Abstract
Fusarium verticillioides is the major maize pathogen associated with ear rot and stalk rot worldwide. Fumonisin B1 (FB1) produced by F. verticillioides, poses a serious threat to human and animal health. However, our understanding of FB1 synthesis and virulence mechanism in this fungus is still very limited. Glycosylation catalyzed by glycosyltransferases (GTs) has been identified as contributing to fungal infection and secondary metabolism synthesis. In this study, a family 2 glycosyltransferase, FvCpsA, was identified and characterized in F. verticillioides. ΔFvcpsA exhibited significant defects in vegetative growth. Moreover, ΔFvcpsA also increased resistance to osmotic and cell wall stress agents. In addition, expression levels of FUM genes involved in FB1 production were greatly up-regulated in ΔFvcpsA. HPLC (high performance liquid chromatography) analysis revealed that ΔFvcpsA significantly increased FB1 production. Interestingly, we found that the deletion of FvCPSA showed penetration defects on cellophane membrane, and thus led to obvious defects in pathogenicity. Characterization of FvCpsA domain experiments showed that conserved DXD and QXXRW domains were vital for the biological functions of FvCpsA. Taken together, our results indicate that FvCpsA is critical for fungal growth, FB1 biosynthesis and virulence in F. verticillioides.
Highlights
The filamentous ascomycete Fusarium verticillioides is one of the most important fungal pathogens causing stalk and ear rot on maize [1]
Our results confirmed that FvCpsA played a vital role in fumonisin B1 (FB1) biosynthesis, FUM genes expression, fungal growth, stress response and virulence in F. verticillioides. These findings provide a clear indicator for the exploration of glycosylation modification in the regulation of FB1 production in F. verticillioides, which is conducive to establishing efficient control strategies for FB1 management
Using A. nidulans CpsA protein sequences as queries, homology searches in the F. verticillioides genome sequence database led to the recognition of a predicted gene, FVEG_00488, designated as FvCPSA in this study
Summary
The filamentous ascomycete Fusarium verticillioides is one of the most important fungal pathogens causing stalk and ear rot on maize [1]. F. verticillioides results in substantial maize yield losses. Various types of mycotoxins, such as fumonisins, fusarins and fusaric acid produced by F. verticillioides, lead to severe human and animal diseases [2]. Fumonisins are the most notorious mycotoxins, which have been widely distributed among corn and corn-based foods [3,4]. The mitogen-activated protein kinase (MAPK) signaling pathways have been shown to regulate FB1 production in F. verticillioides [8]. Recent studies have shown that post-translational modifications, such as acetylation, methylation and phosphorylation, play a critical role in FB1 production [9]. The molecular mechanisms underlying the regulation of FB1 are still unclear
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