Inactivation of tobacco mosaic virus using gamma irradiation and its potential modes of action.

Gamma irradiation is a non-thermal processing technique used to disinfect harmful microorganisms in agriculture. This technology has been shown to be an effective method to control bacterial and fungal plant pathogens. However, its effect on viral plant pathogen is less understood. Gamma irradiation was evaluated for the inactivation of tobacco mosaic virus (TMV). TMV infectivity has gradually decreased following irradiation in a dose-dependent manner and virus was completely inactivated at a dose over 40 kGy. Transmission electron microscopy revealed that increased gamma irradiation disrupts the virion structure and degrades viral proteins, which results in TMV inactivation. The mechanisms, through which gamma irradiation inactivates TMV, can be directly associated with the damage to the virus constituents.

Antifungal effect of gamma irradiation and sodium dichloroisocyanurate against Penicillium expansum on pears.

UNLABELLED: Gamma irradiation (GI) was evaluated for its in vitro and in vivo antifungal activity against Penicillium expansum on pear fruits. GI showed a complete inhibition of spore germination, germ tube elongation and mycelial of P. expansum, especially 1·8 kGy. GI affected the membrane integrity and cellular leakage of conidia in a dose-dependent manner. Furthermore, the leakage of protein and sugar from mycelia increased along with the dose. GI was evaluated at lower doses in combination with a chlorine donor, sodium dichloro-s-triazinetrione (NaDCC), to examine the inhibition of P. expansum. Interestingly, only a combined treatment with 0·2 kGy of GI and 70 ppm of NaDCC exhibited significant synergistic antifungal activity. The mechanisms by which the combined treatment decreased the blue mould decay of pear fruits could directly associated with the disruption of the cell membrane of the fungal pathogen, resulting in a loss of cytoplasmic materials from the hyphae. SIGNIFICANCE AND IMPACT OF THE STUDY: Gamma irradiation (GI) is used as an effective nonchemical approach to inactive pathogens. This study investigated the antifungal effect of gamma irradiation and its combined treatment with a chlorine donor on this fungal pathogen, both in vitro and in vivo. This study emphasized that the integration of low-dose GI and a chlorine donor, NaDCC, exhibited a significant antifungal effect, and that its mechanisms are directly associated with membrane integrity of fungal spores, promising that GI has the potential to be an antifungal approach.