What influences the composition of fungi in wheat grains?

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 <em>Pyrenophora tritici-repentis</em>, <em>Alternaria</em> spp., <em>Arthrinium</em> spp., and <em>Fusarium avenaceum</em>. Higher amounts of precipitation increased the infection of grains with <em>Fusarium</em> fungi. Seven species of <em>Fusarium</em> were identified in the grain samples: <em>F. avenaceum</em>, <em>F. poae</em>, <em>F. graminearum</em>, <em>F. culmorum</em>, <em>F. acuminatum</em>, <em>F. sporotrichioides</em>, and <em>F. tricinctum</em>. The soil tillage method and crop rotation did not influence the total incidence of <em>Fusarium</em> 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 <em>F. graminearum</em> and, consequently, the accumulation of mycotoxins.