The Screening Of Marine Fungi Against Tea Gray Blight Disease And The Isolation And Analysis Of Fungal Secondary Metabolites With Antifungal Activity

There are abundant fungal resources in the mangroves,which are also a rich source of natural products,where the natural products have novel structure types and a variety of biological activities.Therefore,both mangrove fungi resources and natural products derived from mangrove fungi have the potential to develop new agricultural active compounds.In order to analyze the diversity of mangrove-derived fungi,mangrove-derived fungal isolates were obtained from sediment samples from the Zhangjiangkou Mangrove Nature Reserve in Fujian Province through the experiment about strain isolation,and the fungi derived from mangrove sediment were further used for screening experiments against the gray blight disease caused by Pestalotiopsis theae LH13,to obtain antifungal isolates and extract of secondary metabolites by fungal fermentation and ethyl acetate extraction.Compounds are separated from antifungal extract of secondary metabolites,were subjected to screening experiments to obtain agricultural compounds with antifungal activity and the chemical composition of compounds were analyzed.This subject research provides technical support for new pesticide products,and contributes to the protection of the national ecological environment safety and the quality and safety of agricultural products,as well as the promotion of the sustainable and healthy development of the agricultural economy.There were 103 fungi strains isolated from mangrove sediment samples by the spread plate method and the streak plate.The fungal mycelium,ester-phase secondary metabolites and compounds were tested against the pathogenic fungus Pestalotiopsis theae LH13 of gray blight disease by the slab face-off method.The chemical composition of the fungus Fusarium solani H915 were analyzed by the methods of silica gel column chromatography,reversed-phases ODS column chromatography,thin-layer chromatography and high performance liquid chromatography combined with 1D/2D-NMR and MS.The diversity of fungi derived from mangrove sediment samples were analyzed,the result showed that these three species,namely Aspergillus,Penicillium and Trichoderma,are the most important part in fungal species derived from mangrove sediment.The number of these three species is the largest part of the total number of fungi derived from mangrove sediment.According the result of antifungal activity about fungal mycelium and extract,the isolate Fusarium solani H915 was selected for other experiments due to its obvious antifungal activity with70% inhibition.For Fusarium solani H915,12 compounds have been isolated and purified,namely Fusarilactone A(1),Fusarilactone B(2),Fusarilactone C(3),Fusaridioic acids B(4),Fusaridioic acids C(5),(2E,4E,7S)-12,14-dihydroxy-3,5,7-trimethyl-tetradeca-2,4-dienoicacid(6),Hymeglusin(7),(2E,4E,7S,8E,12 S,13S)-12-hydroxy-13-(hydroxy-methyl)-3,5,7-trime-thyltetradeca-2,4,8-trienedioic acid(8),(2E,5E)-3,5,7-trimethylocta-2,5-dienedioicacid(9),(2E,4E)-3,5,7-trimethylocta-2,4-dienedioic acid(10),L-660282(11)and Fusaridioic acid A(12).The 12 compounds were screened for antifungal activity against the pathogenic fungus Pestalotiopsis theae LH13 of tea gray blight disease,and the results showed that the Fusarilactone A(1),Fusarilactone B(2)and Hymeglusin(7)have antifungal activity.In conclusion,the dominant species of mangrove-derived fungi are Aspergillus,Penicillium and Trichoderma,and there are more antifungal strains belong to Trichoderma.Among 103 fungal isolates derived from mangrove sediment samples,the fungus Fusarium solani H915 with antifungal activity against pathogenic fungus of tea gray blight disease was selected,and the Fusarilactone A(1),Fusarilactone B(2)and Hymeglusin(7)isolated from Fusarium solani H915 have antifungal activity.This experimental results provide R&D resources and technical support for new pesticide products.