MFS Transporters and GABA Metabolism Are Involved in the Self-Defense Against DON in Fusarium graminearum

Abstract

Trichothecene mycotoxins, such as deoxynivalenol (DON) produced by the fungal pathogen, Fusarium graminearum, are not only important for plant infection but are also harmful to human and animal health. Trichothecene targets the ribosomal protein Rpl3 that is conserved in eukaryotes. Hence, a self-defense mechanism must exist in DON-producing fungi. It is reported that TRI (trichothecene biosynthesis) 101 and TRI12 are two genes responsible for self-defense against trichothecene toxins in Fusarium. In this study, however, we found that simultaneous disruption of TRI101 and TRI12 has no obvious influence on DON resistance upon exogenous DON treatment in F. graminearum, suggesting that other mechanisms may be involved in self-defense. By using RNA-seq, we identified 253 genes specifically induced in DON-treated cultures compared with samples from cultures treated or untreated with cycloheximide, a commonly used inhibitor of eukaryotic protein synthesis. We found that transporter genes are significantly enriched in this group of DON-induced genes. Of those genes, 15 encode major facilitator superfamily transporters likely involved in mycotoxin efflux. Significantly, we found that genes involved in the metabolism of gamma-aminobutyric acid (GABA), a known inducer of DON production in F. graminearum, are significantly enriched among the DON-induced genes. The GABA biosynthesis gene PROLINE UTILIZATION 2-2 (PUT2-2) is downregulated, while GABA degradation genes are upregulated at least twofold upon treatment with DON, resulting in decreased levels of GABA. Taken together, our results suggest that transporters influencing DON efflux are important for self-defense and that GABA mediates the balance of DON production and self-defense in F. graminearum.

Independent losses and duplications of autophagy‐related genes in fungal tree of life

“…S3). Growth rate, infection assays with flowering wheat heads, disease index, conidiation and conidium germination were assayed as previously described (Wang et al, 2011;Cao et al, 2016;Wang et al, 2018). Perithecium formation, ascus development, ascospore germination and ascospore releasing were assayed on carrot agar plates as described (Cavinder et al, 2012;Luo et al, 2014;Yin et al, 2018).…”

Genome Sequencing and Analysis of the Hypocrellin-Producing Fungus Shiraia bambusicola S4201

“…These secondary metabolites, particularly mycotoxins in S. bambusicola, may be responsible for its adaptation to an exclusively parasitic life cycle. There are mainly two transport systems, ABC-transporter (Gao et al, 2019) and MFS-transporter (Wang et al, 2018). These analyses provide some insights into the role of CAZymes and secondary metabolites in the parasitic lifestyle of S. bambusicola S4201.…”

A Genome-Wide Association Study Identifies SNP Markers for Virulence in Magnaporthe oryzae Isolates from Sub-Saharan Africa

“…The 9 respective genes identified in SSA M. oryzae isolates are: (1) MGG_06041 , a Rhamnogalactouronan lyase (Quoc and Chau, 2017) that recognizes and cleaves the ∞-1,4 glycosidic bonds in the backbone of rhamnogalactouronan-I, a major component of the plant cell wall polysaccharide, pectin. (2) the MFS transporter MGG_10131 , transporters such as these have recently been shown to be important for production of mycotoxins such as deoxynivalenol (DON) in Fusarium graminearum (Wang et al, 2018). DON plays a key role in infection of host plants (Wang et al, 2018).…”