Involvement of trichothecenes in fusarioses of wheat, barley and maize evaluated by gene disruption of the trichodiene synthase (Tri5) gene in three field isolates of different chemotype and virulence

Abstract

SUMMARY Fusarium graminearum is the main causative agent of Fusarium head blight on small grain cereals and of ear rot on maize. The disease leads to dramatic yield losses and to an accumulation of mycotoxins. The most dominant F. graminearum mycotoxins are the trichothecenes, with deoxynivalenol and nivalenol being the most prevalent derivatives. To investigate the involvement of trichothecenes in the virulence of the pathogen, the gene coding for the initial enzyme of the trichothecene pathway was disrupted in three field isolates, differing in chemotype and in virulence. From each isolate three individual disruption mutants were tested for their virulence on wheat, barley and maize. Despite the different initial virulence of the three wild-type progenitor strains on wheat, all disruption mutants caused disease symptoms on the inoculated spikelet, but the symptoms did not spread into other spikelets. On barley, the trichothecene deficient mutants showed no significant difference compared to the wild-type strains: all were equally aggressive. On maize, mutants derived from the NIV-producing strain caused less disease than their wild-type progenitor strain, while mutants derived from DON-producing strains caused the same level of disease as their progenitor strains. These data demonstrate that trichothecenes influence the virulence of F. graminearum in a highly complex manner, which is strongly host as well as moderately chemotype specific.

Fusarium species and chemotypes associated with fusarium head blight and fusarium root rot on wheat in Sardinia

“…This current study found that a certain chemotype was not associated with a particular disease type (FRR or FHB), implying the absence of a potential advantage of one chemotype over the other during establishment of FRR or FHB, at least based on these epidemiological data. This confirms that minor toxin type differences do not play a crucial role in disease establishment, but most probably have some specific role in disease progression (Maier et al, 2006).…”

The enzymatic detoxification of the mycotoxin deoxynivalenol: identification of DepA from the DON epimerization pathway

“…DON is secreted by the fungal pathogen and acts as a potent virulence factor, aiding in disease spread (Proctor et al ., 1995; Maier et al ., 2006). These diseases result in considerable economic losses due to reduced yields and diminished grain quality from mycotoxin contamination (Lee and Ryu, 2015; Zhang et al ., 2016).…”

Efficacy of Biological Control and Cultivar Resistance on <i>Fusarium</i> Head Blight and T-2 Toxin Contamination in Wheat

“…In wheat, the major mycotoxins associated with the disease are trichothecenes (T-2 toxin, deoxynivalenol and nivalenol) as well as zearalenone and fumonisins [4,5]. Trichothecenes are involved in inhibition of the host resistance reactions [6,7].…”