Phenamacril disrupted toxisome formation and subsequently inhibited DON production.

(A) Tri1-GFP localized to the spherical structures (termed as toxisomes) in hyphae grown in TBI but not in PDB or MM. Images were taken after each strain was incubated at 28 °C for 48 h. Bar = 10 μm. DIC indicates differential interference contrast. (B) After growth in TBI for 48 h, hyphae of ΔTri1::Tri1-GFP were stained with the ER-tracker red and examined for GFP and ER tracker signals. Bar = 10 μm. (C) After growth in TBI for 48 h, hyphae of PH-1::Tri1-GFP+H1-RFP were examined for the co-localization of H1-RFP and Tri1-GFP. Bar = 10 μm. (D) Hyphae of ΔTri1::Tri1-GFP were treated with 0.5 μg/ml phenamacril, or 1.4 μg/ml carbendazim for 24 h in TBI before examination for GFP signals. The solvent DMSO was used as a control. Bar = 10 μm. (E) Western blots of proteins isolated from the same set of samples used in 1D were detected with the anti-GFP or anti-GAPDH antibody. (F) DON production was assayed for the wild-type PH-1 growth in TBI supplemented with 0.5 μg/ml phenamacril or 1.4 μg/ml carbendazim. The solvent DMSO was used as a control. Values on the bars followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at P = 0.05. (G) Phenamacril inhibited toxisome formation in hyphae of ΔTri1::Tri1-GFP inoculated on wheat leaf. (H) Efficiencies of phenamacril (375 g/ha) and carbendazim (750 g/ha) in controlling Fusarium head blight (FHB) and DON contamination in the field trials. Values on the bars for disease incidence or DON production followed by the same letter are not significantly different according to a Fisher’s least significant difference (LSD) test at P = 0.05.