Endophytic fungi in wild and cultivated grasses in Finland

We examined the occurrence of vertically via host seeds transmitted endophyte infections of 14 grass species in natural populations in Finland and totally 97 agricultural cultivars of 13 grass species. Although endophyte infections were widespread in native grass species, overall endophyte occurrence and frequencies were lower than published reports have suggested. In natural populations, 10 out of 14 grass species examined harbor fungal endophytes in their seeds. The highest species-specific mean incidences of endophyte infected plants in infected populations were found in Agrostis capillaris, Festuca arundinacea, F. ovina, F. pratensis, F. rubra and Phleum pratense (67%, 98%, 29%, 42%, 32% and 33%, respectively). Mean incidences were <20% in Dactylis glomerata, Deschampsia flexuosa, D. cespitosa and Elymus repens, and no infections were detected in Calamagrostis lapponica, C. epigejos, Alopecurus pratensis and Phalaris arundinacea. However, we detected a very high variation in infection incidences among natural populations and a large proportion of populations was, indeed, endophyte-free. This supports the ideas that 1) endophytic fungi provide selective advantage of infected grasses to their uninfected conspecifics in some habitats, and/or 2) fungi are occasionally transmitted horizontally by spores. In grass cultivars, endophyte infected seeds were detected only in F. pratensis and Lolium perenne, and endophyte frequencies were either very high or very low. Cultivars of 11 other grass species were endophyte-free.