With the improvement of people's awareness of environmental protection and the progress of scientific research and technology,the development of fungicides based on natural products is attracting increasing attention.Glabridin is a kind of flavonoids isolated from licorice root.In previous study,it was found that glabridin has obvious antifungal activity against a variety of plant pathogens,especially on Fusarium graminearum.Therefore,the paper systematically studied the effects of glabridin on cellular structure and physiological metabolism of F.graminearum.In addition,TMT technology was used to analyze the differential proteome of F.graminearum,in order to further clarify the action target of glabridin from the molecular level and provide reference for the analysis of the inhibition mechanism of glabridin on F.graminearum.The main results are as follows:1.The bioactivity of glabridin against F.graminearum was studied.In vitro activity assay showed that the EC50of glabridin inhibiting the mycelial growth of F.graminearum was 110.70 mg/L and the EC50of glabridin inhibiting the conidial germination of F.graminearum was 40.47 mg/L.The semi-living assay of wheat heads showed that the control efficiency of 200 mg/L glabridin was 76.95%,and only a small area of scab symptoms were observed around the conidial inoculation area of the wheat heads after treatment with glabridin,so that the symptom of FHB caused by F.graminearum was improved obviously.The field assay showed that the control efficiency of 90%glabridin powder 180.0 ga.i/hm2was 63.18%.2.The effects of glabridin on cellular structure and physiological metabolism of F.graminearum was studied.Through scanning electron microscopy,it was found that the mycelia morphology changed after treatment with glabridin on F.graminearum,the mycelium was depressed collapsed,the growth point was broken and the morphology was damaged,resulting in the cell contents exosmosis,which caused mycelia to appear different degrees of shriveling,deformation and even death.Physiology and biochemistry assay showed that the permeability of cell membrane of F.graminearum increased significantly,the cell membrane depolarized,the integrity of membrane was destroyed,the content of ergosterol decreased,and there was a significant positive correlation with the concentration of glabridin.The respiration rate of F.graminearum mycelia treated with glabridin of different concentrations was measured by dissolved oxygen meter,and the results showed that glabridin had a significant inhibition effect on the energy metabolism of F.graminearum.3.TMT was used to study the proteome of F.graminearum.The results showed that381 proteins of F.graminearum treated with glabridin were different,among which 186were up-regulated and 195 were down-regulated.The enzymes related to material synthesis and metabolism,such as oxidoreductase,phosphatase and lyase,were affected,the membrane structure was destroyed,mechanically sensitive ion channel protein related to transmembrane transport and ERG24 related to ergosterol synthesis were blocked,and the butanoate metabolism pathway related to energy metabolism was abnormal,such as succinate-semialdehyde dehydrogenase,which was significantly down-regulated.4.It is speculated that the mechanism of glabridin inhibiting F.graminearum was as follows:acts on membrane associated proteins,causes the synthesis of ergosterol was blocked,damage the cell membrane,destroys the integrity of membrane structure,causes the abnormal transmembrane transport,exosmosis of cytoplasm and the rise of membrane potential,thus affects the activity of intracellular enzymes,causes the disorder of material synthesis and metabolism,impedes the respiratory process and inhibits the energy synthesis.At last,the mycelia of F.graminearum was seriously deformed,cell membrane was broken,growth and development were inhibited,even died. |