Inhibitory Effect of Linalool against the Ginger Fusarium Wilt Pathogen

Abstract

To study the antifungal effect and mechanism of linalool against Fusarium oxysporum FOX-1, the causative agent of ginger Fusarium wilt, the damaging effects of different concentrations of linalool on the mycelial growth, spore germination and cell membrane of F. oxysporum FOX-1, and its control effect on ginger Fusarium wilt were systemically investigated. The results showed that linalool could significantly inhibit the mycelial growth of F. oxysporum FOX-1 in a concentration-dependent manner, and the half maximal effective concentration (EC50) and the minimum inhibitory concentration (MICs) were 1.183 and 2 g/L, respectively. The spore concentration of F. oxysporum FOX-1 treated with linalool at MIC for 6 h was (1.43 ± 0.12) × 104 spores/mL, which was significantly lower than that of the control group ((5.79 ± 0.19) × 104 spores/mL) (P < 0.05), and the spore germination rate of F. oxysporum FOX-1 treated with linalool at MIC for 12 h was (5.83 ± 2.16)%, which was significantly lower than that of the control group ((95.12 ± 3.78)%) (P < 0.05). Treatment with linalool at 1/2 MIC and MIC damaged the integrity of the cell membrane, resulting in a significant increase in relative electrical conductivity and nucleic acid leakage in the mycelial suspension and malondialdehyde (MDA) content in the mycelium, and a significant decrease in ergosterol content, finally weakening the pathogenicity of the fungus. No lesions appeared on ginger pieces after treatment with linalool at MIC for 3 days. In conclusion, linalool affects the normal physiological function of F. oxysporum FOX-1 by inhibiting its spore germination and mycelial growth and destroying its cellular structure. This study provides a new direction for the effective control of Fusarium wilt.

Keywords

• linalool; fusarium oxysporum; antifungal activity; membrane permeability