| The Lysurus mokusin is a large-scale fungus that is widely distributed in China and is considered to be toxic.It has been proved that the L mokusin and insecticidal efficacy are still in the preliminary research stage.Based on the related research,this paper-conducts further experimental research on the liquid fermentation culture,antifungal effect,antifungal mechanism and toxicity of L.mokusin,results are shown as followed:(1)Optimization of liquid deep fermentation conditions of L.mokusin,The dry weight of mycelium is used as an evaluation index,and the four factors including culture temperature,pH value,inoculum volume and shake flask volume are optimized one by one.The optimized conditions for the submerged fermentation of the L.mokusin were as follows:the temperature was 25?,the pH was neutral,the volume of each shake flask was 220 mL,and the inoculum was 3 pieces of mycelium.The dry weight of the mycelium of each shake flask was increased from 0.30 g to 0.66 g by optimization of fermentation conditions.(2)The extract of L mokusin has an inhibitory effect on Botrytis cinerea,and the inhibitory effect increases with the increase of extract concentration.When the concentration reaches 16 mg/mL,the inhibition rate is 88.76%.After analysis,the virulence regression equation was:Y=1.246X-0.805,R2=0.912,and the EC50=4.428 mg/mL,the 95%confidence limit was 2.238?13.673 mg/mL.(3)The antifungal mechanism of L mokusin extract on Botrytis cinerea showed that the effect of extract on B.cinerea was multifaceted.The extract has an effect on the activity of five life activities related to B.cinerea,such as superoxide dismutase(SOD),peroxidase(POD),polyphenol oxidase(PPO),pectinase.The activity of Pectinase and cellulase(CL)decreased,and the inhibition rate of SOD and PPO activity on the 2nd day reached 65.48%and 53.86%,respectively.The inhibition effect of POD reached the peak on the 4th day,and the inhibition rate was 68.65%.(4)The extract had a destructive effect on the cell membrane of B.cinerea,resulting in enhanced cell membrane permeability and increased MDA content.The conductivity of the culture medium and the MDA content of the mycelium at each sampling time were significantly higher than that of the control.The second day conductivity of the treatment was 1230.579 ?s/cm,which was 1.3 times of the control conductivity,and the MDA of the 6th day was 2.6 times that of the control.Exogenous sorbitol was added for the Fungi test to prove the glucosporinase.The cell wall of the bacteria was destroyed;the results of the microscopic observation of the hyphae of B.cinerea showed that the extract changed the morphology of the hyphae,the hyphae dried up,the hyphae were recessed,and the hyphae ruptured.(5)The L.mokusin extract as a protective agent has a significant effect on B.cinerea of tomato fruit.When the extract concentration reaches 64 mg/mL,the lesion control rate can reach 74.79%,although the concentration is as high as 128 mg/mL.There was no fruit damage and toxicological damage caused by extracts in/mL;the extract had a significant effect on the 24 germination rate and 72 h germination rate of Vigna radiata(Linn.)Wilczek seeds,that is,the extract had certain toxic effects on mung beans;the extract on zebrafish The acute toxicity test showed that the extract was low toxicity to aquatic Danio rerio with an LC50 of 426.54 mg/L. |
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