Functional Study Of Mannosyltransferase Complex In Fusarium Graminearum

Wheat head blight caused by Fusarium graminearum is one of the important fungal diseases of wheat.Wheat blast causes grain yield reduction or even crop failure,and its production of Deoxynivalenol（DON）and Nivalenol（NIV）can affect human and animal health after consumption.In Saccharomyces cerevisiae and Candida albicans,deletion of the mannosyltransferase complex results in various degrees of defective phenotypes,including impaired cytoskeleton initiation or lengthening,slowed growth,cell cycle arrest,fragile cell wall structure,and increased susceptibility to fungicides and osmotic stress.increased susceptibility to fungicides and osmotic stress.However,the functions of the mannosyltransferase complex component proteins Van1,Mnn9,and Anp1 in phytopathogenic fungi are not known.In this study,we report the basic biological functions of F.graminearum FgVan1,FgMnn9 and FgAnp1.The knockout mutantsΔFgMnn9,ΔFgAnp1 andΔFgVan1 were obtained based on the principle of homologous recombination and gene complementation techniques;the backcomplementΔFgMnn9-C,ΔFgAnp1-C andΔFgVan1-C.A series of biologically based phenotypic experiments were conducted to analyze the deletion of FgVan1,FgMnn9 and FgAnp1,which resulted in nutrient growth.The deletion of FgVan1,FgMnn9 and FgAnp1 resulted in hindered nutritional growth and increased mycelial terminal branching,especially inΔFgAnp1.ΔFgMnn9,ΔFgAnp1 andΔFgVan1 conidial production decreased by 62.5%,12%and 30%,respectively,relative to the wild type,and the septum ofΔFgAnp1 decreased,but the black light-induced ascospores increased to different degrees relative to the wild type.In the external stress factor sensitivity test,ΔFgVan1 became less sensitive to Na⁺or K⁺stress;less sensitive to metal cations Ca²⁺and Mg²⁺;and more tolerant to H₂O₂ but more sensitive to Caffeine.In contrast,the deletion of FgAnp1 showed less similar traits.ΔFgAnp1 was less sensitive to 0.25μg/m L Tebuconazole,0.5μg/m L Carbendazim,0.25μg/m L Cyhalothrin,0.5μg/m L Acetamiprid,0.5μg/m L Clofentezine,0.2 mg/m L Congo Red,0.02%SDS,1 M KCl,1 M Na Cl,15 m M H₂O₂ and 4 m M Cu SO₄·5H₂O,all 11 stress factors were tolerated to different degrees,especially K⁺,Na⁺and Cu²⁺.The results indicate that FgVan1 and FgAnp1 have the ability to regulate osmotic stress,metal ion tolerance,oxidants and cell wall permeability andΔFgAnp1 is more resistant to fungicides.Field pathogenicity tests revealed that the deletion of FgVan1,FgAnp1 and FgMnn9 inhibited the spread of mycelium on wheat,resulting in a decrease in its infectivity.The localization of TRI1 protein and the DON toxin assay clearly demonstrated that the deletion of FgVan1,FgMnn9 and FgAnp1 in F.graminearum resulted in impaired DON toxin biosynthesis.In summary,the results of this study suggest that FgVan1,FgMnn9 and FgAnp1 play an integral role in the growth and development of F.graminearum,pathogenic virulence production and stress to external stresses.