Photoinhibition and recovery of primary photosynthesis in Antarctic and subantarctic lichens. Analysis of interspecific differences

This study meticulously investigates the dynamics of photoinhibition and the mechanisms of primary photosynthetic activity recovery in lichens found in Antarctica and the sub-Antarctic regions. Advanced methodologies were utilised, such as Kautsky's kinetic analysis and the OJIP test. The study carefully details the response of various lichen species to intense light stress, outlining both immediate effects and subsequent recovery processes. Our findings reveal that these lichens employ a range of adaptive strategies, specific to each species, to mitigate the effects of photoinhibition, thereby emphasizing their remarkable resilience and ecological importance in harsh environments. Notably, the investigation reveals the sophisticated interplay between inherent photoprotective mechanisms and the ecological adaptations that enable these lichens to thrive under such harsh conditions. The study not only advances our knowledge of plant physiology under stress but also enriches our insights into the survival strategies of terrestrial organisms facing global environmental changes. Three types of photoinhibitory treatments differing in their duration and strength were applied to 7 lichen species from Antarctica and South America (Isla Navarino). The lichens responded with a decrease in photosynthetic processes in photosystem II (FV/FM and ΦPSII declined), although they showed almost complete recovery in the following 5 h. This was attributed to the activation of photoprotective mechanisms, non-photochemical quenching (NPQ) in particular, during photoinhibitory treatments. Chlorophyll fluorescence parameters derived from slow Kautsky kinetics were correlated with those derived from the OJIP curve. Our study presents data that supports the conclusion of significant photoresistance of the studied lichen species in the hydrated state to photoinhibition induced by high doses of photosynthetically active radiation (PAR).