Lichen photobionts show tolerance against lichen acids produced by lichen mycobionts.

In order to determine the allelopathic nature of lichen acids produced by lichen mycobionts, we compared lichen photobionts with other photosynthetic organisms in terms of inhibition of photosynthetic electron transport around photosystem II (PSII) by representative lichen acids. Whereas at the thylakoid level we found no clear difference in tolerance against lichen acids between lichen photobionts and other species, at the cellular level lichen photobionts showed strong tolerance as compared with other species. These findings suggest the presence of a lichen acid-specific exclusion or detoxification mechanism in lichen photobiont cells.