A Study On Anti-Phytopathogenic Activities Of Endophytic Fungi From Artemisia Annua

Endophytic fungi are great microbial resources in respects of industry,agricultural production and significant health science.Antibacterial endophytes have become a research hotspot,from which people can discover a lot of new active compounds.They can be used in medicinal research and disease control on agricultural plant.Artemisia annua L.is a traditional Chinese medicine,which is widely used in treating various diseases.Fungal endophyte isolates from this medicinal plant have antimicrobial,antitumor and antioxidant activity.This study explored 34 strains of endophytes from A.annua against Botryosphaeria dothidea B12,Collectotrichum sp.B6,Monilinia laxa LHF,Phoma sp.HGHM and Alternaria alternate RSF respectively,Flat-stand memthold were used.Results showed that the strain WC-QHY-02-03 has a better antifungal activity and wide antimicrobial spectrum.The inhibition rates against phoma sp.(soft rot of Kiwifruit)and several pathogenic fungi in Kiwifruit were 81.16% and over 50% respectively.The studies on the strain WC-QHY-02-03 showed that the best growing condition for the strain are 24-32 ℃,6.0 of initial p H value,glucose as carbon source,beef extract as nitrogen source.According to morphological and molecular phylogenetic analyses,the strain was identified as Trichoderma harzianum.Optimizing experiments of fermentation condition showed that the best culture conditions were as follows: sucrose 30.0 g/L,Na NO3 12.0 g/L,Mg SO4 1.5 g/L,K2HPO4 3.0 g/L.It was the best to incubate the fungus for 12 days within 4% inoculum quantity and initial p H 7.The optimized fermentation liquor have inhibitory effect against three kinds of pathogenic fungi of Kiwifruit,The inhibition rates of fermentation liquid at concentrations of 100% against Botryoshaeria dothidea,Collectotrichum sp.and Alternaria alternate reached 80.26%,79.12%,45.84% respectively.The ethyl acetate extracts of fermentation liquid had good antifungal activity to the four kinds of fungal diseases-Colletotrichum sp.,Botryosphaeria dothidea,phoma sp.and Alternaria alternate.The crude extract was separated and purified by silica gel column chromatography,TLC and a relatively pure component A was obtained.The inhibition rates were used to measure the antagonistic effect of component A.The microscopy results showed that the component A probably cause fractured hyphae,plasma extravasation form cavity and restrained hyphae growth in phoma sp.The EC50 was 63.95 μg/m L.