Inhibitory effect and mechanism of action of juniper essential oil on gray mold in cherry tomatoes

Abstract

Juniper essential oil (JEO), which is mostly known as an immune system booster and effective detoxifier, has substantial antimicrobial activity. A comparison of the inhibitory effects of three plant essential oils from juniper (Juniperus rigida), cedarwood (Juniperus virginiana), and cypress (Crupressus sempervirens) on four plant pathogenic fungi indicated that JEO was the most effective at inhibiting the growth of gray mold (Botrytis cinerea). Additional studies were subsequently conducted to explore the in vivo and in vitro antifungal activity and possible mechanism of JEO against B. cinerea. The results show that JEO inhibited the germination of spores and mycelial growth of B. cinerea in a concentration-dependent manner and exhibited strong inhibition when its concentration exceeded 10 μL/mL. JEO also significantly inhibited the incidence of disease and diameters of gray mold lesions on cherry tomato fruit (Solanum lycopersicum). After 12 h of treatment with JEO, the extracellular conductivity, and the contents of soluble protein, malondialdehyde, and hydrogen peroxide were 3.1, 1.2, 7.2, and 4.7 folds higher than those of the control group, respectively (P < 0.05), which indicated that JEO can damage membranes. Scanning electron microscopy observations revealed that JEO affected the morphology of mycelia, causing them to shrivel, twist and distort. Furthermore, JEO significantly improved the activities of the antioxidant-related enzymes superoxide dismutase and catalase but reduced the pathogenicity-related enzymes polygalacturonase (PG), pectin lyase and endoglucanase of B. cinerea (P < 0.05). In particular, PG was reduced by 93% after treatment with JEO for 12 h. Moreover, the 18 constituents of JEO were identified by gas chromatography/mass spectrometry (GC-MS) analysis, mainly limonene (15.17%), γ-terpinene (8.3%), β-myrcene (4.56%), terpinen-4-ol (24.26%), linalool (8.73%), α-terpineol (1.03%), o-cymene (8.35%) and other substances with antimicrobial activity. Therefore, JEO can be an effective alternative to prevent and control gray mold on cherry tomato fruit.

Enzymatic and proteomic exploration into the inhibitory activities of lemongrass and lemon essential oils against Botrytis cinerea (causative pathogen of gray mold)

“…The observation from this study is consistent with literature on the response of B. cinerea to EOs and other botanical fungicides ( Yang et al, 2020a ; Wu et al, 2022 ). For instance, Yang et al (2020a) demonstrated that treatment of B. cinerea with cembratrien-diols induced oxidative stress, which resulted in injured membrane system with a significant reduction of H 2 O 2 content in the mycelia.…”

“…For instance, Yang et al (2020a) demonstrated that treatment of B. cinerea with cembratrien-diols induced oxidative stress, which resulted in injured membrane system with a significant reduction of H 2 O 2 content in the mycelia. Similarly, H 2 O 2 content was found to be significantly lower in B. cinerea mycelia exposed to juniper EO compared to the untreated control during 12 h incubation period ( Wu et al, 2022 ). The balance between reactive oxygen species (ROS) production and scavenging capacity is crucial for any typical cellular processes.…”

“…Hydrogen peroxide is an important biomarker for the membrane lipids peroxidation, and it has been demonstrated to have a direct antifungal effect ( Qin et al, 2011 ; Wu et al, 2022 ). Results showed that exposure of B. cinerea to Le, Lg and Le + Lg EOs significantly reduced H 2 O 2 content in the fungal mycelia ( p < 0.005) at the end incubation day 7 ( Figure 1A ).…”

Antifungal Activity and Action Mechanisms of 2,4-Di-tert-butylphenol against Ustilaginoidea virens

“…MDA is one of the major markers for the peroxidation of membrane lipids and the damage degree of the cell membrane . The contents of MDA in U.…”

“…The plasma membrane acts as a barrier to protect the cell by regulating the exchange of compounds inside and outside of the cell and maintaining homeostasis of the intracellular environment. 18 The effect on the plasma membrane has been reported as one of the major action mechanisms of antifungal agents present in methyl thujate on Botrytis cinerea, 16 tea tree oil on Monilinia fructicola, 17 and linalool and pinosylvin monomethyl ether on Aspergillus flavus. 19,20 To evaluate the effects of 2,4-DTBP on the membrane integrity of U. virens, PI staining was performed with mycelia cultured in PSB medium with or without 2,4-DTBP.…”