COMMERCIAL ESSENTIAL OILS WITH ANTIFUNGAL EFFECT AGAINST THE MAIZE PHYTOPATHOGEN FUNGUS Fusarium verticillioides

ACHIMÓN, FERNANDA ; BRITO, VANESSA ; KRAPACHER, CLAUDIO; ARENA, JULIETA SOLEDAD; MERLO, CAROLINA; ZYGADLO, JULIO ALBERTO; PIZZOLITO, ROMINA P.

Congreso; IV Reunión Conjunta de Sociedades de Biología de la República Argentina; 2020

Fusarium verticillioides (Sacc.) is a fungal pathogen of maize and the major causal agent of stalk and ear rot worldwide. The application of syntheticfungicides is the most commonly used strategy to control food deterioration by fungi. However, these chemical substances proved to be toxic for theenvironment and organisms. In this context, there is an increasing public demand for the development of natural and safer antifungal agents, such asplant essential oils (EOs). Essential oils are hydrophobic substances of complex mixtures of volatile organic compounds. The aims of the presentwork were to study the chemical composition, antifungal, and anti-conidiation activities of Curcuma longa, Pimenta dioica, Rosmarinus officinalis,and Syzygium aromaticum EOs using a multivariate approach (Principal Component Analysis; PCA). The chemical composition of the EOs wasanalyzed by GC/MS. The antifungal and anti-conidiation activities were evaluated by the agar diffusion method. Different aliquots of each EO werediluted in Czapek Dox Agar (CDA) culture medium to achieve the following concentrations: 1000 ppm, 500 ppm, 250 ppm and 125 ppm. Data wereanalyzed by one-way analysis of variance (ANOVA) followed by a Multiple Comparison test. Syzygium aromaticum EO reported the highestantifungal effect, followed by P. dioica and to a lesser extent C. longa. The major compounds of these EOs were eugenol (88.7% in S. aromaticumand 16.7% in P. dioica), methyleugenol (53.09% in P. dioica), α-turmerone (44.7%), β-turmerone (20.67%), and Ar-turmerone (17.27%) in C. longa.The bioactivity of eugenol is attributable to the free ?OH group that act as the hydrophilic portion increasing its solubility in the plasma membraneand forming hydrogen bonds with the active sites of different enzymes. On the other hand, turmerones are ketones with an extra double bondbetween the alpha and beta carbons. These α,β-unsaturations increase the polarizability of the molecule, allowing them to bind with amino acids andnucleic acids and affecting different fungal metabolic pathways. Rosmarinus officinalis poorly inhibited fungal growth, but was the only EO thatinhibited conidial production, being its major components 1,8-cineole (53.48%), α-pinene (15.65%), and (?)-camphor (9.57%). Our results showedthat some compounds are capable of decreasing mycelial growth without affecting sporulation, and vice versa. However, not all the compounds of anEO are responsible for its bioactivity. In the present work, we were able to identify different major compounds or mix of major compounds that wereresponsible of antifungal and anti-sporulation effects. Further experiments combining these pure components are necessary in order to achieve ahighly bioactive plant-based formulation against the phytopathogen fungus F. verticillioides.