Study On The Antifungal Activity Of Artemisia Annua Extracts Against Four Plant Pathogenic Fusarium

Fusarium is one of the main pathogenic fungi causing field crop diseases,which does great harm to agricultural production.Effective biological control of plant diseases caused by Fusarium is of great significance to the high-quality development of agriculture in China.Studies have shown that the extract of Artemisia annua(volatile oil and water extract)has a broad-spectrum antifungal activity and has a significant inhibitory effect on a variety of pathogenic microorganisms.Using Artemisia annua as a raw material for industrial extraction and production of artemisinin produced a large number of oily residues and medicine residues,which have not been effectively used,resulting in a great waste of resources and environmental pollution.Based on the dual requirements of botanical bio-pesticide development and the resource utilization of artemisinin extraction wastes,on the basis of studying the biological characteristics of four common plant pathogenic Fusarium(F.oxysporum,F.solani,F.verticillium and F.graminearum),the chemical constituents of Artemisia annua essential oil(AEO)and artemisinin extract residual essential oil(AREO)were analyzed by gas chromatography-mass spectrometry(GC-MS).The antifungal activity of AEO and AREO against Fusarium was determined by mycelium growth rate method.The antifungal mechanism of Artemisia annua extract on Fusarium was explored by measuring the change of cell membrane permeability,intracellular leakage and scanning electron microscope observation,and the molecular mechanism of AREO inhibiting the growth of F.graminearum was analyzed by transcriptome sequencing technique.The main results are as follows:(1)Study on the biological characteristics of four species of Fusarium: optical microscope observation showed that F.oxysporum and F.verticillium began to produce falcate conidia on the 5th day,while F.solanum and F.graminearum did not produce spores.but its hyphae have more mycelium branches.Urea had a significant inhibitory effect on Fusarium,and the inhibitory effect on F.graminearum was the most obvious.When the concentration of urea was 7.0 mg/m L,F.graminearum stopped growing;Temperature had a significant effect on the growth of Fusarium,and too high(35?)or too low(20?)would inhibit its growth;F.graminearum has the strongest performance in producing cell wall degrading enzymes.(2)The chemical composition and antifungal activity of AEO and AREO: the content of camphor in the two extracts was the most,which both had strong inhibitory activity against Fusarium,and the effects are equivalent.When the concentration of AEO is 3.0 ?L/m L,the absolute inhibition rate of the four species Fusarium is above67%;when the concentration of AREO is 4.0 ?L/m L,the inhibition rate is above 66%;The study of antifungal mechanism shows that AREO can exert antifungal activity by changing the permeability of Fusarium cell membrane,resulting in the leakage of intracellular charged substances,nucleic acids and proteins.(3)Study on the antifungal activity and mechanism of camphor against Fusarium:in view of the fact tha camphor is the main component of AEO and AREO,its antifungal activity and mechanism were investigated and evaluated.The results showed that camphor had a significant inhibitory effect on the growth of Fusarium,and the absolute inhibition rate was above 82% when the concentration was 2.0 mg/m L;camphor inhibited the growth of Fusarium by destroying cell membrane,increasing cell membrane permeability and releasing the intracellular important biomolecules;The antifungal activity of AEO and AREO was directly related to camphor they contained.(4)The mechanism of inhibition of F.graminearum by AREO was analyzed based on transcriptome: after F.graminearum was treated with 4.0 ?L/m L AREO for 12 h,a total of 1 063 differentially expressed genes were found,including 549 up-regulated genes and 514 down-regulated genes.The results of GO functional enrichment analysis showed that the differential genes were mainly distributed in a variety of functions,such as catalytic activity,metabolic process,membrane and binding and so on.KEGG enrichment analysis showed that differential genes were mainly involved in metabolic pathways,biosynthesis of secondary metabolites,carbon metabolism and ribosomes,and the inhibitory effect of AREO on F.graminearum was a synergistic regulation process based on the participation of multiple genes.This study provides a theoretical basis for in-depth understanding of the antifungal activity and mechanism of AEO and AREO against Fusarium,and provides basic research support for the development of anti-Fusarium disease bio-pesticides and other antifungal agents using artemisinin extracted wastes as raw materials.AREO has a good application prospect and is expected to be developed as a green biocontrol agent for the control of plant pathogenic Fusarium disease.