What influences the composition of fungi in wheat grains?

Biruta Bankina,Dāvids Fridmanis,Ance Roga,Ingrīda Neusa-Luca,Gunita Bimšteine

doi:10.5586/aa.1726

Abstract

Wheat grains are inhabited by different fungi, including plant pathogens and fungi – mycotoxin producers. The composition of seed mycobiota can be influenced by different factors, including agronomic practices, but the results are still contradictory. The aim of this study was to evaluate the mycobiota of wheat grains depending on agroecological conditions. Wheat grains were obtained from a two-factorial field trial: A – tillage system (A1 – ploughing at a depth of 22–24 cm; A2 – harrowing at a depth of up to 10 cm); B – crop rotation (B1 – continuous wheat; B2 – oilseed rape and wheat; B3 – crop rotation). The mycobiota of grain were determined by mycological and molecular methods. The most abundant and widespread of the mycobiota were Pyrenophora tritici-repentis, Alternaria spp., Arthrinium spp., and Fusarium avenaceum. Higher amounts of precipitation increased the infection of grains with Fusarium fungi. Seven species of Fusarium were identified in the grain samples: F. avenaceum, F. poae, F. graminearum, F. culmorum, F. acuminatum, F. sporotrichioides, and F. tricinctum. The soil tillage method and crop rotation did not influence the total incidence of Fusarium spp., but the abundance of a particular species differed depending on agronomic practice. The research suggests that continuous wheat sowing under conditions of reduced soil tillage can increase the level of risk of grain infection with F. graminearum and, consequently, the accumulation of mycotoxins.

Highlights

Wheat is one of the most important and economically beneficial crops in Latvia
The majority of isolates, which belonged to the Fusarium/Gibberella complex or to Microdochium nivale/majus, were included in the group of moderate occurrence (RD = 2.55–9.28%); the rest of the fungi were found only in some cases (Fig. 1)
During the 5 years of investigation, fungi from which was to be expected because this fungus is the causal agent of one of the most important wheat diseases in Latvia and Lithuania [10]

Summary

Introduction

Investigations of the risk factors that can influence wheat production have become increasingly crucial for the economy of the country. Wheat grains are inhabited by different fungi, yet the role of many of them in the development and health of wheat plants is not clear [1]. Numerous fungi colonize different parts of the wheat plant, including the ears and grains, without causing any disease [2]. Seed mycobiota can significantly influence the cultivation of wheat. Many wheat pathogens (Pyrenophora tritici-repentis, Parastagonospora nodorum, etc.) survive in the grains. The most serious problem is grain contamination by the causal agents of wheat head blight, mainly fungi from the Fusarium/Gibberella genera. Part of the species has been recognized as Gibberella because of its ability to produce ascospores, but the other part still bears the name Fusarium. The name Fusarium is used for the purpose of simplicity

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Conclusion