The Histone Deacetylase Inhibitor Trichostatin-A Modifies the Expression of Trichothecene Mycotoxin Regulatory Gene Tri5 in Fusarium graminearum

Abstract

Background: Fusarium graminearum is the causal agent of Fusarium Head Blight (FHB) on wheat and produces deoxynivalenol (DON), known to cause extreme human and animal toxicosis. This species' genome contains genes involved in plant-pathogen interactions and regulated by chromatin modifications. Moreover, histone deacetylase inhibitors (HDACIs), including trichostatin A (TSA), have been employed to study gene transcription regulation because they can convert the structure of chromatin.

Objectives: The current study was designed to evaluate the effects of TSA on histone deacetylase (HDAC) and, trichodiene synthase (Tri5) gene expression in toxigenic and non-toxigenic F. graminearum isolates.

Materials and methods: The mycelia were grown on potato dextrose broth (PDB) culture media supplemented with two concentrations of TSA and dimethyl sulfoxide (DMSO) (3 and 10 µg. mL^-1) for 48 h, 72 h, and 96 h. Then, the mRNA levels were estimated via real-time quantitative reverse transcription-polymerase chain reaction (real-time qRT-PCR).

Results: We found that the levels of HADC and Tri5 varied over time and dosage in response to the use of TSA. The toxigenic isolate showed an increase in the Tri5 expression when treated with TSA, with the highest levels monitored when the concentration of the substance was 3 µg. mL^-1 at 48 h. The non-toxigenic isolate also showed high levels of HDAC and Tri5 expression in the presence of TSA, but a sharp decrease in the Tri5 transcription was observed at 72 h when grown on culture media containing 10 µg. mL^-1 of TSA.

Conclusion: Overall, our results suggest a mode of DON biosynthesis regulation in F. graminearum by chromatin modifications that may help us offer new strategies for tackling fungal infections.

Keywords: Chromatin; Deacetylation; Deoxynivalenol; Epigenetics; Fungi.

Figure 1

Electrophoretic pattern of PCR products for F. graminearum isolates. A) Using HDACF/HDACR primers. L: 100 bp molecular weight marker (Thermo Scientific, USA); N: Negative control (without DNA template); 1-15: Different isolates of F. graminearum. B) Using Tri5F/Tri5R primers. L: 100 bp molecular weight marker (Thermo Scientific, USA); N: Negative control (without DNA template); 1-15: Different isolates of F. graminearum.

Figure 2

Electrophoretic pattern of PCR products for F. graminearum isolates using Tri13F/Tri13DONR primers. L: 100 bp molecular weight marker (Thermo Scientific, USA); N: Negative control (without DNA template); 1-15: Different isolates of F. graminearum

Figure 3

Reverse transcription PCRs (RT-PCRs) of respective genes. A) Minus reverse transcriptase PCR (without RT enzyme) products of UBH gene for F. graminearum isolates treated with TSA. L: 100 bp molecular weight marker (Thermo Scientific, USA); N: Negative control (without RNA template). 1-5: Different RNA samples of F. graminearum. B) RT-PCR products of Tri5, HDAC, and UBH genes for F. graminearum isolates treated with TSA. L: 100 bp molecular weight marker (Sinaclon, Iran); N: Negative control (without cDNA template).

Figure 4

The effects of two different concentrations of TSA on the expression of HDAC, in toxigenic (group 1) and non-toxigenic (group 2) isolates of F. graminearum at 48 h, 72 h, and 96 h. The significant difference was determined by p < 0.01**, 0.01 < p < 0.05* vs. control. A horizontal line appears on the statistical comparison bar, showing no significant difference (NS)

Figure 5

The effects of two different concentrations of TSA on the expression of Tri5, in toxigenic (group 1) and non-toxigenic (group 2) isolates of F. graminearum at 48 h, 72h, and 96 h. The significant difference was determined by p < 0.01**, 0.01 < p < 0.05* vs. control. A horizontal line appears on the statistical comparison bar, showing no significant difference (NS)