Cotton Defense Response Stressed By Aphis Gossypii And The Effect Of Medicaments On Defense Stress Enzyme Activity Of Aphis Gossypii

Aphis gossypii is an important phytophagous piercing-sucking pests, widely distributed all over the world. It harmed many plants include cotton, pumpkin, watermelon. Xinjiang is main cotton producing areas, the occurrence of Aphis gossypii seriously affects the yield and quality of cotton. This paper used 5-6true leaves stage of Xinluzhong 37 and 1-2 age Aphis gossypii as study objects, determined the activity of defense enzyme(catalase CAT, peroxidase POD, polyphenol oxidase PPO, lipoxygenase LOX,Phenylalanine ammonia-lyase PAL) in cotton leaves, nutrients in cottons, secondary metabolites and expression of related defense genes after cottons being fed and induced by the Aphis gossypii at 24 h, 48 h,72h, 96 h, determined the activities of three kinds of protective enzymes(superoxide dismutase SOD,catalase CAT and peroxidase POD) and three kinds of detoxifying enzymes(carboxylesterase CarE,glutathione-s-transferase GSTs and acetylcholinesterase AchE) in internal Aphis gossypii after different medicament spraying. The aims is to provided a new theoretical basis for integrated control of Aphis gossypii and Aphis gossypii resistant varieties. The main results were as follows:1. Effect of Aphis gossypii Feeding on Defense Enzyme ActivityWith the prolonging of Aphis gossypii feeding time, activities of CAT, POD, PPO, LOX and PAL in cotton leaves all increased at different degrees in early damage stage. With the increase of Aphis gossypii feeding density, CAT, POD, PPO, LOX and PAL activities in cotton leaves had an increasing trend. CAT activity of treatment group was all higher than the control groups, and the activity of CAT all reached maximum value at 72 h. Activity of PPO increased, the activity of PPO showed peak changes, and reached maximum value at 48 h or 72 h. LOX activity of each group all had significant difference in time, all reached maximum value at 72 h, and was significantly higher than that of 24 h, 48 h and 96 h. There was significant difference in PAL activity among all treatment groups at 24 h.2. Effect of Aphis gossypii Feeding on Expression of Related Defense GenesWith the prolonging of Aphis gossypii feeding time, expression amount of cat、pod、ppo and pal genesall increased at a certain extent in early damage stage. Cat gene expression amount of control group was higher than 10, 20, 30 and 40 heads treatment groups at 24 hours. Pod gene and ppo gene of all the treatment groups did not have significant difference at 96 h. Pal gene expression amount of all the treatment groups did not have significant difference at 24 h and 96 h, 30 heads treatment group was significantly higher than other treatment groups at 48 h, 40 heads mixed populations treatment group was significantly higher than control group, 10 heads treatment group and 20 heads treatment group at 72 h.3. Effect of Aphis gossypii Feeding on Chlorophyll, Nutrients and Secondary MetabolitesWith the prolonging of Aphis gossypii feeding time, the content of soluble sugar, soluble protein and phenolic compounds in cotton leaves all increased at different degrees in early damage stage. With the prolonging of feeding time, chlorophyll content of treatment group decreased. With the increase of Aphis gossypii feeding density, the content of soluble sugar, soluble protein and phenolic compounds in cotton leaves had an increasing trend. Soluble sugar content of all treatment groups had significant difference in time. Soluble protein content of control group, 20 heads treatment group, 30 heads treatment group, 40 heads treatment group and 40 mixed treatment group all differed significantly in time, there was significant difference in 10 heads treatment group. The phenolic compounds content of control group and 10 heads treatment group reached maximum value at 96 h, phenolic compounds content of 20 heads treatment group,30 heads treatment group, 40 heads treatment group and 40 heads mixed populations treatment group reached maximum value at 72 h.4. Effect of Acetamiprid and Amino Oligosaccharin on Activity of Stress Defence Enzyme of Aphis GossypiiSOD, CAT and POD activity in internal Aphis gossypii all had a inhibition trend in initial stage of Acetamiprid and 5% Amino Oligosaccharin treatment after aphid gossypii fed the cotton. Car E activity behaved as inhibition effect at first, activation effect and inhibition effect at last within 96 h, and there were activation effect on GSTs and AchE activity.