Abstract
Main conclusion
During desiccation, both apparent electron transport rate (ETRapp) and photosynthetic CO2 uptake peak when external water has evaporated. External water, causing suprasaturation, weakens the strong correlation between ETRapp and CO2 uptake.
Abstract
Lichens are poikilohydric organisms passively regulated by ambient conditions. In theory, apparent electron transport rate (ETRapp), estimated by photosystem II yield measured in light (ΦPSII), is a proxy of photosynthetic CO2 uptake. Hydration level, however, is a complicating factor, particularly during suprasaturation that strongly reduces CO2 diffusion. Here, the cephalolichen Lobaria pulmonaria and two chlorolichens Parmelia sulcata and Xanthoria aureola were excessively hydrated before photosynthetic CO2 uptake and ΦPSII using imaging fluorescence tools were simultaneously measured while drying at 200 µmol photons m−2 s−1. CO2 uptake peaked when hydration had declined to a level equivalent to their respective internal water holding capacity (WHCinternal) i.e., the water per thallus area after blotting external water. CO2 uptake and ETRapp in all species were highly correlated at hydration levels below WHCinternal, but weaker at higher hydration (chlorolichens) or absent (cephalolichen). Yet, at a specimen level for the two chlorolichens, the correlation was strong during suprasaturation. The CO2 uptake—ETRapp relationship did not differ between measured species, but may vary between other lichens because the slope depends on cortical transmittance and fraction of electrons not used for CO2 uptake. For new lichen species, calibration of ETRapp against CO2 uptake is therefore necessary. At intrathalline scales, ΦPSII during drying initially increased along thallus margins before reaching maximum values in central portions when hydration approached WHCinternal. WHCinternal represents the optimal hydration level for lichen photosynthesis. In conclusion, ETRapp is an easily measured and reliable proxy of CO2 uptake in thalli without external water but overestimates photosynthesis during suprasaturation.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Abbreviations
- ETRapp :
-
Apparent electron transport rate
- ETR:
-
Electron transport rate
- Amax :
-
Maximum CO2 uptake, µmol CO2 m−2 s−1
- ΦPSII :
-
Photosystem II quantum yield in light
- STM:
-
Specific thallus mass, mg DM cm−2
- WHCinternal :
-
Water holding capacity after gentle blotting with drying paper, mg H2O cm−2
- WHCtotal :
-
Water holding capacity after gentle shaking, mg H2O cm−2
- WHCexternal :
-
WHCtotal−WHCinternal, mg H2O cm−2
- WCinternal :
-
Water content after gentle blotting with drying paper, percent
References
Baker NR (2008) Chlorophyll fluorescence: A probe of photosynthesis in vivo. Annu RevPlant Biol 59:89–113. https://doi.org/10.1146/annurev.arplant.59.032607.092759
Barták M, Solhaug KA, Vrábliková H, Gauslaa Y (2006) Curling during desiccation protects the foliose lichen Lobaria pulmonaria against photoinhibition. Oecologia 149:553–560
Bates D, Maechler M, Bolker B, Walker S (2015) Fitting linear mixed-effects models using lme4. J Stat Softw 67:1–48. https://doi.org/10.18637/jss.v067.i01
Ellis CJ (2016) Oceanic and temperate rainforest climates and their epiphyte indicators in Britain. Ecol Ind 70:125–133. https://doi.org/10.1016/j.ecolind.2016.06.002
Foyer CH, Bloom AJ, Queval G, Noctor G (2009) Photorespiratory metabolism: genes, mutants, energetics and redox signalling. Annu Rev Plant Biol 60:455–484
Gauslaa Y, Solhaug KA (1998) The significance of thallus size for the water economy of the cyanobacterial old-forest lichen Degelia plumbea. Oecologia 116:76–84
Gauslaa Y, Solhaug KA (2001) Fungal melanins as a sun screen for symbiotic green algae in the lichen Lobaria pulmonaria. Oecologia 126:462–471
Gauslaa Y, Solhaug KA, Longinotti S (2017) Functional traits prolonging photosynthetically active periods in epiphytic cephalolichens during desiccation. Environ Exp Bot 141:83–91. https://doi.org/10.1016/j.envexpbot.2017.07.005
