Occurrence of Fusarium Mycotoxins and Their Modified Forms in Forage Maize Cultivars.

Tim Birr,Joseph-Alexander Verreet,Mario Hasler,Frank D Sönnichsen,Holger Klink,Sarah De Saeger,Nils Preußke,Tolke Jensen,Marthe De Boevre

doi:10.3390/toxins13020110

Abstract

Forage maize is often infected by mycotoxin-producing Fusarium fungi during plant growth, which represent a serious health risk to exposed animals. Deoxynivalenol (DON) and zearalenone (ZEN) are among the most important Fusarium mycotoxins, but little is known about the occurrence of their modified forms in forage maize. To assess the mycotoxin contamination in Northern Germany, 120 natural contaminated forage maize samples of four cultivars from several locations were analysed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) for DON and ZEN and their modified forms deoxynivalenol-3-glucoside (DON3G), the sum of 3- and 15-acetyl-deoxynivalenol (3+15-AcDON), α- and β-zearalenol (α-ZEL, β-ZEL). DON and ZEN occurred with high incidences (100 and 96%) and a wide range of concentrations, reaching levels up to 10,972 and 3910 µg/kg, respectively. Almost half of the samples (46%) exceeded the guidance value in complementary and complete feeding stuffs for ZEN (500 µg/kg), and 9% for DON (5000 µg/kg). The DON related mycotoxins DON3G and 3+15-AcDON were also present in almost all samples (100 and 97%) with amounts of up to 3038 and 2237 µg/kg and a wide range of concentrations. For the ZEN metabolites α- and β-ZEL lower incidences were detected (59 and 32%) with concentrations of up to 423 and 203 µg/kg, respectively. Forage maize samples were contaminated with at least three co-occurring mycotoxins, whereby 95% of all samples contained four or more mycotoxins with DON, DON3G, 3+15-AcDON, and ZEN co-occurring in 93%, together with α-ZEL in 57% of all samples. Positive correlations were established between concentrations of the co-occurring mycotoxins, especially between DON and its modified forms. Averaged over all samples, ratios of DON3G/DON and 3+15-AcDON/DON were similar, 20.2 and 20.5 mol%; cultivar-specific mean ratios ranged from 14.6 to 24.3 mol% and 15.8 to 24.0 mol%, respectively. In total, 40.7 mol% of the measured DON concentration was present in the modified forms DON3G and 3+15-AcDON. The α-ZEL/ZEN ratio was 6.2 mol%, ranging from 5.2 to 8.6 mol% between cultivars. These results demonstrate that modified mycotoxins contribute substantially to the overall mycotoxin contamination in forage maize. To avoid a considerable underestimation, it is necessary to analyse modified mycotoxins in future mycotoxin monitoring programs together with their parent forms.

Highlights

Maize (Zea mays L.) is one of the most important cereal crops worldwide and grown over a variety of climatic conditions
To assess the mycotoxin contamination in Northern Germany, 120 natural contaminated forage maize samples of four cultivars from several locations were analysed by liquid chromatography-high resolution mass spectrometry (LC-HRMS) for DON and ZEN and their modified forms deoxynivalenol-3-glucoside (DON3G), the sum of 3- and 15-acetyl-deoxynivalenol (3+15-AcDON), α- and β-zearalenol (α-ZEL, β-ZEL)
We investigated the occurrence of DON and ZEN along with their major modified forms DON3G, 3- and 15-AcDON, α- and β-ZEL in 120 naturally contaminated forage maize samples of four cultivars collected at eight trial locations in Northern Germany from the 2017 harvest in order to obtain a more comprehensive picture of the natural co-contamination of forage maize with DON and ZEN and their modified forms

Summary

Introduction

Maize (Zea mays L.) is one of the most important cereal crops worldwide and grown over a variety of climatic conditions. Maize as well as small-grain cereals like wheat, barley, and oats are susceptible to infections by fungi of the genus Fusarium. These fungi are known as plurivorous pathogens of various crops worldwide, which attack a range of plant parts and stages [5,6]. In European maize growing areas, Fusarium diseases of maize are caused by several co-occurring species, e.g., F. graminearum, F. culmorum, F. avenaceum, mainly associated with temperate and moist environmental conditions in North and Central Europe, and F. verticillioides, F. temperatum, F. proliferatum, commonly associated with warm and dry conditions in Southern European regions [6,7,8,9,10,11]. Infections of maize plants with phytopathogenic Fusarium species may occur throughout the whole vegetation period, whereby different pathways can be used to infect the maize plant, causing several rot diseases of ears and kernels (ear rot), rudimentary ears, roots, stems (stem rot), seeds, and seedlings [12]

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