Exploration of the antifungal potential of aqueous extracts from two agave species against major postharvest diseases in apples

The apple tree, belonging to the Rosaceae family producing pome fruit, holds global economic significance. Despite this, apples face considerable postharvest disease challenges, particularly blue mold caused by Penicillium expansum and gray mold Botrytis cinerea. Synthetic fungicides are traditionally used for control, but their drawbacks necessitate exploring environmentally friendly alternatives. The current research investigates the antifungal activity of Agave americana and Agave sisalana aqueous extracts against these post-harvest diseases. In vitro tests demonstrated a concentration-dependent antifungal effect, with A. americana completely inhibiting mycelial growth and spore germination at 50 g L-1. A. sisalana exhibited a 75% reduction at the same concentration. A. americana at 6 g L-1 inhibited 50% of spore germination, while A. sisalana at 8 and 9 g L-1 achieved the same for B. cinerea and P. expansum. Regarding In vivo tests, both extracts reduced infection severity, particularly A. americana, which lowered gray mold and blue mold incidences to 23 and 26%. High polyphenol and flavonoid content in Agave extracts likely contributed to their efficacy. Phytochemical analyses identified 35 metabolites, including citric acid and piscidic acid, which are potential inhibitors of the fungal cell enzyme sterol 14 alpha-demethylase (CYP51), according to the results of molecular Docking analyses. Similarly, FTIR results indicated compounds with significant antimicrobial activity. Importantly, these biological treatments preserved apple quality during storage, suggesting their potential as effective and sustainable alternatives to synthetic fungicides.