2-Phenylethyl Isothiocyanate Exerts Antifungal Activity against Alternaria alternata by Affecting Membrane Integrity and Mycotoxin Production

Abstract

Black spot caused by Alternaria alternata is one of the important diseases of pear fruit during storage. Isothiocyanates are known as being strong antifungal compounds in vitro against different fungi. The aim of this study was to assess the antifungal effects of the volatile compound 2-phenylethyl isothiocyanate (2-PEITC) against A. alternata in vitro and in pear fruit, and to explore the underlying inhibitory mechanisms. The in vitro results showed that 2-PEITC significantly inhibited spore germination and mycelial growth of A. alternata—the inhibitory effects showed a dose-dependent pattern and the minimum inhibitory concentration (MIC) was 1.22 mM. The development of black spot rot on the pear fruit inoculated with A. alternata was also significantly decreased by 2-PEITC fumigation. At 1.22 mM concentration, the lesion diameter was only 39% of that in the control fruit at 7 days after inoculation. Further results of the leakage of electrolyte, increase of intracellular OD260, and propidium iodide (PI) staining proved that 2-PEITC broke cell membrane permeability of A. alternata. Moreover, 2-PEITC treatment significantly decreased alternariol (AOH), alternariolmonomethyl ether (AME), altenuene (ALT), and tentoxin (TEN) contents of A. alternata. Taken together, these data suggest that the mechanisms underlying the antifungal effect of 2-PEITC against A. alternata might be via reduction in toxin content and breakdown of cell membrane integrity.

Effects of Glucosinolate-Derived Isothiocyanates on Fungi: A Comprehensive Review on Direct Effects, Mechanisms, Structure-Activity Relationship Data and Possible Agricultural Applications

“…The compound was also shown to increase vacuolar pH, and higher vacuolar pH resulted in higher tolerance towards the compound [ 127 ]. The less polar phenethyl ITC was shown to cause a cell membrane disruption in Alternaria alternata [ 94 ]. The same was observed in case of Alternaria alternata treated with benzyl ITC [ 89 ].…”

“…Several studies were published that presented the successful inhibition of post-harvest quality loss of fruits. Again, the most widely used agent is vapor phase allyl ITC, however, some also used natural ITC mixtures with phenethyl ITC and phenyl ITC being the principal components [ 79 ], benzyl ITC [ 90 , 232 ] or phenethyl ITC [ 94 ]. Successful attempts to increase shelf-life were reported in pears [ 94 , 233 ], raspberries ( Rubus idaeus ) [ 234 ], bell peppers [ 79 ], melon [ 232 ], tomato fruits [ 90 , 235 , 236 ], strawberries [ 69 , 237 ].…”

“…Again, the most widely used agent is vapor phase allyl ITC, however, some also used natural ITC mixtures with phenethyl ITC and phenyl ITC being the principal components [ 79 ], benzyl ITC [ 90 , 232 ] or phenethyl ITC [ 94 ]. Successful attempts to increase shelf-life were reported in pears [ 94 , 233 ], raspberries ( Rubus idaeus ) [ 234 ], bell peppers [ 79 ], melon [ 232 ], tomato fruits [ 90 , 235 , 236 ], strawberries [ 69 , 237 ]. The inhibition of Penicillium expansum [ 233 ], rot-causing Alternaria alternata [ 79 , 90 , 94 , 232 ], Botrytis cinerea [ 69 , 237 ], Geotrichum candidum and Fusarium oxysporum [ 235 ] was reported.…”

AaPKAc Regulates Differentiation of Infection Structures Induced by Physicochemical Signals From Pear Fruit Cuticular Wax, Secondary Metabolism, and Pathogenicity of Alternaria alternata

“…Gradient elution conditions were after 70% retention for 1 min; gradient elution conditions are shown in Supplementary Table 2. The mass spectrometric parameters such as monitoring ion, cone voltage, and collision voltage of four Alternaria species are shown in Supplementary Table 3 (Zhang et al, 2020).…”

Sustainable Use of Bioactive Compounds from Solanum Tuberosum and Brassicaceae Wastes and by-Products for Crop Protection—A Review

“…Recent experimental evidence showed that ITCs were also promising for treatments against black spot, one of the most important diseases of pear fruit during storage caused by Alternaria alternata . The development of black spot rot on the pear fruit inoculated with A. alternata was significantly decreased by 2-PEITC fumigation [ 133 ]. The authors proposed that the antifungal effect of 2-PEITC against A. alternata might be mediated by a reduction in toxin content and breakdown of cell membrane integrity.…”