Quantification of Trichothecene-Producing Fusarium Species in Harvested Grain by Competitive PCR To Determine Efficacies of Fungicides against Fusarium Head Blight of Winter Wheat

Abstract

We developed a PCR-based assay to quantify trichothecene-producing Fusarium based on primers derived from the trichodiene synthase gene (Tri5). The primers were tested against a range of fusarium head blight (FHB) (also known as scab) pathogens and found to amplify specifically a 260-bp product from 25 isolates belonging to six trichothecene-producing Fusarium species. Amounts of the trichothecene-producing Fusarium and the trichothecene mycotoxin deoxynivalenol (DON) in harvested grain from a field trial designed to test the efficacies of the fungicides metconazole, azoxystrobin, and tebuconazole to control FHB were quantified. No correlation was found between FHB severity and DON in harvested grain, but a good correlation existed between the amount of trichothecene-producing Fusarium and DON present within grain. Azoxystrobin did not affect levels of trichothecene-producing Fusarium compared with those of untreated controls. Metconazole and tebuconazole significantly reduced the amount of trichothecene-producing Fusarium in harvested grain. We hypothesize that the fungicides affected the relationship between FHB severity and the amount of DON in harvested grain by altering the proportion of trichothecene-producing Fusarium within the FHB disease complex and not by altering the rate of DON production. The Tri5 quantitative PCR assay will aid research directed towards reducing amounts of trichothecene mycotoxins in food and animal feed.

Impact of Fungicide Timing on the Composition of the Fusarium Head Blight Disease Complex and the Presence of Deoxynivalenol (DON) in Wheat

“…This observation was corroborated by several scientific reports (Edwards et al 2001;Paul et al 2008;Pirgozliev et al 2002). Finally for prothioconazole Paul et al (2008) mentioned decreased DON levels.…”

“…For tebuconazole it is generally accepted that it causes a reduction in the biosynthesis or DON level (Edwards et al 2001;Haidukowski et al 2005;Ioos et al 2005;Paul et al 2008;Simpson et al 2001;Zhang et al 2009a) and the trichothecene nivalenol (NIV) (Ioos et al 2005). Information on another triazole fungicide propiconazole is contradictionary.…”

Fusarium spp. Contamination of Wheat, Maize, Soybean, and Pea Grain in Croatia

“…Theoretically, Fusarium mycotoxins can be produced on every plant and all plant parts infested by toxigenic Fusarium species. Over the last ten years, detection of mycotoxins and toxigenic Fusarium species has advanced signifi cantly with the development of PCR-based techniques (13)(14)(15)(16). However these techniques are still not widely used because they are expensive.…”

Fusarium head blight and associated mycotoxin occurrence on winter wheat in Luxembourg in 2007/2008

“…High disease pressure of Fusarium is not automatically related to a higher DON content (Everlange in 2008, severity: 36% and DON: 301 mg/kg). Edwards et al (2001) suggested that some pathogens do not produce mycotoxins, which means that mycotoxin contamination is not related to visual symptoms of disease severity. Opinions also vary strongly on the existence of a relationship between DON and the amount of FHB pathogen (Isebaert et al, 2009).…”