Studies On Induced Resistance Mechanism Of Chitooligosaccharides From Housefly Larvae To Tobacco Blank Shank

The inhibitory activity and induced resistance of Chitooligosaccharides fromhousefly larvae to tobacco black shank, Phytophthora parasitica var. nicotiana, weretested. Under the artificial inoculated conditions, Determination of several defensiveisozyme activity, and using vertical slab polyacrylamide gel electrop- horesis (PAGE)analysis of the tobacco plants sprayed with Chitooligosaccharides after isozymezymography changes; Meanwhile on lignin and phenolic content and anti-black shanktobacco disease were studied, proven to Chitooligosaccharides on tobacco black shankdisease biocontrol effect and mechanism, the main findings are as follows:Chitooligosaccharides's influence on mycelial's growth rate, morphology and SporeProduction capacity is obvious; The test showed that Chitooligosaccharides inhibits themycelial'growth and different concentrations of Chitooligosaccharides's dampening effects aredifferent. Within a certain extent, with Chitooligosaccharides concentrations increased,inhibition rate has correspondingly increased. 1.0mg/ml of Chitooligosaccharides has the mostsignificant inhibitory effect, after 7 days of experiments,the ratio of the inhibitory effect is96.0ï¼…. Chitooligosaccharides have great impact on the mycelium and sporulation ability,caused distortions small and branch expansion of the mycelium, while zoosperm productivity isalso inhibited, so as to inhibit the growth, reproduction and infection of the fugus.The diseases tobacco seedlings sprayed Chitooligosaccharides after inoculation havesignificantly reduced. Meanwhile tobacco leaves' phenylalanine ammonia-lyase (PAL),Peroxidase (POD) and polyphenol oxidase (PPO) activity increased to varyingextent, respectively, reaches the peak in 8 days, 5 days and 3 days which are higher thanthat of the controls of 94.62ï¼…, 160.44ï¼…and 89.76ï¼…respectively. Further analysis of thezymography of POD, PPO isoenzyme, the plants which are inoculated after sprayingChitooligosaccharides have more enzyme bands and are also deeper in the color. Studyshow that Chitooligosaccharides have great relationship with the inducement of severaldefense-related enzyme.We evaluated the lignin content and phenolic substances inside the tobaccoseedlings which are sprayed Chitooligosaccharides, the results indicate that after sprayedthe Chitooligosaccharides, lignin and phenolic content are significantly higher than thecontrols, These changes in the relationship between different sampling time beforeand after the results consistent. This shows tobacco seedlings sprayed with Chitooligosaccharides enhance cell wall and the degree of lignification of the accum-ulation of phenolic substances, Branch-induced increase of black shank tobacco diseaseresistance response, disease resistance physiological and biochemical mechanism of clear,Chitooligosaccha- rides to prevent application of the practice of laying the foundation.The results of this study show that the Chitooligosaccharides can inhibited thePhytophthoraparasitica var. nicotiana's growth. At the same time the tobacco plants canbe induced to black shank resistant to the fungus. This is related with defense-relatedenzyme, lignin and phenolic content of the materials. The results offered theoreticalevidences for further revelations of the physiological and biochemical mechanism of theChitooligosaccharides's inducement of the resistance inside the tobacco seedlings, andalso provides new ideas and methods to control tobacco black shank disease.