Genome-wide transcriptome analysis of toxigenic Fusarium verticillioides in response to variation of temperature and water activity on maize kernels.

Fusarium verticillioides is one of the important mycotoxigenic pathogens of maize since it causes severe yield losses and produces fumonisins (FBs) to threaten human and animal health. Previous studies showed that temperature and water activity (a w) are two pivotal environmental factors affecting F. verticillioides growth and FBs production during maize storage. However, the genome-wide transcriptome analysis of differentially expressed genes (DEGs) in F. verticillioides under the stress combinations of temperature and a w has not been studied in detail. In this study, DEGs of F. verticillioides and their related regulatory pathways were analyzed in response to the stress of temperature and a w combinations using RNA-Seq. The results showed that the optimal growth conditions for F. verticillioides were 0.98 a w and 25 °C, whereas the highest per-unit yield of the fumonisin B 1 (FB 1) was observed at 0.98 a w and 15 °C. The RNA-seq analysis showed that 9648 DEGs were affected by temperature regardless of a w levels, whereas only 218 DEGs were affected by a w regardless of temperature variations. Gene Ontology (GO) analysis revealed that a decrease in temperature at both a w levels led to a significant upregulation of genes associated with 24 biological processes, while three biological processes were downregulated. Furthermore, when a w was decreased at both temperatures, seven biological processes were significantly upregulated and four were downregulated. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that the genes, whose expression was upregulated when the temperature decreased, were predominantly associated with the proteasome pathway, whereas the genes, whose expression was downregulated when the a w decreased, were mainly linked to amino acid metabolism. For the FB 1 , except for the FUM15 gene, the other 15 biosynthetic-related genes were highly expressed at 0.98 a w and 15 °C. In addition, the expression pattern analysis of other biosynthetic genes involved in secondary metabolite production and regulation of fumonisins production was conducted to explore how this fungus responds to the stress combinations of temperature and a w. Overall, this study primarily examines the impact of temperature and a w on the growth of F. verticillioides and its production of FB 1 using transcriptome data. The findings presented here have the potential to contribute to the development of novel strategies for managing fungal diseases and offer valuable insights for preventing fumonisin contamination in food and feed storage. • Higher temperature (25 °C) and higher water activity (0.98 a w) favored the growth of Fusarium verticillioides • Lower temperature (15 °C) and higher water activity (0.98 a w) favored the fumonisin B 1 production in F. verticillioides • Secondary metabolite gene clusters were differentially expressed under temperature/water activity stresses. • The RNA-seq analysis provides gene groups for further investigation of fumonisin biosynthesis in F. verticillioides [ABSTRACT FROM AUTHOR]