Effects of epsilon-Poly-L-Lysine Combined with Wuyiencin as a Bio-Fungicide against Botryris cinerea

This study mainly evaluated the broad-spectrum fungicidal activity of epsilon-poly L lysine (epsilon-PL) against 12 pathogenic fungi. We further demonstrated synergistic antifungal activity of epsilon-PL combined with wuyiencin against Botryris cinerea. The combined bio-fungicide achieved an inhibition rate of 100% for mycelial growth using epsilon-PL at 500 mu g/mL + wuyiencin at 50 mu g/mL and for spore germination using epsilon-PL at 200 mu g/mL + wuyiencin at 80 mu g/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 mu g/mL epsilon-PL + 60 mu g/mL wuyiencin) on detached leaves showed depressed growth and development of the spores of B. cinerea. The synergistic effect was further tested in combinations of epsilon-PL with wuyiencin by measuring the fractional inhibition concentration index (FICI) value below 0.5. Moreover, epsilon-PL and wuyiencin inoculation before B. cinerea 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 B. cinerea. These findings revealed that a combined bio-fungicide comprising epsilon-PL and wuyiencin had a good prospect for controlling plant fungal disease.