Preliminary Study On The Mechanism Of Meprofenone On The Rice Blast Fungus

Isobavachalcone(IBC)is an excellent plant-derived fungicide on the market,and it is broadly applicable to fifteen kinds of pathogenic fungi such as Valsa mali Miygabe et Yamda,Magnaporthe grisea,Colletotrichum orbiculare,Colletotrichum coccodes,and Fusarium graminearum.It has an excellent antibacterial effect,but there are few studies on the antibacterial mechanism of the fungicide on Magnaporthe grisea.In order to further study the mechanism of isobavachalcone,this paper mainly carried out by four parts.Firstly,the Magnaporthe grisea was used as the test bacteria to explore the effect of IBC on the cell wall of fungus,using ultraviolet spectropHotometry and Fluorescence spectropHotometry techology to determine the activity of chitinase and glucanase which the hydrolases of IBC,moreover the content of the corresponding hydrolysate of the two was determined.Then,the synthetases about cell wall were determined as well.The concentration of extracellular phosphorus and Fluorescence intensity of PI-DNA complex,the content of sterols in the cell membrane of Magnaporthe grisea were detected,in order to consider the interaction of IBC on membrane.Besides,though combined with molecular simulation technology by chitinase homology modeling,active site prediction,MD analysis and complex MD simulations,molecular docking and binding free energy calculation the interactions between isobavachalcone and chitinase were investigated by the.Finally,the effect of isobavachalcone on the whole protein in Magnaporthe grisea was observed by SDS-PAGE protein electropHoresis.Through the analysis of the cell wall membrane of Magnaporthe grisea and the analysis of protein,the pattern of chitinase and isobavachalcone can be concluded as that isobavachacone can regulate activity of cell wall hydrolase and partial synthetase to affect cell wall structure and function.And interact with the residues of the chitinase ASP267 and ARG276 by hydrogen bonding,and form an important hydropHobic interaction with non-polar amino acids such as TYR270,PRO271,VAL272,LEU310,PRO311,TYR316 and LEU317.It destroys the fluidity and integrity of the cell membrane and accelerates cell death to exert a bacteriostatic effect.I hope all conclusions above can provide a theoretical basis for the fungicide mechanism of iaobavachalcone and provide ideas for the development of new fungicides.