Screening And Extraction Of Antiviral Polysaccharide Against Tobacco Mosaic Virus

As an important economic crop in China, tobacco is quite a remarkable plant inagricultural production. But pests caused serious losses every year, thus, the pests controllingworks are regarded as a study emphasis by agronomic researchers. Being one of the maindiseases of tobacco, it has brought great loss and hard to control. Nowadays, the maincontrolling methods for this disease is chemical pesticide treatment. However, the largenumber of long-term use of chemical pesticides has led to serious environmental and foodsafety issues, thus, the use of chemical pesticides should be reduced, and the principle“Prevention-oriented, integrated control” shall be put into application. This research aimedat screening the polysaccharide with strong antagonism against tobacco mosaic virus, andinvestigation on its affect on tobacco growth, Optimization its fermentation extractionconditions to get a new microbial pesticide resources against tobacco mosaic virus.In this research, four polysaccharides with strong antifungal activity was screened from12kinds of polysaccharides by half leaf method on Nitcotiana tabacum var. Samsun NN, andthey are Coriolus versicolor polysaccharides（CVP）, Armillaria mellea polysaccharides,Cordyceps sinensis polysaccharides and Grifola umbellata polysaccharides. The fourpolysaccharides that were inoculated after treated for48h had a good inhibition effect onTMV, and the inhibition effect of CVP even reach in92.12%. CVP also had a visible controleffect on virus diseases （TMV, CMV and PVY） in tobacco NC-89, which the highestefficiency against these virus diseases was above50%. Especially, the efficiency on TMV wasthe best, and the efficiency would up to65.25%while the concentration was2.0g/L. And wefound that CVP could delay the onset of virus diseases. So, CVP was beneficial for tobaccogrowth.The growth-promoting of CVP on tobacco was found by greenhouse and plot experiment.After treated by polysaccharides, the tobacco with dark green and smooth leaves lookedrobust and tidy. Comparing with the control, fresh weight and area of maximum leaf oftobacco seedling dealt with1g/L CVP were increase of30.98%and19.74%respectively.Even more, plant height, stem circumference, yield and superior rate of tobacco dealt with1g/L CVP were increase, and the superior rate tobacco had an increase of17.20%. The experimental results showed that the medium types, medium volume and incubationtime had a affect on mycelium production. The mycelium dry weight in types②was as theheaviest as1.241×10^-2g/mL, and smaller liquid volume was good for Coriolus HZ-186growth. Moreover, incubation time had a significant affect too, which the mycelium dry weightwas the heaviest on the8th day before they decline.In addition, through the one-factor and orthogonal test, extraction time, extractiontemperature and solid-liquid ratio were positively correlated with the polysaccharides yield.Extraction temperature and extraction time made significantly impact on the polysaccharidesyield, and polysaccharides yield increased significantly at50℃to80℃. Besides, the additionof polysaccharides yield slowed when the extraction time went to5h. With the solid-liquidratio increased, the addition of polysaccharides yield reduced gradually. The final optimumconditions for extracting obtained was A₂B₃C₃, i e the solid-liquid ratio as1:20, extraction time for5h, extraction temperature of95℃.