LE3 .A278 2022

2022

Walker, Allison
Faraone, Nicoletta

Acadia University

Bachelor of Science

Honours

Biology

Biology

Essential oils (EOs) are concentrated, volatile plant extracts which have widespread pharmacological, agricultural, and cosmetic applications. Thyme EO (TEO) and cinnamon EO (CEO) contain antifungal natural products which confer deterrent properties against plant pathogenic fungi, such as Botrytis cinerea Pers., the causative agent of grey mold of many plants. To determine the effects of these extracts on B. cinerea growth, TEO, CEO, and their main components – thymol (TL) and cinnamaldehyde (CA), respectively – were tested for fungistatic and fungicidal activity using an agar dilution method. Cores of B. cinerea mycelium were grown on potato dextrose agar infused with different concentrations of EOs. After 7 days, growth area was measured. Combined treatments (CEO+TEO, CA+TL) were also tested in this way to identify interactive effects between EOs or their components. Additionally, combinations of CA/ TL and the commercial antifungal natamycin were tested for interactive antifungal activity using a broth dilution method, where treatments were mixed with potato dextrose broth and B. cinerea spore suspension in a 96-well microplate and visually assessed for turbidity after 7 days. All individual treatments produced fungistatic effects and completely inhibited B. cinerea growth at 500 μg/mL. Cinnamon treatments (CEO, CA) were often fungicidal, possibly due to the destruction of the fungal cell wall by CA. Components tended to produce similar results to whole EOs, indicating that the antifungal properties of CEO and TEO can be primarily attributed to their main components. Contrary to previous reports, no interactive antifungal effects were found in any treatment combinations in the agar and broth dilution trials. This may be explained by variations in the chemical composition of the EOs used. These findings support previous documented antifungal activity in CEO, TEO, and their main components against B. cinerea, but does not confirm any antifungal interactions between these treatments or natamycin.

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https://scholar.acadiau.ca/islandora/object/theses:3809