caa a22 4500 606208488 CHVBK 20210128101022.0 cr unu---uuuuu 210128e20150801xx s 000 0 eng 10.1007/s00425-015-2319-z doi (NATIONALLICENCE)springer-10.1007/s00425-015-2319-z Desiccation tolerance and lichenization: a case study with the aeroterrestrial microalga Trebouxia sp. (Chlorophyta) [Elektronische Daten] [Fabio Candotto Carniel, Davide Zanelli, Stefano Bertuzzi, Mauro Tretiach] Main conclusions : A comparative study of isolated vs. lichenized Trebouxia sp. showed that lichenization does not influence the survival capability of the alga to the photo-oxidative stress derived from prolonged desiccation. Coccoid algae in the Trebouxia genus are the most common photobionts of chlorolichens but are only sporadically found in soil or bark outside of a lichen. They all appear to be desiccation tolerant, i.e. they can survive drying to water contents of below 10%. However, little is known about their longevity in the dry state and to which extent lichenization can influence it. Here, we studied the longevity in the dry state of the lichenized alga (LT) Trebouxia sp. in the lichen Parmotrema perlatum, in comparison with axenically grown cultures (CT) isolated from the same lichen. We report on chlorophyll fluorescence emission and reactive oxygen species (ROS) production before desiccation, after 15-45days in the dry state under different combinations of light and air humidity and after recovery for 1 or 3days in fully hydrated conditions. Both the CT and the LT were able to withstand desiccation under high light (120µmol photons m−2s−1 for 14h per day), but upon recovery after 45days in the dry state the performance of the CT was better than that of the LT. By contrast, the quenching of excess light energy was more efficient in the LT, at high relative humidities especially. ROS production in the LT was influenced mostly by light exposure, whereas the CT showed an oxidative burst independent of the light conditions. Although lichenization provides benefits that are essential for the survival of the photobiont in high-light habitats, Trebouxia sp. can withstand protracted periods of photo-oxidative stress even outside of a lichen thallus. Springer-Verlag Berlin Heidelberg, 2015 Chlorophyll fluorescence nationallicence Parmotrema perlatum nationallicence Photo-oxidation nationallicence ROS nationallicence Symbiosis nationallicence Chl a F : Chlorophyll a fluorescence nationallicence CLSM : Confocal laser scanning microscopy nationallicence CT : Cultured Trebouxia nationallicence DCF : 2′,7′-Dichlorofluorescein nationallicence DCFH : 2′,7′-Dichlorofluorescin nationallicence DCFH-DA : 2′,7′-Dichlorofluorescin diacetate nationallicence F 0 and F m : Minimal and maximal Chl fluorescence intensity in dark-adapted samples, respectively nationallicence F′ m : Maximum quantum yield of photosystem II in illuminated samples nationallicence F p : Maximal Chl fluorescence under non-saturating actinic light nationallicence F v : Variable Chl fluorescence (F v=F m−F 0) nationallicence F v/ F m : Maximum quantum yield of photosystem II nationallicence LT : Lichenized Trebouxia nationallicence NPQ : Non photochemical quenching nationallicence PPFDIk : Photosynthetic photon flux density corresponding to the effective maximum value of quantum yield CO2 assimilation nationallicence RH : Air relative humidity nationallicence ROS : Reactive oxygen species nationallicence RWC : Relative water content nationallicence Candotto Carniel Fabio Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut Zanelli Davide Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut Bertuzzi Stefano Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut Tretiach Mauro Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut Planta Springer Berlin Heidelberg 242/2(2015-08-01), 493-505 0032-0935 242:2<493 2015 242 425 https://doi.org/10.1007/s00425-015-2319-z text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00425-015-2319-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Candotto Carniel Fabio Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut NATIONALLICENCE 700 1- Zanelli Davide Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut NATIONALLICENCE 700 1- Bertuzzi Stefano Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut NATIONALLICENCE 700 1- Tretiach Mauro Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via L. Giorgieri, 10, 34127, Trieste, Italy aut NATIONALLICENCE 773 0- Planta Springer Berlin Heidelberg 242/2(2015-08-01), 493-505 0032-0935 242:2<493 2015 242 425