Studies On Action Mode Of Saponins From Schima Superba Resisting Rice Blast Pathoen

The active substance resists the rice blast fungus, which we named "active saponin fromSchima superba " was extracted by Biological separation material laboratory of JiangxiAgricultural University. Research has shown that active saponins has a strong inhibitoryeffect on resists the rice blast fungus, and had the potential of developing plant-basedfungicide. To identify action mode of saponins from Schima superba resistingMagnaporthe oryzae,this thesis mainly studied from determination of active saponinresists the rice blast fungus, the morphological changes of mycelium were observatedunder microscope and the Pathogenic bacteria protoplast morphology changes; Then onthis basis, determination of a series of cell physiological indexes. As to research in theeffect of all active saponins from Schima superba on rice blast bacteria cell wall and cellmembrane. Here are the main research methods and results:(1)The activities anti-blast pathogen mycelia of MIC and MBC were determinatedusing96-well plate method, The results showed that active saponins from Schima superba wereshowed a greater resistance to rice blast fungus, The MIC values of M2IGR5R3were6.25μg/mL, and it can kill99.5%of the original access Magnapor the grisea when the valuesis12.50μg/mL. The MIC values of M2IGR5R1,M2IGR5R2,M2IGR5R4,M2IGR5were56.25、25、14.0625、12.50μg/mL;The MBC values of them were225、25、112.5、50μg/mL.The toxicities of precipitates of M2IGR5R3were the strongest and had the potentialof developing plant-based fungicide.(2)After treated with active saponin from Schima superba through the cellwall staining experiments, we found that the active saponin from Schima superba had acertain impact on M. oryzae cell wall, It can lead to cell wall of irregular shape, uneventhickness, fuzzy staining, even no cell wall integrity. On this basis；Further determinationof fungal cell wall synthesis on N-acetyl glucosamine content and chitinase activity, wefound N-acetyl glucosamine content and chitinase activity had a certain degree of increasewhile treated with active saponins from Schima superba:The drug treated mycelium N-acetyl glucosamine content was1.46~1.86times than control group at the same time, thedrug after mycelial chitinase activity is1.4~2.1times of control group at the same time.Byinference: active saponins from Schima superba may lead to leakage in the mycelium ofglucose or hinder the absorption of glucose in mycelium, and then stimulatedthe chitinase gene expression, and hydrolyzed chitin to N-acetyl glucosamine, ledto abnormal cell wall growth.(3)To identify action mode of saponins from Schima superba resisting M. oryzae. Weuse lysing enzymes to remove the cell walls of rice blast, The results showed that protoplast variant, adhesion and cracked; Further determination of conductivity, solublesugar and protein content of the mycelial culture liquid treated with action mode ofsaponins. It turned out that Mycelium fracture, cell swelling, protoplast variant, adhesionand cracked, leakage of the cell containing substances such as protein, soluble sugar,electrical conductivity increase appeared and chitinase activity was enhanced inducedparticles of N-acetyl glucose amine from cell wall. The effective concentration for90%of Schima superba active saponin M2IGR5R2treated mycelium2h soluble proteinleakage volume reached452.0568μ g/g, up to12times higher than in the control group,the relative membrane permeability reached48.9795%, as the control group at the sametime more than1.63times, the soluble sugar leakage quantity is4.42times more than thecontrol group at the same time.Comprehensive analysis of the above results, we infered that the action of saponinsof Schima superba to M. oryzae not only in cell membranes, but also in cell wallindirectly, promote the vacuolar organelle releases such as chitin hydrolysis etc.,cause thecollapse of the cell wall.May also directly interact with nuclear genetic materialDNA.increase chitinase activity, cell wall degradation, Touch the chitinase relatedenzyme machine, produce chitinase, degradation of the chitin,further acceleratemycelium apoptosis of M. oryzae,which play antifungal effect.