Survival of Xanthoria parietina in simulated space conditions: vitality assessment and spectroscopic analysis

Xanthoria parietina is awidespread foliose lichen growing on barks and rocks showing a broad spectrumof tolerance to air pollutants such as NOX and heavymetals, and resistance to UV-radiation because of the screening properties provided by the secondary metabolite parietin. The aim of this study was to evaluate the ability of this lichen species to survive in the following simulated space conditions, UV-radiation in N-2 atmosphere and UV-radiation in vacuum. The efficiency of the photosynthetic apparatus was used as an indicator of vitality, and was expressed in terms of chlorophyll a fluorescence (FV/FM) and Normalized DifferenceVegetation Index (NDVI), whichweremeasuredwithin 72 h fromthe exposure. Additionally, during the irradiation, the IR reflectance spectrum of the lichen was monitored in situ to assess changes in spectral bands. The results showed significant differences in physiological recovery trends between the treatments, highlighting that UV-radiation in vacuum causes stronger effects on FV/FM values. The IR analysis revealed several spectral band changes in the fingerprint region. The most visible variation was the 5200 cm(-1) water band that disappeared in the overtone region. Nevertheless, X. parietina was able to survive UV-radiation in N-2 atmosphere and in vacuum, and for this reason it may be considered a candidate for further evaluations on its survival capacity in extreme conditions.

Automated summary

This study evaluated the survival ability of Xanthoria parietina lichen under simulated space conditions. The results showed that it was able to survive in N-2 atmosphere and vacuum, and exhibited a certain level of physiological recovery.