Research On The Fungicide Resistance Of The Wheat Scab Fungus Fusarium Graminearum

Fusarium head blight (FHB) of wheat caused by Fusarium spp. is a devastating disease of cereal crops worldwide. The application of fungicides has been one of the primary approaches for controlling FHB. In this study, a total of 9305 Fusarium spp. isolates were collected from Jiangsu and Anhui provinces during 2014 to 2015. Fungicide sensitivity assays showed that the frequencies of carbendazim-resistant (Car-R) strains from Jiangsu province accounted for 31.2% and 37% respectively in 2014 and 2015. During 2014-2015, the resistance frequency in Anhui province went up from 5.57% to 10.26%. The tebuconazle or JS399-19 resistant isolates were not detected in the collections. The results indicated that the carbendazim should not be further used in Jiangsu province.JS399-19 is a new type of fungicide. It has become one of the main fungicides in controlling wheat head blight. In addition to inhibiting the growth of pathogen, this fungicide also reduces the production of deoxynivalenol (DON) mycotoxin. Previous studies have showed that FgMyosin I was the target of JS399-19 and the point mutations in this protein are responsible for the resistance of F. graminearum to JS399-19. In this study, we further obtained 71 JS399-19-resistant mutants by UV irradiation. Analysis of sequences of FgMyosin I from these resistant mutants indicates that the point mutations at 217,418,420,423 codons are associated with the resistance to JS399-19. Based on the point mutation, a pair of primers was designed to rapidly detect the mutation S217L rapidly. In addition, we found a transcription factor FgTF-JS which is involved in the sensitivity of F. graminearum to JS399-19, and the deletion mutant of Δ FgTF-JS showed reduced pathogenicity and DON production remarkably. Those results lay a foundation for risk assessment and resistance management for JS399-19.