New strategies alternatives to synthetic fungicides to control postharvest fungal pathogens

BENJAMIN BERTINI; LUCIANA CERIONI; PAULA PATERLINI; ANALIA ALVAREZ; CINTIA MARIANA ROMERO; SABRINA VOLENTINI

Mendoza

Congreso; Congreso SAIB 2022; 2022

SAIB

Tucuman is the main national citrus and blueberries producer, but both activities must face important economic losses due to postharvest fungal diseases. To control these diseases, chemical fungicides are applied and, although they are very efficient, have associated serious problems for the consumers and environment health, as well as the increase of fungicide resistant isolates. For this reason, there is a permanent search for new alternative control strategies, both evaluating new compounds and edible coatings, that which provide support and durability to postharvest treatments. In this work we evaluate the antifungal action of silver nanoparticles (NP-Ag) obtained by green synthesis from cultures of Streptomyces sp. M7 and a new edible coating, Levan, a natural fructan with 2,6-β bonds produced by the Bacillus sp. Mcn4. For both compounds, we determined the effect over conidial germination and micellar growth inhibition of citrus pathogens such as Penicillium digitatum and P. Italicumitalicum, sensitive and resistant to fungicides and Geotrichum citr-aurantii and blueberries pathogens such as Botritys cinerea and Alternaria. sp. The results showed that Np-Ag 2mg/ml of were able to inhibit mycelial growth for all pathogens. Furthermore, conidial germination was affected using Np-Ag 0.5 mg/ml, showing conidial and hyphae deformations. On the other hand, Levan 5% had no antimicrobial action in vitro against the pathogens. To validate their activity as edible coatings, we evaluated green mold incidence in lemons artificially inoculated with P. digitatum and treated with levan alone or as a vehicle for the administration of potassium sorbate (SK), a GRAS salt with recognized antifungal action. The results showed that the application of 1% levan and 6% SK reduced the diseases incidence by 80%. Here we demonstrate that the application of silver nanoparticles or levan, as natural edible coatings, would be a promising compound to development new alternative strategies applied in postharvest to control fungal diseases.