Studies On Pesticide Formulation Of Coriolus Versicolor Polysaccharide And Its Effect On Wheat Yellow Dwarf Disease

Wheat yellow dwarf is a kind of virus disease caused by Barley yellow dwarf virus（BYDV）which only transmitted by wheat aphids.The average annual yield loss of wheat field affected by this disease is up to 40%,output could be lost as much as 70%if the damage is severe,causing serious economic losses to wheat.At present,wheat yellow dwarf disease is mainly controlled by chemical agents,which costs a lot of money and have a negative effect on environment and food security.Therefore,from the point of view of inducing wheat to enhance its resistance to disease,it is of great significance to develop a new microbial source pesticide to control yellow dwarf disease effectively.In order to develop a microbial source pesticide with stable structure,high antiviral activity,low toxicity and good environmental compatibility.Previous study of our laboratory proved that Coriolus versicolor polysaccharide had antiviral activity.The response surface method is adopted for liquid fermentation condition optimizing firstly,satisfying the efficiently express of Coriolus versicolor polysaccharide active substances,to carry out pharmaceutical development and efficacy determination.It is preliminary work for drug development and industrialization of virus disease prevention.The main results are as follows1.6 strains were obtained after isolation and purification,and 2 active strains of Coriolus versicolor were identified through observation of colony culture characteristics,morphological identification of mycelia and molecular identification.We named them YZ5and YZ6.2.To improve the polysaccharide production from Coriolus versicolor,medium component of submerged fermentation was optimized using single factor and orthogonal design experiments:brown sugar 40g/L,yeast extact3g/L,tryptone2g/L,K₂HPO₄ 2g/L,KH₂PO₄ 2g/L,MgSO₄ 1.5g/L,peanut oil 1%（v/v）.Single factor and response surface methodology were carried out to determine the optimal fermentation conditions.The optimized conditions were as follows:initial pH6.5,loading volume 100mL/250mL,inoculation of 10%,temperature 27℃,7d,200 r/min.The biomass and exopolysaccharide production under optimized fermentation processes were 10.82g/L and 1.98g/L.Compared with production before optimization,the biomass was increased by 2.06 times and the exopolysaccharide production was increased by 2.33 times.3.According to the quality requirements of biological source pesticide,5%,7%,10%of polysaccharide peptide emulsion and water were prepared.The test results show that the 5%and 7%concentrations of the agents have good stability at low temperature and heat condition.Through the experiment of half leaf spot method on tobacco,it was found that the agent of Coriolus versicolor polysaccharide had a significant effect on TMV,especially a good inhibitory effect on the initial infection of TMV and the virus proliferation after infection.In a word,the protective effect of Coriolus versicolor polysaccharide is better than its therapeutic effect.4.Through the indoor and field control effect measurement,we found that the polysaccharide pesticide had a significant effect on the control of wheat yellow dwarf disease,which could provide a new choice for the for the application of green prevention and control of wheat yellow dwarf disease.