In: Sydowia 78, (2026): 283-290; ISSN 0082-0598, DOI 10.12905/0380.sydowia78-2026-0283, Published online on january 12th, 2026

Fungal endophytes of roots can exhibit host-specificity through overwintering

Anna Liisa Ruotsalainen, Tiina Sauvola, Anna Maria Pirttilä & Mysore Vishakantegowda Tejesvi

Ecology and Genetics Research Unit, POB 3000, FI-90014 University of Oulu, Finland e-mail: annu.ruotsalainen@oulu.fi

Ruotsalainen A.L., Sauvola T., Pirttilä A.M. & Tejesvi M.V. (2026) Fungal endophytes of roots can exhibit host-specificity through overwintering. – Sydowia 68: 283–290.

Decaying roots may play a role in endophytic fungal survival through an unfavourable season. We investigated root fungal endophytic communities of Avenella flexuosa and Lysimachia europaea prior to and after a simulated winter. To assess the viability of the endophytic fungi, we used a culture-based approach. We found that the total number of root fungal isolates, the number of isolate morphotypes and the isolate morphotype communities remained host-species-specific through overwintering. Both the total number of fungal isolates and thenumber of isolate morphotypes were higher in Avenella than in Lysimachia both prior to and after the simulated winter. The winter simulation also increased both the total number of isolates and the number of isolate morphotypes in Avenella, whereas in Lysimachia, the simulated winter had no effect. The root fungal isolate morphotype community was more heterogeneous in Avenella than in Lysimachia. An isolate morphotype identified as Phialocephala fortinii, a dark septate endophyte, dominated the root culturable fungal community in Lysimachia. Our results suggest that the endophytic fungi of Avenella and Lysimachia have potential to survive in the decaying root fragments and that the fungal community remains host-species-specific until the next growing season.

Keywords: culturing methods, dark septate endophytes, Phialocephala fortinii, seasonality, symbiosis.