Abstract
Fusarium graminearum is one of the causal agents of Fusarium head blight and produces the trichothecene mycotoxin, deoxynivalenol (DON). Thioredoxin reductases (TRRs) play critical roles in the recycling of oxidized thioredoxin. However, their functions are not well known in plant pathogenic fungi. In this study, we characterized a TRR orthologue FgTRR in F. graminearum. The FgTRR-GFP fusion protein localized to the cytoplasm. FgTRR gene deletion demonstrated that FgTRR is involved in hyphal growth, conidiation, sexual reproduction, DON production, and virulence. The ΔTRR mutants also exhibited a defect in pigmentation, the expression level of aurofusarin biosynthesis-related genes was significantly decreased in the FgTRR mutant. Furthermore, the ΔTRR mutants were more sensitive to oxidative stress and aggravated apoptosis-like cell death compared with the wild type strain. Taken together, these results indicate that FgTRR is important in development and pathogenicity in F. graminearum.
Highlights
Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is an importantly destructive disease of wheat and barley worldwide (Goswami and Kistler, 2004)
One putative Thioredoxin reductases (TRRs) (FGSG_00871, designated as FgTRR) in F. graminearum was retrieved by BLAST search of the NCBI with the M. oryzae TRR1 (MGG_01284) as a query
The domain analysis showed that FgTRR was predicted to harbor all domains typical for the TRR family, including a FAD-binding domain I (GXGXX, where X is any amino acid), a FAD-binding domain II (GXFAXGDV), and a NADPH-binding domain (GGGXXA)
Summary
Fusarium head blight (FHB), caused mainly by Fusarium graminearum, is an importantly destructive disease of wheat and barley worldwide (Goswami and Kistler, 2004). The disease reduces wheat yield, and endangers the health of humans and animals because of consumption of mycotoxin-contaminated grain (McMullen et al, 1997; Goswami and Kistler, 2004, 2005; Desjardins and Proctor, 2007). The TRI gene cluster, including TRI5, TRI6, TRI10, and other TRI genes, are involved in DON synthesis in F. graminearum (Proctor et al, 1995; Brown et al, 2004; Alexander et al, 2009). TRR is a member of the pyridine nucleotide-disulfide oxidoreductase family and usually includes FAD-and NADPH-binding
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