Hexokinase plays a critical role in deoxynivalenol (DON) production and fungal development in Fusarium graminearum

Abstract

Fusarium graminearum, the causal agent of Fusarium head blight, is a common pathogen on small grain cereals worldwide and produces various trichothecenes [deoxynivalenol (DON) is predominant] during infection. A previous study has revealed that DON production is positively correlated with the occurrence of carbendazim (MBC) resistance. Here, we identified and characterized two putative genes encoding hexokinase in F. graminearum (FgHXK1 and FgHXK2), which is a rate-limiting enzyme in DON biosynthesis. The expression level of hexokinase genes and the production of pyruvate, which is the precursor of DON, were up-regulated in the MBC-resistant strain, indicating that hexokinase genes might be involved in increased DON production. Phylogenetic and comparative analyses indicated that FgHXK1 was the predominant hexokinase gene. Gene disruption showed that ΔFgHXK1 severely affected DON production, indicating that FgHXK1 played a role in the regulation of DON biosynthesis. Morphological characterization showed that ΔFgHXK1 led to inhibited vegetative growth and conidiation. Sensitivity tests to MBC and various stresses indicated that both ΔFgHXK1 and ΔFgHXK2 mutants showed no significant difference from parental strains. Pathogencity assays showed that ΔFgHXK1 mutants lost virulence on wheat head and corn stigma; however, they showed no change in sexual reproduction. The FgHXK1-overexpressing transformants were obtained subsequently. Their pyruvate and DON production was confirmed to be increased, indicating that FgHXK1 positively regulated DON biosynthesis. Although additional defects appeared in overexpression mutants, MBC sensitivity showed no change. All of the results indicated that the transcriptional level of FgHXK1 regulated DON biosynthesis, but showed no direct relationship with MBC resistance.

Transcription factor ART1 mediates starch hydrolysis and mycotoxin production in Fusarium graminearum and F. verticillioides

“…The degradation of starch by amylases has been shown to affect aflatoxin and fumonisin production in Aspergillus flavus and F. verticillioides , respectively (Bluhm and Woloshuk, ; Fakhoury and Woloshuk, ). Recently, with regard to the genes involved in carbohydrate catabolism, two putative genes encoding hexokinase have been identified and characterized in F. graminearum (Zhang et al ., ). Of these two genes, deletion of FgHxk1 has been shown to result in a dramatically decreased level of DON production compared with the wild type, which is similar to a previous observation that the Δ hxk1 mutant of F. verticillioides produces 80% less FB 1 than the wild type (Kim and Woloshuk, ; Kim et al ., ).…”

“…Of these two genes, deletion of FgHxk1 has been shown to result in a dramatically decreased level of DON production compared with the wild type, which is similar to a previous observation that the Δ hxk1 mutant of F. verticillioides produces 80% less FB 1 than the wild type (Kim and Woloshuk, ; Kim et al ., ). Moreover, an FgHxk1 over‐expression strain has been shown to exhibit a remarkably high level of DON production (Zhang et al ., ). These results suggest that hexokinases encoded by Hxk1 play an important role in the transduction of external environmental cues for the regulation of secondary metabolites, such as trichothecenes and fumonisins.…”

2,4-Dihydroxy-7-methoxy-2 H -1,4-benzoxazin-3(4 H )-one (DIMBOA) inhibits trichothecene production by Fusarium graminearum through suppression of Tri6 expression

“…Ten microliters of this solution was spotted onto a TLC plate (2 μl aliquots), allowing the spots to dry between applications and then developed with ethyl acetate:toluene (3:1) and visualized as described by Takahashi-Ando et al (Zhang et al, 2015). Specific primers and a Universal ProbeLibrary probe (Roche) were designed at the Universal ProbeLibrary Assay Design Center of the manufacturer; specific primers qPCR-Tri6_P125_L (5"-TTACATGGAGGCCGAATCTC -3") and qPCR-Tri6_P125_R (5"-AGACGCAACTCGATCAAAGAG -3"), and a Universal ProbeLibrary probe #125…”

Microtubule‐assisted mechanism for toxisome assembly in Fusarium graminearum

“…All strains used in this study were grown and evaluated at 25 °C on PDA for mycelial growth and fungicide sensitivity assays. Mung bean broth medium was used for conidia culture (Zhang et al, 2016). For DON production analysis or toxisome observation, all strains were grown in TBI medium at 28 °C with agitation (175 rpm) in the dark for 7 days or 2 days, respectively (Tang et al, 2018).…”