Effects of UVC254 nm on the photosynthetic activity of photobionts from the astrobiologically relevant lichens Buellia frigida and Circinaria gyrosa. Issue 4 (6th October 2014)

• Record Type: Journal Article
• Authors: Meeßen, J.; Backhaus, T.; Sadowsky, A.; Mrkalj, M.; Sánchez, F.J.; de la Torre, R.; Ott, S.
• Is Part Of: International journal of astrobiology. Volume 13:Issue 4(2014:Oct.)
• Page Start: 340
• Page End: 352
• Publication Date: 2014-10-06
• Subjects: astrobiology, -- BIOMEX, -- extremotolerance, -- lichens, -- photobionts, -- photodamage, -- UVC; Exobiology -- Periodicals; 576.83905
• DOI: 10.1017/S1473550414000275
• Languages: English
• ISSNs: 1473-5504

Abstract

Abstract: In the past decade, various astrobiological studies on different lichen species investigated the impairment of viability and photosynthetic activity by exposure to simulated or real space parameters (as vacuum, polychromatic ultraviolet (UV)-radiation and monochromatic UVC) and consistently found high post-exposure viability as well as low rates of photosynthetic impairment (de Vera et al. 2003, 2004a; 2004b; de la Torre et al. 2010; Onofri et al . 2012; Sánchez et al. 2012, 2014; Brandt et al . 2014). To achieve a better understanding of the basic mechanisms of resistance, the present study subdued isolated and metabolically active photobionts of two astrobiologically relevant lichens to UVC254 nm, examined its effect on photosynthetic activity by chlorophyll a fluorescence and characterized the UVC-induced damages by quantum yield reduction and measurements of non-photochemical quenching. The results indicate a strong impairment of photosynthetic activity, photoprotective mechanisms and overall photobiont vitality when being irradiated in the isolated and metabolically active state. In conclusion, the present study stresses the higher susceptibility of photobionts towards extreme environmental conditions as UVC-exposure, a stressor that does not occur on the Earth. By comparison with previous studies, the present results highlight the importance of protective mechanisms in lichens, such as morphological–anatomical traits (Meeßen et al . 2013), secondary lichen compounds (Meeßen et al . 2014) and the symbiont's pivotal ability to pass into anhydrobiosis when desiccating.