Study On The Antifugal Effects Of Lansiumamide B

Clausena lansium?Lour.?Skeels belongs to the rutaceae plant,which is mostly produced in south China.It has been planted in China for more than 1500 years.The existing research proves that the isolated from Lansiumamide B the nucleus of the Clausena lansium has bactericidal activity,but its research is not systematic.In this paper,the antimicrobial spectrum of Lansiumamide B was systematically determined by laboratory bioassay,and the experiments in pot and in vitro were carried out.The bacteriostatic mechanism of Lansiumamide B was preliminarily studied by Rhizoctonia solani.The results are as follows:1.The mycelial growth rate method was used to determine the virulence of Lansiumamide B to the mycelial growth of various plant pathogens.the showed that Lansiumamide B had good bacteriostatic activity against more than ten kinds of plant pathogenic fungi.Lansiumamide B had the best effect on Rhizoctonia solani,Botrytis cinerea and Sclerotinia sclerotiorum,with EC₅₀ of 2.99?g/mL,10.98?g/mL and 4.30?g/mL,respectively.Based on the results of laboratory bioassay,the experiment was carried out in vivo.The results of in vivo and pot experiments showed that 800?g/mL of Lansiumamide B had good control effect on Rhizoctonia solani,Botrytis cinerea and Sclerotinia sclerotiorum.However,the control effect of Lansiumamide B on obligate parasitic Blumeria giamiaiais was not good.2.SEM observation showed that Rhizoctonia solani without Lansiumamide B treatment had full hyphae,fine hyphae,uniform branches and smooth surface.After treatment with 5?g/mL Lansiumamide B,mycelia showed obvious irregular expansion,abnormal growth point,slow and disorderly growth rate of mycelia,and most of the mycelia collapsed,with intravenous extravasation.Transmission electron microscopy showed that the mycelia without Lansiumamide B treatment had regular cell morphology,complete structure,uniform and dark cell wall,uniform distribution of protoplasm,clear visible nucleus,and clear structure of cell membrane and organelle membrane.After treatment with 5?g/mL Lansiumamide B,the cell wall showed irregular damage,the nuclear structure was not clear,there was no obvious nuclear membrane boundary,the organelle was fuzzy,the organelle membrane structure was incomplete,some organelles contained extravasation,and cavity appeared.3.The electrical conductivity of different concentrations were Lansiumamide B of Rhizoctonia solani is the influence of the cell wall membrane permeability,found that the different concentration of Lansiumamide B handle pathogen relative conductivity significantly higher than the untreated relative electric conductivity,and with the higher drug concentration,the greater the relative conductivity,after 3 hours,medicament treatment conductivity increased significantly.Liquid phase oxygen electrode was used to determine the effect of Lansiumamide B on mycelial respiration of Rhizoctonia solani.After treatment with different concentrations of Lansiumamide B,The content of chitin decreased by24.08%,40.03%and 55.00%,respectively.The content of extracellular polysaccharides increased by 11.40%,12.04%and 15.64%,respectively.After treatment with low concentration?2.5,5.0?g/mL?of Lansiumamide B,the content of reducing sugar decreased by 4.50%and 15.20%,respectively,compared with the control group.After treatment with high concentration?10.0,20.0?g/mL?,the content of reducing sugars increased by 44.03%and 96.52%,respectively,compared with the control group.In addition,Lansiumamide B also had a certain effect on the sclerotium production of Rhizoctonia solani.Low concentration treatment can stimulate sclerotium production,high concentration treatment can inhibit sclerotium production.In the absence of drug treatment,the sclerotium is generally generated at the edge of the petri dish.After drug treatment,the sclerotium is gradually close to the center of the dish.To sum up,the antibacterial spectrum of Lansiumamide B was determined in this study,and the pot experiment was carried out to determine the better control effect of Lansiumamide B on Rhizoctonia solani,Botrytis cinerea and Sclerotinia sclerotiorum.Rhizoctonia solani was selected as the research object,and the effects of Lansiumamide B on Rhizoctonia solani were preliminarily investigated by scanning electron microscopy and transmission electron microscopy,combined with physiological and biochemical results,in order to destroy the structure of its cell membrane,thus affecting its material absorption and utilization,and interfering with the cell metabolism process.This study provides a basis for the future development and utilization of Lansiumamide B as a biogenic pesticide,and lays a foundation for its mechanism and provides some ideas for the follow-up research.