| Summary: | This study mainly evaluated the broad-spectrum fungicidal activity of ε-poly L lysine (ε-PL) against 12 pathogenic fungi. We further demonstrated synergistic antifungal activity of ε-PL combined with wuyiencin against <i>Botryris cinerea</i>. The combined bio-fungicide achieved an inhibition rate of 100% for mycelial growth using ε-PL at 500 μg/mL + wuyiencin at 50 μg/mL and for spore germination using ε-PL at 200 μg/mL + wuyiencin at 80 μg/mL in vitro. This synergistic spore and mycelia-damaging effect of the combination was confirmed using scanning electron microscopy. In vivo assays with combined bio-fungicide (1500 μg/mL ε-PL + 60 μg/mL wuyiencin) on detached leaves showed depressed growth and development of the spores of <i>B. cinerea</i>. The synergistic effect was further tested in combinations of ε-PL with wuyiencin by measuring the fractional inhibition concentration index (FICI) value below 0.5. Moreover, ε-PL and wuyiencin inoculation before <i>B. cinerea</i> infection significantly increased the superoxide dismutase, peroxidase, catalase, and phenylalanine ammonia-lyase activities, which suggested their involvement in tomato defense responses to disease to minimize damage to <i>B. cinerea.</i> These findings revealed that a combined bio-fungicide comprising ε-PL and wuyiencin had a good prospect for controlling plant fungal disease.
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