Abstract: The inhibitory effects of trans-2-hexenal, a plant-derived volatile substance, on the growth of Alternaria alternata and black spot development in pear fruit inoculated with this fungal pathogen were studied, and its underlying mechanism was also evaluated by examining cell membrane integrity. Results showed that trans-2-hexenal significantly inhibited the spore germination and mycelium growth of A. alternata in a concentration-dependent manner. The spore germination rate and colony diameter of A. alternata after treatment with 2.0 μL/mL were only 13.9% and 36.67% when compared with the control. At the same time, trans-2-hexenal fumigation treatment effectively reduced the development of pear black spot. Further research showed that the trans-2-hexenal treatment severely destroyed A. alternata cell integrity and significantly increased membrane conductivity and nucleic acid leakage rate (P < 0.05). Additionally, trans-2-hexenal treatment reduced the production of four mycotoxins in A. alternate including monomethyl ether, alternariol, altenuene and tentoxin to different extents. These findings suggested that the trans-2-hexenal might effectively reduce the growth and pathogenicity of A. alternata through damaging cell membrane integrity and decreasing mycotoxin production.

Key words: pear black spot, Alternaria alternata, trans-2-hexenal, antifungal activity, cell membrane, mycotoxin