Monitoring Of Fungicide Resistance And Mode Action Of Natural Active Compound FM-A Against Fusarium Graminearum

Fusarium head blight（FHB）caused by Fusarium graminearum species complex is a devastating disease of cereal crops worldwide.In addition to the yield loss caused by the disease,mycotoxins deoxynivalenol（DON）and its derivatives,produced by the pathogens in infested grains,represent a serious threat to human and animal health.Thus,FHB has been listed as one of the first class crop pests in China.Currently,management of FHB is mainly dependent upon fungicide application.However,the pathogens have developed resistance to some fungicides after a long history of fungicide application.In this study,we monitored the resistance of F.graminearum to several fungicides in 14839 F.graminearum strains collected from Jiangsu、Anhui and Henan provinces during 2018-2020,and found that the average proportion of carbendazim resistant strains was 38.07%in Jiangsu,12.50%in Anhui and 4.95%in Henan.Additionally,tebuconazole low resistant strains have been detected with a proportion of 12.34%in Henan province in 2020,but not detected in Jiangsu and Anhui Province.The resistant strains to phenamacril and prochloraz have not been detected yet in the tested samples.These results are important for chemical control of FHB in China.Since the efficacy of traditional control methods remains highly variable,biological control is receiving growing interest using living microorganisms or their derivatives to reduce a targeted pathogen.In a previous study,we isolated a biocontrol fungus,named as FM324.In current study,we found that secondary metabolites of FM324 could efficiently inhibit hyphal growth and toxin production of F.graminearum.The genome sequencing assay showed that FM324 is a straon of Aspergillus felis.An active compound FM-A,unsaturated fatty acid derivatives,was isolated from this strain by ethyl acetate extraction,concentration and HPLC assays.The chemical structure of the compound was identified as C₂₉H₅₀N₄O₅ by spectrum analysis.SCI-Finder assay showed that FM-A is a novel compound.Phenotypic assays showed that FM-A could deform mycelial morphology and inhibit DON production of F.graminearum.Additionally,Lae A could up-regulate the production of FM-A in FM324.Taken together,these results provide useful information for development of FM324 for management of FHB.