Study on the Antifungal Activity of Gallic Acid and Its Azole Derivatives against Fusarium graminearum

The wheat scab caused byFusarium graminearum(F. graminearum) has seriously affected the yield and quality of wheat in China. In this study, gallic acid (GA), a natural polyphenol, was used to synthesize three azole-modified gallic acid derivatives (AGAs1–3). The antifungal activity of GA and its derivatives againstF. graminearumwas studied through mycelial growth rate experiments and field efficacy experiments. The results of the mycelial growth rate test showed that the EC50of AGAs–2 was 0.49 mg/mL, and that of AGAs–3 was 0.42 mg/mL. The biological activity of AGAs–3 onF. graminearumis significantly better than that of GA. The results of field efficacy tests showed that AGAs–2 and AGAs–3 significantly reduced the incidence rate and disease index of wheat scab, and the control effect reached 68.86% and 72.11%, respectively. In addition, preliminary investigation was performed on the possible interaction between AGAs–3 andF. graminearumusing density functional theory (DFT). These results indicate that compound AGAs–3, because of its characteristic of imidazolium salts, has potential for use as a green and environmentally friendly plant-derived antifungal agent for plant pathogenic fungi.