Green TGA, Schroeter B, Kappen L, Seppelt RD, Maseyk K (1998) An assessment of the relationship between chlorophyl a fluorescence and CO2 gas exchange from field measurements on a moss and lichen. Planta 206:611–618
Harrison XA, Donaldson L, Correa-Cano ME, Evans J, Fisher DN, Goodwin CED, Inger R (2018) A brief introduction to mixed effects modelling and multi-model inference in ecology. PeerJ 6:e4794. https://doi.org/10.7717/peerj.4794
Honegger R (1991) Functional aspects of lichen symbiosis. Annu Rev Plant Physiol Plant Mol Biol 42:553–578
Honegger R (1998) The lichen symbiosis - What is so spectacular about it? Lichenologist 30:193–212
Johnson PCD (2014) Extension of Nakagawa & Schielzeth’s (R2GLMM) to random slopes models. Methods Ecol Evol 5:944–946. https://doi.org/10.1111/2041-210x.12225
Lange OL (2003) Photosynthetic productivity of the epilithic lichen Lecanora muralis: long-term field monitoring of CO2 exchange and its physiological interpretation II. Diel and seasonal patterns of net photosynthesis and respiration. Flora 198:55–70. https://doi.org/10.1016/s0367-2530(04)70052-3
Lange OL, Green TGA (2006) Nocturnal respiration of lichens in their natural habitat is not affected by preceding diurnal net photosynthesis. Oecologia 148:396–404
Lange OL, Büdel B, Heber U, Meyer A, Zellner H, Green TGA (1993a) Temperate rainforest lichens in New Zealand: high thallus water content can severely limit photosynthetic CO2 exchange. Oecologia 95:303–313
Lange OL, Büdel B, Meyer A, Kilian E (1993b) Further evidence that activation of net photosynthesis by dry cyanobacterial lichens requires liquid water. Lichenologist 25:175–189
Lange OL, Green TGA, Reichenberger H, Hesbacher S, Proksch P (1997) Do secondary substances in the thallus of a lichen promote CO2 diffusion and prevent depression of net photosynthesis at high water content? Oecologia 112:1–3
Lange OL, Green TGA, Heber U (2001) Hydration-dependent photosynthetic production of lichens: what do laboratory studies tell us about field performance? J Exp Bot 52:2033–2042
Leisner JMR, Green TGA, Lange OL (1997) Photobiont activity of a temperate crustose lichen: long-term chlorophyll fluorescence and CO2 exchange measurements in the field. Symbiosis 23:165–182
Lüdecke D (2018) ggeffects: tidy data frames of marginal effects from regression models. J Open Source Softw 3:772. https://doi.org/10.21105/joss.00772
Nakagawa S, Schielzeth H (2013) A general and simple method for obtaining R2 from generalized linear mixed-effects models. Methods Ecol Evol 4:133–142. https://doi.org/10.1111/j.2041-210x.2012.00261.x
Phinney NH, Solhaug KA, Gauslaa Y (2018) Rapid resurrection of chlorolichens in humid air: specific thallus mass drives rehydration and reactivation kinetics. Environ Exp Bot 148:184–191. https://doi.org/10.1016/j.envexpbot.2018.01.009
Phinney NH, Gauslaa Y, Solhaug KA (2019a) Why chartreuse? The pigment vulpinic acid screens blue light in the lichen Letharia vulpina. Planta 249:709–718. https://doi.org/10.1007/s00425-018-3034-3
Phinney NH, Solhaug KA, Gauslaa Y (2019b) Photobiont-dependent humidity threshold for chlorolichen photosystem II activation. Planta 250:2023–2031. https://doi.org/10.1007/s00425-019-03282-4
Solhaug KA (2018) Low-light recovery effects on assessment of photoinhibition with chlorophyll fluorescence in lichens. Lichenologist 50:139–145. https://doi.org/10.1017/s0024282917000640
Solhaug KA, Gauslaa Y (1996) Parietin, a photoprotective secondary product of the lichen Xanthoria parietina. Oecologia 108:412–418
Solhaug KA, Larsson P, Gauslaa Y (2010) Light screening in lichen cortices can be quantified by chlorophyll fluorescence techniques for both reflecting and absorbing pigments. Planta 231:1003–1011
Author information
Authors and Affiliations
Corresponding author
Additional information
Communicated by Dorothea Bartels.
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Solhaug, K.A., Asplund, J. & Gauslaa, Y. Apparent electron transport rate – a non-invasive proxy of photosynthetic CO2 uptake in lichens. Planta 253, 14 (2021). https://doi.org/10.1007/s00425-020-03525-9
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00425-020-03525-9