During establishment and subsequent growth, corticolous lichen fungi are subjected to the chemical composition and pH of the stemflow, which depend on the water-soluble compounds released from the bark. The present study explored the use of sporeshot isolation to test the effect of bark extracts on germination and initial mycelium growth. The pH, phenolic content and glucose equivalents of the bark extracts were also related to spore germination. Bark samples from Acer pseudoplatanus, Alnus glutinosa, Betula pendula, Fagus sylvatica, Fraxinus excelsior, Quercus robur and Tilia cordata were collected at two heights. We extracted water-soluble compounds and isolated fungal spore groups from Xanthoria parietina (L.) Th. Fr. in vitro on water agar mixed with extracts. Spores germinated and grew on pure water agar (control) and media with extracts from Acer, Betula and Fagus. Growth was significantly lower on Acer than on Betula, Fagus and controls. No germination took place on the remaining media suggesting a strong inhibitory effect of Fraxinus, Quercus, Tilia and Alnus. Germination occurred within a week and was an all-or-none response. The mycelia grew slowly, and diameters within 90 days ranged from 0.25 to 3.05 mm. All bark extracts that allowed germination showed a pH above 5.1 and relatively low amounts of phenols and glucose equivalents. This suggests that low pH and strong concentrations of dissolved compounds in the stemflow may prevent lichen colonisation. This method can be variously applied for studying behaviour of dispersed lichen spores.
|Bidragets oversatte titel
|Spore spiring in vitro i lavarten Xanthoria parietina under indflydelse af bark ekstrakt
|Udgivet - 27 mar. 2021