Cupressus sempervirens essential oils and their major compounds successfully control postharvest grey mould disease of tomato

Medicinal plants generally produce many secondary metabolites which constitute an important source of many bioactive molecules. Among them Cupressus sempervirens is recognized by its richness in essential oil with antimicrobial properties. The aim of this study is to use C. sempervirens essential oil or its bioactive components as an alternative to synthetic fungicides currently used to control Botrytis cinerea. Essential oils of C. sempervirens were extracted at vegetative, flowering and fructification stages and a total of 54 compounds were identified by chromatography-mass spectrometry. Essential oils composition varied with the phenological stage and the main chemical classes were sesquiterpene hydrocarbons (59.59%-64.5%) with the most representative compounds being germacrene D (18.38%-24.82%) and those of the monoterpene hydrocarbons class (16.63%-26.5%) with a-pinene as the most representative compound (14.75%-22.92%). The in vitro antifungal tests against B. cinerea showed that the three studied essential oils inhibit mycelia growth with the highest activity observed at flowering stage. The antifungal activity of some pure compounds (alpha-pinene, alpha-cedrol and beta-caryophyllene) alone or combined according to their proportions in the natural essential oil showed that alpha-pinene combined with beta-caryophyllene provided the highest antifungal activity at a concentration as low as 0.12 mg/mL as compared to that of the chemical fungicide used as a positive control. Microscopic observation showed that essential oil at flowering stage induced swelling and crumbling of B. cinerea conidia. The pulverization of C. sempervirens essential oils on tomato fruits at 1 mg/mL inhibited 54% of B. cinerea infection which constitute a promising safe product for the biocontrol of the post-harvest disease Botrytis cinerea during storage and transport of tomato.