| Endophytic fungi can produce a variety of secondary metabolites,and these secondary metabolites possess good biological activities.As a source of phytoalexins,endophytic fungi have received widespread attention in recent years.In this study,three cajanol-producing endophytic fungi were isolated from pigeon pea[Cajanus cajan(L.)Millsp.]by LC-MS/MS detection.Also,the morphological and molecular identification were also studied.The fermentation conditions were optimized based on the cajanol yield,then the activity of aiti-plant pathogen was preliminarily evaluated.Conclusions were summarized below:1.Three cajanol-producing endophytic fungi were isolated from pigeon pea and systematic identified;A total of 172 strains endophytic fungi were isolated from pigeon pea roots,stems,leaves,flowers,bean-pod and seeds.According to the morphological identification,these endophytic fungi belong to Fusarium sp.,Alternaria sp.,Hypocrea sp.,Penicillium sp.,Chaetomium sp.,Aspergillus sp.,Myrothecium sp.,Colletotrichum sp.,Exserohilum sp.,Bipolar is sp.,Nigrospora sp.,Bionectria sp.,Neonectria sp.,Arthrinium sp.and Coprinellus sp.,respectively.After the LC-MS/MS detection,three endophytic fungi could produce cajanol.They were R-1 8,R-30,R-38,respectively.Furthermore,morphology and molecular identification indicated that the three endophytic fungi are most closely related to Hypocrea lixii.2.The optimum fermentation conditions of endophytic fungus R-18 were obtained by optimization of the fermented medium and the culture conditions;R-18 was selected to optimize the fermentation conditions for cajanol production effected by different single factors,such as different fermented medium,carbon source,nitrogen source,culture time,culture temperature and the initial pH value of the medium.The results showed that the optimum fermentation medium:PDB medium,2%glucose as carbon source.Culture time,culture temperature and the initial pH value of the medium were selected to central composite design and response surface optimization.The best fermentation conditions were:culture time:6 days,temperature:28℃,pH value:6.The maximum yield of cajanol from R-18 was 927.00±0.725 μg/L.3.The activity of fungal cajanol against plant pathogens was studied.Then,the biocontrol effects of fungal cajanol against soybean root rot and cucumber fusarium wilt were investigated by greenhouse experiments;Soybean root rot Fusarium oxysporum,tomato Botrytis cinerea,Phytophthora capsici,rice Sheath blight,cucumber fusarium will and Pythium aphanidermatum were selected to evaluate the activity of fungal cajanol against plant pathogens.The cajanol-producing fungal endophytes were found to have inhibited effect of soybean root rot Fusarium oxysporum and cucumber fusarium wilt.The best inhibition fungal endophyte R-18 was selected to do plant pathogen mycelial growth inhibition assay.The inhibition zone diameters were 28± 0.5 mm and 25±0.2 mm,respectively.The efficacies of fungal cajanol on soybean and cucumber seedlings were investigated.The results showed that the concentration of the extracts was 10 mg/mL,the control effects on soybean root rot and cucumber fusarium wilt were 89.76%,and 90.16%.In this study,three endophytic fungi producing cajanol were isolated from pigeon pea and identified systematic;the best fermented technology conditions of endophytic fungus R-18 with high level cajanol were obtained by optimizing the fermented medium and culture conditions;the activity of crude extracts against plant pathogens was studied.Then,the biocontrol effects of crude extracts against soybean root rot and cucumber fusarium wilt were investigated by greenhouse experiments.In summary,this study has laid a solid foundation for the effective use of pigeon pea endophytic fungi and its active ingredient cajanol,also provided a new source of microbial pesticide research and development new path and method!... |
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