Study On Antifungal Activities Of Endophytic Fungi From Hopea Chinensis And Melodinus Suaveolens

Endophytic fungi are important microbial resources with potential for the development of pesticide activities.Secondary metabolites of endophytic fungi have good antifungal activities and have important influence in the field of pesticide creation.In this study,the two endemic plants of Hopea chinenisis Hand.-Mazz.and Melodinus suaveolens Champ.ex Benth found in Guangxi were studied.Endophytic fungi from these two plants were isolated and identified by means of tissue culture and molecular biology.The bioactivity of the endophytic fungi were evaluated in order to provide potential antifungal activity in plants.Fungi development data based on the morphology and molecular biology of the fungi and the sequence similarity comparison of NCBI GenBank,20 endophytic fungi were isolated from the roots,branches and leaves of M.suaveolens,which belonging to 2 phyla,2 subphyla,5 classes,15 orders,15 families and 15 genera;13 endophytic fungi were isolated from the roots of H.chinenisis,which belonging to 2 phyla,2 subphyla,5 classes,9 orders,12 families and 13 genera.The result showed that M4 strain from M.sucaveolens and H21 strain from H,chinenisi.s had potent antifungal activity against Pyricularia grisea(Cooke)Sacc by the way of plate confr-ontation assay,and the inhibition rate reached more than 50%.For deep study which test the inhibition rate by mycelial growth rate method through calculated by measuring the diameter was found that the fermentation broth with the concentration of 20 mg/mL for M4 strain has 40.92%against F.graminearum and H12 strain has 60.23%against F.oxysporum race 4.And then,the inhibition rate by mycelial growth rate method through calculated by measuring the diameter for H12 strain was found that the crude extract for petroleum ether,ethyl acetate,acetone and methanol with the concentration of 10 mg/mL have no activity against F.oxysporum race 4 and those have potent antifungal activity against C.musae,N.dimidiatum and P.grisea.The crude extract of petroleum ether with significant inhibitory effect had 18.15%antigungal activity against P.grisea,the crude extract of ethyl acetate had 32.84%antifungal activity against C.musae.the methanol crude extract had 76.79%antifungal activity against P.grisea,and the acetone crude extract had 43.95%antifungal activity against C.musae.Combination of gene cloning and sequence analysis to construct the phylogenetic tree which identified H12 strain as piptoporellus soloniensis.By using silica gel column chromatography,gel Sephadex LH-20 column chromatography and thin layer chromatography,the chemical constituents of P.soloniensis mycelia methanol and acetone crude extract were separated and identified 3 compounds.The first compound identified was ergosta-5,7,22-trien-3β-of,the second compound was(22E)-5α,8α-epidioxyergosta-6,22-dien-3β-ol,and the third compound need to be identified.Compound 2 showed no significant antifungal activity against F.oxysporum race 4,P.grisea,C.musae and N.dimidiatum.In this study,33 endophytic fungi were isolated and identified from H.chinenisis and M.suaveolens.Among them,P.soloniensis strain had significant antifungal activity which evaluated the antifungal activity from its fermentation broth and crude mycelium extract.The results showed that both of plants had endophytic fungi which could be used as biogenic fungicides and had important development value in agriculture.