Identification And Antifungal Activity Analysis Of Volatile Compounds Produced By Endophytic Fungi HND5

An endophytic fungusstrainHND5 was isolated from healthy leaves of Brachiaria sp..According to the identification result, this fungusbelongs to a new specieofAcremonium sp.HND5 could emitvolatile organic compounds (VOCs)to inhibit a variety of tropical crops pathogenic fungi and have good control effect on potted plants.In this reserch, the VOCs from HND5 were identifiedby solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). Antifungal activity of four different kinds of VOCswas analysed. the results were as follows:The VOCs produced by HND5 were extractedwiththree kinds of different SPME fibers respectively, and 34 kinds of volatile substances were identified using GC-MS.These volatile substances included olefin, alkane, naphthalene derivatives,aromatic compounds, ketones, alcohols, halogen acids, piperidines, pyridines and amino propyl amines.With 4 kinds of different commercial pure VOCs ie 1-decene,caryophyllene,benzene,4-ethenyl-1,2-dimethoxy- and 2-methoxy-4-vinylphenol, the antifungal activity againstFusarium oxysporum, Colletotrichum gloeosporioides,Corynespora cassiicola were analyzed respectively. Within these compounds, caryophyllene,benzene,4-ethenyl-1,2-dimethoxy- and 2-methoxy-4-vinylphenol were found antagonistic against growth of F. oxysporum, C. gloeosporioides and C. cassiicola. The EC50 values of caryophyllene to hypha growth of F.oxysporum, C. gloeosporioides and C. cassiicola were 2916.11μL/L, 729.56μL/L and 27.56μL/L, respectively. The EC50 values of Benzene,4-ethenyl-1,2-dimethoxy- to hypha growth of F. oxysporum, C. gloeosporioides and C.cassiicola are 62.67μL/L, 27.56μL/L and 21.22μL/L, respectively. and the EC50 values of 2-methoxy-4-vinylphenol to hypha growth of F.oxysporum, C. gloeosporioides and C.cassiicola are 36.75μL/L, 34.56μL/L and 62.58μL/L, respectively. We also found that three kinds of VOCs could inhibit the spore germination of C.gloeosporioides and F. oxysporum,and the inhibition effect enhanced by processing time.All the VOCs-treated pathogens were checked with optical microscope after treated by trypan blue. The results showed thatthe hyphae treated with VOCs were blue, but the control was not dyed. By using the transmission electron microscopy (TEM) to check Foc4 hyphae after VOCs treatment, it was found that the cell contents of hyphae leaked with deformity and constriction.The mechanism of VOCs may associate with the damage of pathogenic cell membranes.Aftertreatment by three kinds of volatile substances, the C. gloeosporioides and C.cassiicola were inoculatedonfresh rubber leaves. the virulence was lower or loss in different degrees compared with wild type strains treated by 2-methoxy-4-vinylphenol and benzene,4-ethenyl-1, 2-dimethoxy-,and the caryophyllene had no effect.After the treatment, thespores content of F. oxysporumin the soil were reduced with different degree by 2-methoxy-4-vinylphenol and benzene,4-ethenyl-1,2-dimethoxy- treatment, and the caryophyllene also had no effect.