Abstract:
To clarify the inhibitory effect and molecular mechanism of eugenol on
Fusarium oxysporum (the pathogen of tobacco fusarium root rot disease), the inhibition rate of eugenol on mycelial growth of
F.
oxysporum was determined by the mycelial growth rate method. The inhibition rate of eugenol on spore germination of
F.
oxysporum was determined by the spore germination test. The effect of eugenol on the membrane integrity of
F.
oxysporum was analyzed by propidium iodide staining, conductivity and extracellular protein content determination. The molecular mechanism of eugenol inhibition of
F.
oxysporum was analyzed by transcriptome sequencing. The results showed that the inhibition rates of eugenol on the mycelial growth of
F.
oxysporum were 42.41%, 53.96%, 92.47% and 99.82%, respectively, after 72 h of culture on PDA medium with eugenol concentrations of 62.5, 125.0, 250.0 and 500.0 μg/mL. When eugenol was added to the spore suspension of
F.
oxysporum at concentrations of 62.5, 125.0, 250.0 and 500.0 μg/mL, the inhibition rates of eugenol on spore germination of
F.
oxysporum were 16.80%, 24.34%, 58.98% and 81.50%, respectively. According to propidium iodide staining, the membrane integrity of
F.
oxysporum treated with eugenol (250 μg/mL) was damaged. After treatment with eugenol (250 μg/mL) for 12 h, the extracellular conductivity of
F.
oxysporum increased from 0.89 to 1.26 mS/cm. After treatment with eugenol (250 μg/mL) for 8 h, the soluble protein content increased from 0.236 7 to 0.911 5 mg/mL. Transcriptome sequencing analysis showed that there were 2 548 genes with significant differences between eugenol (250 μg/mL) treated and control 3 treatment. Among them, 1 395 genes were up-regulated and 1 153 genes were down-regulated. GO functional classification analysis showed that the differentially expressed genes were mainly enriched in signal transduction, proteasome complex and nucleotide binding components. KEGG functional enrichment showed that the differentially expressed genes were mainly enriched in endocytosis, oxidative phosphorylation and purine metabolism.
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