Influence of Structure of Detrital Food Webs on Fusarium Head Blight of Winter Wheat

Anton A Goncharov,Olesya O Miroshnichenko,Valery A Ladatko,Valentina N Maygurova,Galina V Volkova,Arina D Kiseleva,Irina B Rapoport,Oksana L Rozanova,Kirill A Mashkov,Ivan V Sotnikov,Anastasia G Izvarina

doi:10.3390/agronomy12020393

Abstract

Conventional methods for Fusarium head blight (FHB) control are ineffective. A better understanding of the mechanisms linking the abundance of Fusarium species in soil before winter wheat flowering and mycotoxin content in mature grain may help to improve the effectiveness of methods for FHB control. In this study, we established a field experiment aimed to trace the impact of three types of organic mulch with different C:N ratios on the structure of detrital food webs and the manifestation of winter wheat FHB. T2-toxin content in grain was significantly higher in N-poor treatment (52.1 ± 0.2 µg g−1) compared to N-rich treatment (40.4 ± 1.6 µg g−1). The structure of detrital food webs in the studied treatments changed significantly after mulch addition; the abundance of soil saprophages and mycophages increased up to 50%. Based on the results of mixed-effects modeling, the abundance of herpetobionts and soil mesofauna were positively associated with an increase in Fusarium biomass in grain. The increase in the content of T2-toxin in the grain was associated with an increase in the abundance of earthworms and phytophagous macrofauna in the soil. Results suggest the existence of a previously undescribed mechanism for FHB infection by transfer of pathogenic spores by soil invertebrates, while the content of mycotoxins in grain can be triggered by the grazing activity of soil phytophagous invertebrates.

Highlights

Fusarium head blight (FHB) is an important disease that reduces cereal yields and leads to the accumulation of trichothecene mycotoxins (e.g., T2-toxin, deoxynivalenol, zearalenone) making the grain unacceptable for human consumption or animal feed [1,2,3]
A better understanding of the mechanisms linking the abundance of Fusarium species in soil before winter wheat flowering and mycotoxin content in mature grain may help to improve the effectiveness of methods for FHB control
Results suggest the existence of a previously undescribed mechanism for FHB infection by transfer of pathogenic spores by soil invertebrates, while the content of mycotoxins in grain can be triggered by the grazing activity of soil phytophagous invertebrates

Summary

Introduction

Fusarium head blight (FHB) is an important disease that reduces cereal yields and leads to the accumulation of trichothecene mycotoxins (e.g., T2-toxin, deoxynivalenol, zearalenone) making the grain unacceptable for human consumption or animal feed [1,2,3]. The main factors determining the likelihood of FHB occurrence in winter wheat include weather conditions just before and during flowering (warm and wet conditions are more favorable for FHB), plant variety (more or less susceptible to FHB), pre-crop rotation (cereals as pre-crop increase risk of FHB), and soil type [4,5]. Based on the results of a comprehensive meta-analysis, the use of fungicides from a class of compounds known as triazoles against FHB reduced the concentration of deoxynivalenol (DON) in wheat grain by 7.0–12.8% [7]. The high level of local species diversity of the genus Fusarium may be the main reason for the low sensitivity of this group to fungicides and antagonists [1]. Weed species within cereal crop rotations can serve as alternative hosts for pathogenic Fusarium species as was shown for F. graminearum causing FHB of wheat [11]. The development of new wheat varieties resistant to FHB is complicated by the lack of donors of robust genetic resistance to FHB among known wheat varieties [12]

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