by PHOTOSHOP 7.0【Result】necrosis areas on the leaf of these species which had different resistance levels were positively related to the number ratio of aphid(r=0.951**). The increase ratio of Polyphenol Oxidase,Peroxidase and Phenylalanineammonia-lyase activities were negatively related to the number ratio of aphid(r=－0.824,－0.856 and－0.754, respectively). 56.37％ correlation between the increase ratio of PPO activity and the number ratio of aphid was synergied by POD. Conversely, 46.85％ correlation happened to POD was done by PPO. The constitutive contents of gramine were not significantly related to resistance to aphid in the plants; but after feeding by aphid, its contents showed variability significance and its increase ratio was negatively related to the number ratio of aphid, necrosis area significantly(r=0.884*,－0.953*, respectively).【Conclusion】 New method for evaluating resistance was figured out according to necrosis area on the leaf damaged by aphid, PPO and POD were synergied each other in resisting to aphid in Aegilops. The content of gramine could prevent from the population growth of Rhopalosiphum padi.

Key words: Aegilops, Rhopalosiphum padi, induced resistance, oxidase, synergy