Bacteria Associated with Winter Wheat Degrade <i>Fusarium</i> Mycotoxins and Triazole Fungicide Residues

Abstract

Fusarium head blight (FHB) is the most dangerous spike disease of wheat, and triazole fungicides are generally recommended for FHB control. Bacteria isolates obtained from wheat grain were identified as members of the genus Sphingomonas based on 16S rDNA gene sequence analysis. The degradation of propiconazole and trichothecenes was analyzed by high-performance liquid chromatography. Two field experiments were conducted to determine the effectiveness of the biological treatment. All of the tested Sphingomonas isolates produced surfactin. Moreover, all strains were effective in degrading propiconazole and exhibited inhibitory effects on pathogens that cause FHB in wheat. Sphingomonas isolate S11 was selected for the field experiment because it inhibited the development of F. culmorum colonies in vitro by 48.80%, and degraded propiconazole in 15.13% after 48 h. The application of Sphingomonas S11 suspension during the growing season of winter wheat decreased the deoxynivalenol (DON) content of grain inoculated with F. culmorum more than 22-fold. Sphingomonas sp. strain S11 applied after fungicides also decreased the contamination of grain with fungi of the genus Fusarium and their mycotoxins. The analyzed bacteria can be potentially used to protect wheat against FHB pathogens, increase yields and improve grain quality by eliminating dangerous mycotoxins and propiconazole residues.

Keywords

• propiconazole
• <i>Sphingomonas</i>
• fusarium head blight
• surfactin
• trichothecenes
• deoxynivalenol