Abiotic conditions leading to FUM gene expression and fumonisin accumulation by Fusarium proliferatum strains grown on a wheat-based substrate

- We studied aW and temperature effects on growth, fumonisin B (FBs) production and FUM gene expression.
- F. proliferatum strains have similar growth profiles but different FBs production profiles.
- FUM8 and FUM19 genes showed similar expression behavior in all tested conditions.
- FUM gene expression at 25 °C correlated with fumonisin production, irrespective of aw.
- FBs production was lower at 15 °C, but FUM genes were expressed as at 25 °C.

Fusarium proliferatum produces fumonisins B not only on maize but also on diverse crops including wheat. Using a wheat-based medium, the effects of abiotic factors, temperature and water activity (aW), on growth, fumonisin biosynthesis, and expression of FUM genes were compared for three F. proliferatum strains isolated from durum wheat in Argentina. Although all isolates showed similar profiles of growth, the fumonisin production profiles were slightly different. Regarding FUM gene transcriptional control, both FUM8 and FUM19 expression showed similar behavior in all tested conditions. For both genes, expression at 25 °C correlated with fumonisin production, regardless of the aw conditions. However, at 15 °C, these two genes were as highly expressed as at 25 °C although the amounts of toxin were very weak, suggesting that the kinetics of fumonisin production was slowed at 15 °C. This study provides useful baseline data on conditions representing a low or a high risk for contamination of wheat kernels with fumonisins.