Diversity of Mycobiota Associated with the Cereal Cyst Nematode Heterodera filipjevi Originating from Some Localities of the Pannonian Plain in Serbia

SIMPLE SUMMARY: Heterodera filipjevi, the cereal cyst nematode, is one of the most globally recognized and economically important nematodes on wheat. As some other cyst nematodes that are plant root parasites, the cysts of H. filipjevi survive in soil for years and shelter a large number of microbes. The aims of this study were to investigate the diversity of mycobiota associated with the cereal cyst nematode H. filipjevi, to infer phylogenetic relationships of the found mycobiota, and to explore the ecological connection between fungi and the field history, including the potential of fungi in bioremediation and the production of novel bioactive compounds. The study showed that the fungal species associated with the H. filipjevi cysts belong to diverse phyla, including Ascomycota, Basidiomycota, and Mucoromycota. The members of Ascomycota (Fusarium avenaceum, Sarocladium kiliense, Setophoma terrestris) are plant parasites, indicating that crops were host plants for fungal infection of recent origin. The members of Basidiomycota (Bjerkandera adusta, Cerrena unicolor, Trametes hirsuta, etc.) are wood-decay fungi, the presence of which in agricultural soil indicates that forests were the preceding plants. ABSTRACT: Cereals, particularly wheat, are staple food of the people from the Balkans, dating back to the Neolithic age. In Serbia, cereals are predominantly grown in its northern part between 44° and 45.5° N of the Pannonian Plain. One of the most economically important nematodes on wheat is the cereal cyst nematode, Heterodera filipjevi. Cysts of H. filipjevi survive in soil for years and shelter a large number of microorganisms. The aims of this study were to investigate the diversity of mycobiota associated with the cereal cyst nematode H. filipjevi, to infer phylogenetic relationships of the found mycobiota, and to explore the ecological connection between fungi and the field history, including the potential of fungi in bioremediation and the production of novel bioactive compounds. Cysts were isolated from soil samples with a Spears apparatus and collected on a 150-µm sieve. The cysts were placed on potato dextrose agar, and maintained for two weeks at 27°C. Following fungal isolation and colony growing, the fungal DNA was extracted, the ITS region was amplified, and PCR products were sequenced. The study showed that the isolated fungal species belong to diverse phyla, including Ascomycota, Basidiomycota, and Mucoromycota. Ascomycota is represented by the families Clavicipitaceae, Sarocladiaceae, Nectriaceae, and Phaeosphaeriaceae. Basidiomycota is represented by the families Cerrenaceae, Polyporaceae, Phanerochaetaceae, and Meruliaceae, and the order Cantharellales. The family Mortierellaceae represents Mucoromycota. The members of Ascomycota and Basidiomycota both depict the field history. Ascomycota indicate the fungal infection is of recent origin, while Basidiomycota point toward the preceding host plants, enabling the plant field colonization history to be traced chronologically.