Photobiont Selectivity and Interspecific Interactions in Lichen Communities. I. Culture Experiments with the Mycobiont Fulgensia bracteata

Abstract: Lichen communities are characterised by interspecific interactions that not only include interactions between different lichen species but also between the symbionts within a single lichen species. The community “Bunte Erdflechtengesellschaft”, growing on weathered calciferous rocks known as Gravel Alvar on Gotland (Baltic Sea, Sweden), shows a high complexity of inter‐ and intraspecific interactions, including Fulgensia bracteata, F. fulgens, Toninia sedifolia, Squamarina cartilaginea, Psora decipiens and Lecidea lurida. F. bracteata and F. fulgens are the dominant species of this community, showing a tendency to overgrow the other species involved and even parasitic behaviour. Culture experiments have been performed to investigate the selectivity of the mycobiont of F. bracteata towards a variety of potential photobionts. The results provide evidence for the selectivity of the mycobiont and varying compatibility of the respective symbionts that can be interpreted as a cascade of interdependent processes of specific and non‐specific reactions of the symbionts involved.     

Three isocoumarins and a benzofuran from the cultured lichen mycobionts of Pyrenula sp

The spore-derived mycobionts of the lichen Pyrenula sp. were cultivated on a malt-yeast extract medium supplemented with 10% sucrose. The investigation of their metabolites resulted in isolation of four compounds, three isocoumarins and a biogenetically related benzofuran; their structures were determined by spectroscopic methods.