title: Inhibitory effect of gamma irradiation and its application for control of postharvest green mold decay of Satsuma mandarins.
abstract: Gamma irradiation has been shown to be effective for the control of postharvest fungi in vitro, but little is known regarding antifungal action, responses to gamma irradiation, and its application to fresh produce. Gamma irradiation was evaluated for its in vitro and in vivo antifungal activity against Penicillium digitatum on Satsuma mandarin fruits. Green mold was inhibited in a dose-dependent manner. Gamma irradiation showed a complete inhibition of spore germination, germ tube elongation, and mycelial growth of P. digitatum, particularly at 1.0kGy. To further investigate the mechanisms by which gamma irradiation inhibits fungal growth, the membrane integrity and cellular leakage of conidia were tested, indicating that gamma irradiation results in the loss of plasma membrane integrity, causing the release of intracellular contents such as soluble proteins. In vivo assays demonstrated that established doses can completely inhibit the growth of fungal pathogens, but such high doses cause severe fruit damage. Thus, to eliminate the negative impact on fruit quality, gamma irradiation at lower doses was evaluated for inhibition of P. digitatum, in combination with a chlorine donor, sodium dichloro-s-triazinetrione (NaDCC). Interestingly, only a combined treatment with 0.4kGy of gamma irradiation and 10ppm of NaDCC exhibited significant synergistic antifungal activity against green mold decay. The mechanisms by which the combined treatment decreased the green mold decay of mandarin fruits can be directly associated with the disruption of cell membrane of the fungal pathogen, which resulted in a loss of cytoplasmic material from the hyphae. These findings suggest that a synergistic effect of combining treatment with gamma irradiation with NaDCC has potential as an antifungal approach to reduce the severity of green mold in mandarin fruits.
authors.affiliation: Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea. Electronic address: jraed2@kaeri.re.kr.
authors.forename: Rae-Dong
authors.initials: RD
authors.lastname: Jeong
authors.affiliation: Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea.
authors.forename: Eun-Hee
authors.initials: EH
authors.lastname: Chu
authors.affiliation: Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea.
authors.forename: Gun Woong
authors.initials: GW
authors.lastname: Lee
authors.affiliation: Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea.
authors.forename: Chuloh
authors.initials: C
authors.lastname: Cho
authors.affiliation: Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea.
authors.forename: Hae-Jun
authors.initials: HJ
authors.lastname: Park
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000528:radiation effects*; D002957:Citrus / Q000382:microbiology* / Q000528:radiation effects; D005638:Fruit / Q000382:microbiology*; D005720:Gamma Rays / Q000009:adverse effects; D025301:Hyphae / Q000528:radiation effects*; D008855:Microscopy, Electron, Scanning; D010407:Penicillium / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D013172:Spores, Fungal / Q000528:radiation effects* / Q000648:ultrastructure; D014227:Triazines / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D014227:Triazines; C011765:troclosene
keywords: Cellular leakage; Gamma irradiation; Membrane integrity; NaDCC; Penicillium digitatum