Use of regional essential oils against Botrytis cinerea: new biocontrol strategies

ARECO VANESSA ANDREA; ALMIRÓN CAROLINA; ACHIMÓN FERNANDA; ZUNINO PAULA; YARYURA PABLO

Congreso; IV congreso Argentino de Biología y Tecnología Poscosecha; 2023

Botrytiscinerea is a phytopathogenic fungus, agent of gray mold, adisease that affects numerous species of agronomic importance such as tomato, andcauses considerable economic losses. It is mainly controlled by chemicalfungicides, but their inappropriate use has led to the development ofresistance. This has triggered the need for new environment-friendlyalternatives that could guarantee the maintenance of production. Plantessential oils (EOs) contain a plethora of compounds, with defensive functionsagainst various pathogens. Biodegradable and safe, EOs represent an alternativeto chemical pesticides. Aloysia polystachya is a native species of SouthAmerica, whose EO is rich in oxygenated monoterpenes, known for theirantimicrobial properties.  The aim of the present workwas to evaluate the antifungal activity of the EO present in two populations ofA. polystachya against B. cinerea. Materials and methods: The determination of the chemicalcomposition of the EOs was carried out by GC/MS. The antifungal activity of theEO from both populations was evaluated by the fumigant method, using fiveconcentrations (23.6, 47.2, 71, 94.5 and 189 µL/L of air). The effect of thedifferent concentrations of the EOs on conidia germination was determined. Thethree most effective concentrations in the invitro fumigant method were evaluated invivo in an infection model in cherry tomatoes, assessing the severity ofthe disease. The effect of these concentrations on quality parameters was alsostudied.  Thetrials were kept at 25 °C for 5 days. The effect of the EOs on germination wasevaluated 8 hours after the start of the treatment. Resultswere analyzed using one-way ANOVA and Kruskal-Wallis test using Infostatsoftware. Results: It was determined that the EOs used correspondto two different chemotypes, one whose main component was carvone, and theother with thujone as the main constituent. The EO rich in carvone produced theinhibition of mycelial growth for all the concentrations studied. Theantifungal activity of the thujone-rich chemotype was moderate, compared tothat of the carvone chemotype. All treatments significantly inhibited conidiagermination. In the in vivo infectionmodel, the carvone-rich chemotype significantly reduced disease severity atconcentrations of 94.5 and 189 µL/L of air, while the thujone-rich chemotypewas effective in reducing symptomatology at the highest evaluatedconcentration. The treatments did not affect the physicochemical parameters. Conclusions: Both chemotypes evaluatedshowed antifungal activity against B. cinerea, without affectingphysicochemical parameters of the fruits. The activity of the carvone-richchemotype was higher. These results allow us to postulate the use of these EOsas potential sustainable alternatives for the control of B. cinerea.