EVALUATION OF THE ANTIFUNGAL ACTIVITY OF REGIONAL ESSENTIAL OILS AGAINST Botrytis cinerea.

ACHIMÓN F; ZUNINO MP; ARECO V; YARYURA P

Congreso; XVII Congreso Argentino de Microbiología General; 2022

Botryitis cinerea is a phytopathogenic, necrotrophic fungus, agent of gray mold, a disease that affects numerous species of agronomic importance and causes considerable economic losses. Its main method of control is carried out by chemical fungicides, but their improper use has led to the development of resistance. Then, new forms of control are needed to guarantee the maintenance of yields. Plant essential oils (EOs) have in their composition terpenic compounds, phenylpropanoids, among others, with functions linked to the body´s defense against various pathogens. Its use as an alternative to chemical pesticides has multiple advantages, since they are biodegradable and safe for health. Aloysia polystachya is a herbaceous species, native of South America, whose EO is rich inoxygenated monoterpenes. The objective of the present work was to evaluate the antifungal activity of the EO of two populations of A. polystachya on B. cinerea. Materials and methods: The determination of the chemical composition of the EOs was carried out by GC/MS. The antifungal activity of the EO of both populations was evaluated by the fumigant method, using 5 concentrations (23.6, 47.2, 71, 94.5 and 189 μL/mL of air). In addition, the effect of the different concentrations ofthe EOs on the germination of conidia was evaluated and the morphology of the hyphae of B. cinerea under the different treatments was analyzed by means of scanning electron microscopy (SEM). The results were analyzed using one-way ANOVA and Kruskal-Wallis test using Infostat software. Results: It was determined that the EOs used correspond to two different chemotypes, one whose maincomponent was carvone, and the other with thujone as the main constituent. The EO rich in carvone produced the inhibition of mycelial growth for all the concentrations studied, the MIC being 71 μL/mL of air. The antifungal activity of the thujone-rich chemotype was moderate, compared to the carvonechemotype, and its MIC was determined for 189 μL/mL of air. All treatments significantly (P<0.05) inhibited conidia germination. The morphology of hyphae was considerably altered under the most effective treatments, observing contraction, flattening and emptying of them. Conclusions: Both chemotypes evaluated showed antifungal activity against B. cinerea, the activity of the carvone-rich chemotype being higher. A study of possible synergistic effects between both chemotypes is proposed for the future. These results allow us to postulate the use of these EOs as potential sustainable alternatives for the control of B. cinerea.