Toxigenic potential of Aspergillus section Flavi and Fusarium spp. and mycotoxin accumulation in maize across two contrasting growing seasons.

Maize is frequently contaminated by toxigenic fungi, mainly Fusarium spp. and Aspergillus section Flavi, which produce several mycotoxins and represent a major food safety concern. Climate change is expected to alter fungal communities in agroecosystems, potentially modifying mycotoxin contamination patterns in maize. This study compared mycotoxin accumulation and the mycotoxigenic potential of fungal isolates between two consecutive growing seasons characterized by contrasting climatic conditions (2023, hot/dry, and 2024, mild/wet) in maize samples from northeastern Spain. From 2023 and 2024, 853 Fusarium and 210 Aspergillus section Flavi isolates were obtained, and their toxigenic potential for fumonisins (FBs), deoxynivalenol (DON), zearalenone (ZEN), T-2/HT-2 toxins and aflatoxins (AFs) was assessed by HPLC, while natural mycotoxin contamination in the maize samples was determined by ELISA. The 2024 season was associated with a higher proportion of mycotoxin-producing Fusarium isolates and higher DON and ZEN concentrations in maize. DON and ZEN concentrations were positively correlated in both growing seasons, and the relative proportion of F. graminearum was positively associated with DON. F. proliferatum showed high FBs-producing potential in both seasons and a higher proportion of FBs-producing isolates than F. verticillioides. Although AFs-producing isolates were more frequent in 2023, AFs remained below the analytical LOD in all maize samples from both seasons. A. parasiticus showed high AF-producing capacity in vitro despite its relatively low occurrence. No significant correlations were detected between the in vitro toxigenic potential of fungal isolates and mycotoxin concentrations in the corresponding maize samples. Overall, contrasting seasonal conditions were associated with differences in toxigenic fungal profiles and mycotoxin accumulation in maize.