Study On Prification And Separation Of Active Substances And Its Mechanism To Inhibit Fusarium Oxysporum In Chrysanthemum

China is the largest country in the production and consumption of watermelons in the world,and Jiangxi province is also a major province of watermelon production.Watermelon plays an important role in the adjustment of agricultural structure and the increase of farmers'income in Jiangxi province.In recent years,both domestic and foreign scientists and technicians have paid great attention to the research on the sterilizing technology of Watermelon Fusarium wilt,which is safe and non-toxic and economic and environmental.However,no ideal results have been put into production.The aim of this study is to exploit the bacteriostat produced in plants and replace chemical fungicides,and to develop plant source fungicides suitable for watermelon wilt.The main results are as follows:1?Fusarium oxysporum f.sp.was used as research object,and growth rate method was adopted to study the allelopathy on watermelon Fusarium wilt of extracts from different parts of Chrysanthemum,in order to provide reference for the separation and purification of antibacterial active components in Chrysanthemum.The results showed that the three extracts of water extract had certain allelopathic effect on the growth of Fusarium oxysporum f.sp.,and the inhibition rates were 53%,49%and 45%at 100 mg·mL^-11 treatment,respectively.There was no significant difference between the three parts according to Duncan's variance analysis.With the decrease of the concentration of the extract,the inhibition rate showed a decreasing trend.The EC₅₀ of the three parts was 86.26,84.65 and 106.88 mg·mL^-1 by indoor virulence test.The results showed that the inhibitory effects of the extract of stems and leaves were higher.2?The antibacterial substances in Chrysanthemum morifolium were separated and purified by the method of biological activity tracking,and the monomer substances with strong antibacterial activity were finally obtained.The obtained compounds were structurally identified by NMR,13C-NMR and HR-ESI-MS methods and identified as 3-o-caffeoyl quinic acid,5-o-caffeoyl quinic acid,4-o-caffeoyl quinic acid,3,4-dicaffeoyl quinic acid,1,5-dicaffeoyl quinic acid,3,5-dicaffeoyl quinic acid,4,5-dicaffeoyl quinic acid.3?In order to determine the antibiotics on F.oxysporum f.sp.from Chrysanthemum coronarium,we studied the bacteriostatic activity of3-O-caffeoylquinic acid?chlorogenic acid?which isolated from the stem and leaf tissues of Chrysanthemum.The MIC and MFC of Fusarium oxysporum f.sp.were31.25mg·ml^-1 and 125 mg·ml^-1 respectively.The EC₅₀0 of chlorogenic acid to F.oxysporum f.sp.was 53.048 mg·ml^-1 by indoor virulence.The spore germination rates of watermelon F.oxysporum f.sp.were 64%,33%and 12%at the concentrations of MIC,EC50 and MFC,while the spore germination rate reached92%of CK,the difference of spore germination rate between treatments was significant by Duncan's difference analysis.With the increase of pharmacy concentration,the hyphae and fresh weight of F.oxysporum f.sp.showed a decreasing trend.In addition,the treatment of the agent accelerated the rate of infiltration of the inner electrolyte and increased the cell membrane permeability,and lay a theoretical foundation for the research and development of new natural plant fungicides,and provide scientific for the development and utilization of chrysanthemum Basis,has important academic value and application prospects.This research can provide scientific basis for further development and utilization of Chrysanthemum,and provide a feasible experimental method and theoretical basis for the screening of other natural antibacterial active ingredients and the study of the mechanism of bacteriostasis,which has important academic value and application prospect for research and development of new natural plant source fungicides.4?The inhibitory mechanism of chlorogenic acid solution(MIC,EC₅₀,MFC)on Fusarium oxysporum was studied using Watermelon Fusarium oxysporum as indicator strain.The results showed that after chlorogenic acid,EC50,Watermelon Fusarium oxysporum mycelium and cells showed different degrees of damage,mycelium thickness varies,the emergence of local four depression,even dry sores,severe crack formation,the mycelial growth of mycelium degeneration,cell wall thickening,protoplast shrinkage,plasmolysis,vacuoles phenomenon,some mycelia cell cavity,organelle disintegration,plasma electron density decreased with increasing;chlorogenic acid concentration,the enzyme activity of succinate dehydrogenase and malate dehydrogenase of Watermelon Fusarium oxysporum were significantly decreased,and the significant differences between treatment and treatment effect showed that chlorogenic acid the metabolic pathways of the cell,inhibit the normal growth;in the concentration of MIC,EC50,MFC,catalase activity was significantly reduced;in addition,chlorogenic acid treatment can make Large molecules of bacteria-proteins and nucleic acids-are largely extravasation.