A possible role of carotenoids in green alga and Cyanobacteria adaptation to the lichen symbiosis conditions

摘要

The carotenoids of photobionts from two species of lichen genus Peltigera was investigated. No difference in carotenoid composition between symbiotic and free living green alga and cyanobacteria was found. Changes in photobiont pigment contents under the oxidative stress were studied using a model system (FeSO_4-ascorbate) producing active oxygen species. FeSO_4-ascorbate increased zeaxanthin amount in the symbiotic green algae Coccomyxa sp. and gave rise to zeaxanthin and canthaxanthin accumulation in the symbiotic cyanobacterium Nostoc sp. The additional synthesis of antioxidative active carotenoids seems to be one of the adaptive reactions of photobiont to interaction with parasitic fungus occuring in lichen association.