Variation in systemic fungal endophyte infection and ploidy level in Festuca rubra L. across latitudes

DIRIHAN, S; GUNDEL, P. E.; HELANDER, M.; GARIBALDI L.A.; IRISARRI, G; SAIKKONEN, K.

Bangkok

Congreso; 10th International Mycological Congress; 2014

Endophyte infection frequencies and polyploidy in plant populations are well-documented but treated separately in past literature. In this study we analyzed geographic patterns of ploidy levels and systemic fungal endophyte infection frequencies of 29 Festuca rubra L. (well adapted species to wide range of environmental conditions) populations across latitudes from Spain to northernmost Finland and Greenland. We found that both endophyte infection frequencies and ploidy levels varied among and within populations. However, we could not detect clear geographic gradient in the frequencies of endophyte infected plants. Overall, 27 % of grasses were infected. Infection frequencies varied from 0 % to 81 %. Practically all examined plants collected from southern Finland and Greenland were endophyte-free. In contrast to infection frequencies, ploidy level seemed to be positively correlated with latitude. Most of the plants were hexaploids (2n=42; 83%), but also tetraploid (2n=28; 10 %) and octoploid (2n=56; 7 %) plants were detected. Tetraploidplants were particularly common in Spanish populations (86 %), and one of the populations in the northernmost Finland had only octoploid plants. Noteworthy is, however, that the positive correlation between ploidy level and latitude results from mostly tetraploid Spanish populations inthe south and one octoploid population collected in northernmost Finland . Thus, we conclude that latitude may only partly explain the frequencies of detected ploidy levels. The detected infection frequencies and ploidy levels probably mirror past distribution history of plants after glaciationperiod, and local adaptations to past or prevailing selection forces as suggested by geographic mosaic theory.