College of Food Science and Technology, Nanjing Agricultural University, Nanjing, China.
J Appl Microbiol. 2018 Jan;124(1):166-178. doi: 10.1111/jam.13612. Epub 2017 Dec 18.
This study aimed to investigate the antifungal mechanism of carvacrol and eugenol to inhibit Rhizopus stolonifer and the control of postharvest soft rot decay in peaches.
To investigate the antifungal mechanism, the effects of carvacrol and eugenol on the mycelium growth, leakages of cytoplasmic contents, mycelium morphology, cell membrane and membrane composition of R. stolonifer were studied. Carvacrol and eugenol both exhibited dose-dependent antifungal activity against R. stolonifer, carvacrol at a concentration of 2 μl per plant and eugenol at a concentration of 4 μl per plant inhibited fungal growth completely. The two essential oils (EOs) increased cell membrane penetrability and caused the leakage of cytoplasm, nucleic acid and protein content. The observation using scanning electron microscopy and fluorescent microscopy showed modification of the hyphal morphology and breakage of the cell plasma membrane. Decreased ergosterol contents confirmed that the two EOs could destroy the membrane of R. stolonifer. For the in vivo test, the inhibition of soft rot disease and the induction of defence-related enzymes were investigated. Carvacrol and eugenol significantly reduced the incidence and severity of soft rot decay in inoculated peaches. The best treatments for controlling soft rot decay were obtained at 0·5 μl l for carvacrol and 1 μl l for eugenol. The activities of defence-related enzymes in peaches were also enhanced by fumigation with two EOs.
This study showed that carvacrol and eugenol could effectively inhibit the growth of R. stolonifer in vitro and successfully control the incidence of soft rot decay in honey peaches.
The above findings may be the main antifungal mechanism of carvacrol and eugenol on R. stolonifer. Furthermore, carvacrol and eugenol are helpful for their commercial application on the preservation of fresh fruit.
本研究旨在探究香芹酚和丁香酚抑制根霉的抗真菌机制及其对桃采后软腐病的防治效果。
为了探究其抗真菌机制，本研究分别研究了香芹酚和丁香酚对根霉菌丝生长、细胞质内容物渗漏、菌丝形态、细胞膜和膜组成的影响。香芹酚和丁香酚对根霉均表现出剂量依赖性的抗真菌活性，香芹酚在每株 2 μl 浓度下、丁香酚在每株 4 μl 浓度下完全抑制了真菌生长。两种精油（EOs）均增加了细胞膜通透性并导致细胞质、核酸和蛋白质内容物的渗漏。扫描电子显微镜和荧光显微镜观察显示，菌丝形态发生改变，细胞质膜破裂。麦角固醇含量的降低证实了两种 EOs 可以破坏根霉的细胞膜。在体内试验中，研究了软腐病的抑制和防御相关酶的诱导。香芹酚和丁香酚显著降低了接种桃的软腐病发病率和严重程度。控制软腐病的最佳处理方法为香芹酚 0.5 μl·l-1 和丁香酚 1 μl·l-1。两种 EOs 熏蒸还增强了桃中防御相关酶的活性。
本研究表明，香芹酚和丁香酚可有效抑制根霉的体外生长，并成功控制了油桃软腐病的发生。
上述发现可能是香芹酚和丁香酚对根霉的主要抗真菌机制。此外，香芹酚和丁香酚有助于其在新鲜水果保鲜方面的商业应用。
