Changes in defense-related enzymes and phenolics in resistant and susceptible common wheat cultivars under aphid stress

Abstract The cereal aphids Rhopalosiphum padi L. are serious pests on grain crops, reducing the quality and yield by direct feeding damage virus transmission. changes in physiological biochemical parameters of two wheat cultivars under aphid stress were investigated to understand aphid-resistance mechanisms. activity levels phenylalanine ammonia-lyase (PAL), peroxidase (POD), tyrosine (TAL), Ca 2+ -ATPase Mg resistant cultivar W0923 increased during feeding, most them significantly higher than those susceptible GN21. However, these enzyme activities then decreased polyphenol oxidase (PPO) was maintained longer total phenol contents exhibited significant increases 15th day compared with untreated controls, content GN21 30th day. Most POD, PPO, PAL, TAL phenolic metabolite control conditions. PAL positively correlated PPO activities. may be key markers for evaluating resistance. had a strong ability maintain synthesize more phenols tannins GN21, which contributed