Aboveground parts of mizuna plants were sprayed with 100 μg/ml L-methionine solution 3 or 10 days before inoculation. These plants were replanted in soil including Fusarium oxysporum f. sp. conglutinans (FOC). Disease severity scored at 14 days post-inoculation (dpi) was lower on L-methionine-treated plants than on untreated plants. No effect of L-methionine on mycelial growth of FOC was visible microscopically. Quantitative RT-PCR analyses of marker genes for plant defense responses (BrPR1, BrBGL2, BrLOX2, BrVSP2) in root tissues at 2 dpi showed that expression of these genes was higher in treated plants than in control plants.