Fusarium verticillioides genetics contribute to variability in fumonisin risk in maize

Fusarium verticillioides is a major fungal pathogen of maize and a primary cause of contamination of kernels with fumonisins-mycotoxins that threaten food safety and animal health. This study examined the influence of genetic diversity of F. verticillioides on the development of a fumonisin risk index. To do this, the effect of temperature (10-40 °C) on growth as assessed by ergosterol levels and fumonisin production in the fungus was assessed by liquid chromatography-mass spectrometry analysis, and the resulting data were subjected to a battery of analyses, including least squares means, Baranyi and Ratkowsky analyses. Although there was considerable variation among strains, the general trend was that growth of F. verticillioides occurred over a broader range of temperatures (15-35 °C) than fumonisin production (optimal at 20-30 °C). Growth and production were positively correlated (R² = 0.524 overall; R² = 0.78 at 30 °C), although the strength of this relationship varied with temperature. Production of the four major B-series fumonisin analogs (FB₁-FB₄) varied among strains, but for all strains the ratio of FB₁-FB₂ tended to increase with increasing temperature. These results demonstrate that fumonisin risk is shaped by a complex interplay of strain genetics and environmental conditions. The strain-dependent differences in growth kinetics, toxin production, and analog composition underscore the need for risk indices that integrate both environmental and genetic parameters to improve predictive models for mycotoxin contamination and targeted strategies to limit contamination during maize production and storage.