Enantiomers Of Tebuconazole And Hexaconazole Affect DON Produced By Fusarium Graminearum

Fusarium graminearum is one of the major pathogens causing FHB.Not only does it infect wheat to reduce its yield,it also produces mycotoxins that affect the quality of wheat and health of consumer.Tebuconazole and hexaconazole are common agents for controlling fungal diseases such as FHB.They each have two enantiomers,which are usually used as a fungicides in the form of racemates.The bioactivity of the enantiomers against the target pathogens is not the same,and there are usually large differences.However,their effect on mycotoxin production by fungi is not currently reported.In this study,F.graminearum was used as a test strain to investigate the fungicide activity of tebuconazole,hexaconazole and their enantiomers,and the effect of these enantiomers on DON accumulation by this strain.The contents is as follows:1.The biological activities of tebuconazole and hexaconazole and their enantiomers against F.graminearum under different conditions of water activity(0.997,0.975 and 0.950)and temperature(20 ?,25 ? and 30 ?).(1)The biological activities of tebuconazole and hexaconazole on F.graminearum were(-)-tebuconazole> tebuconazole racemate>(+)-tebuconazole;(-)-hexaconazole > hexaconazole racemate>(+)-hexaconazole.(2)The culture temperature,water activity,type of compounds and their interactions significantly affected(p < 0.05)the biological activity of the compounds against the strain.2.After the enantiomerics treatment of doses of EC10,EC50 and EC90,F.graminearum produced DON at different water activities and temperatures.(1)The dose,culture temperature,and water activity all significantly affected the amount of DON produced by F.graminearum(p < 0.05).(2)The amount of DON produced by F.graminearum was higher than that of(+)-tebuconazole-treated samples after treatment with tebuconazole and(-)-tebuconazole;the enantiomerics composition of hexaconazole was different effects on the amount of DON produced at different temperatures and water activities.(3)Low doses of tebuconazole and hexaconazole and enantiomers may cause F.graminearum to produce more DON.High doses of hexaconazole and tebuconazole and enantiomers effectively reduce DON produced by F.graminearum.3.The expression of Tri5 and Tri6 genes related to DON synthesis of F.graminearum in different concentrations of tebuconazole and hexaconazole.(1)After treatment with high concentrations of(+)-tebuconazole,the expression of Tri5 and Tri6 genes was higher than that of(-)-tebuconazole and tebuconazole racemates.(2)The low and medium concentrations of hexaconazole and tebuconazole and enantiomers stimulate the expression of Tri5 and Tri6 genes.The expression of Tri5 and Tri6 genes was inhibited under the high concentrations of hexaconazole,(-)-tebuconazole and tebuconazole racemization.