CZECH POLAR REPORTS 8 (2): 286-298, 2018 Comparative research of photosynthetic processes in selected poikilohydric organisms from Mediterranean and Central- European alpine habitats Gabriella Nora Maria Giudici1, Josef Hájek2, Miloš Barták2, Svatava Kubešová3,4 1University of Naples Federico II, Department of Agriculture, 80055 Portici, Italy 2Masaryk University, Faculty of Science, Department of Experimental Biology, Labora- tory of Photosynthetic Processes, Kamenice 5, Building A13, 625 00 Brno, Czech Republic 3Masaryk University, Faculty of Science, Department of Botany and Zoology, Kamenice 5, 625 00 Brno, Czech Republic 4Moravian Museum, Department of Botany, Hviezdoslavova 29a, 627 00, Brno, Czech Republic Abstract Dehydration-induced decrease in photosynthetic activity was investigated in five poikilohydric autotrophs using chlorophyll fluorescence parameters recorded during controlled desiccation. For the study, two representatives of mosses from alpine zone (Rhizomnium punctatum, Rhytidiadelphus squarrosus) of the Jeseníky Mts. (Czech Republic) were used. Other two experimental species were mediterranean habitats liverwort (Pellia endiviifolia) and moss (Palustriella commutata), collected from under Woodwardia radicans canopy in the Nature Reserve Valle delle Ferriere (Italy). The last species was a liverwort (Marchantia polymorpha) collected from lowland site (Brno, Moravia, Czech Republic). We investigated the relationship between relative water con- tent (RWC) and several chlorophyll fluorescence parameters evaluating primary photo- chemical processes of photosynthesis, such as effective quantum yield of photosynthetic processes in photosystem II (ΦPSII), and non-photochemical quenching (qN). With desiccation from fully wet (RWC = 100%) to dry state (RWC = 0%), ΦPSII exhibited a rapid (R. punctatum) and slow decline of ΦPSII (R. squarrosus, P. endiviifolia, M. polymorpha, and P. commutata). Shapes of dehydration-response curves were spe- cies-specific. RWC0.5, i.e. the RWC at which the sample showed half of maximum ΦPSII, reflected the species-specificity. It reached 65% in desiccation sensitive (R. punctatum), 53% and 43% in semi-tolerant (P. commutata and R. squarrosus), 24% and 18% in desiccation-tolerant species (P. endiviifolia and M. polymorpha). In all experimental species, non-photochemical quenching (qN) of absorbed light energy showed high values at RWC = 100% and a slight increase with desiccation. Steady state chlorophyll fluorescence (FS) remained high during desiccation and was not correlated with ΦPSII. DOI: 10.5817/CPR2018-2-24 ——— Received November 6, 2018, accepted December 22, 2018. *Corresponding author: G. N. M. Giudici <[email protected]> Acknowledgements: The authors thank the projects CzechPolar-II (LM2015078) for providing Brno-based facilities and the infrastructure for the research reported in this study. The authors thank also for the support from ECOPOLARIS project (CZ.02.1.01/0.0/0.0/16_013/0001708) aimed to fund the research reported in this paper and Carabinieri per la biodiversità, UTB Caserta, for field support in collecting samples from Woodwardia radicans restricted area. The help of the members of the Extreme Environments Life (EEL) laboratory (Masaryk University, Department of Experimental Biology, Brno) provided during data processing is also acknowledged. 286 G. N. M. GIUDICI et al. Key words: chlorophyll fluorescence, moss, liverwort, dehydration, photosynthesis, Woodwardia radicans Introduction Mosses and liverworts, being desicca- ciated with an increase in thermotolerance, tion tolerant poikilohydric autotrophs, cope i.e. increase of thermal stability of chloro- well with dehydration/rehydration cycles plastic photosynthetic apparatus, as shown and are capable to restore their photosyn- for Homalothecium lutescens by Dulai et thetic activity soon after being rehydrated al. (2004). Recently, the phenomenon of (Proctor et Smirnoff 2000). There are sev- inducible desiccation tolerance is studied eral ecophysiological adaptations, mainly in mosses. Generally, majority of mosses protective mechanisms (see e.g. Green- are considered desiccation-tolerant, while wood 2017, for review), helping such or- e.g. Marchantia polymorpha (liverwort) be- ganisms to inhibit and recover their photo- longs to desiccation sensitive species (Na- synthetic activities during desiccation and be et al. 2007). Also Pellia endiviifolia is rehydration, respectively. Most moss spe- considered desiccation-intolerant liverwort cies are highly resistant to desiccation. The species (Deltoro et al. 1998b). Since the process of drying and rehydration can be 90-ies (e.g. Deltoro et al. 1998a, Csintalan repeated several times without causing et al. 1999) of the last century, chlorophyll major changes in the functioning of the fluorescence technique has been extensive- organism (Stoklasa-Wojtasz et al. 2012). ly used for the evaluation of dehydration According to their capabilities to restore effects on moss and liverwort photosyn- physiological characteristics after repeated thesis. The approach was applied also in cycles of hydration-dehydration, moss spe- other poikilohydric organisms, such as e.g. cies are divided into two categories: desic- Nostoc commune colonies (Barták et al. cation tolerant or desiccation sensitive. 2016). Typically, the photosynthetic stud- This concept, however, is considered not ies of such autotrophs at different degrees generally valid recently since there are of dehydration combine gas exchange and many interacting factors, such as e.g. phe- chlorophyll fluorescence measurements (e.g. notypic (Proctor et al. 2007) end ecotypic Hu et al. 2016). Several previous studies plasticity of the species, physiological ´his- (e.g. Heber et al. 2001, Pressel et al. 2006) tory´ of the sample, microclimate effects, have shown that chlorophyll fluorescence the effects of the rate of desiccation/de- is almost totally suppressed during de- hydration that may co-act and change the hydration in bryophytes. Therefore, the desiccation tolerance/sensitivity. Although change in chlorophyll fluorescence emis- many of protective mechanisms of bryo- sion and chlorophyll fluorescence parame- phytes are common with the higher plants, ters is a very useful tool in the evalua- there are fundamental interspecific differ- tion of negative effects of dehydration on ences in their response to desiccation. moss/liverwort photosynthesis. It has been Study of Marschall et al. (2018) reported shown by e.g. Hájek et Beckett (2008) that desiccation-tolerant (Porella platyphylla) critical relative water content (RWC) and/ and desiccation-sensitive (Sphagnum angus- or water potential of a moss thallus might tifolium) mosses. In slowly desiccating be evaluated by chlorophyll fluorescence mosses, desiccation tolerance may increase technique, the potential (FV/FM) and effec- thanks to the involvement of ABA (May- tive quantum yield (ΦPSII). aba et al. 2001, Wise et Tunnacliffe 2004). In this comparative study, we focused Early stages of moss desiccation are asso- on the changes in primary photosynthetic 287 PHOTOSYNTHESIS IN RESPONSE TO DESICCATION processes monitored by chlorophyll fluo- at which a half of the maximum ΦPSII is rescence parameters during desiccation in found. The emphasis was also given to the five poikilohydric autotrophs. We expected critical RWC, i.e. relative water content at species-specific responses in gradually des- which the individual species show full lim- iccating samples, among these the water itation of primary photochemical processes content at which the first signs of inhibi- of photosynthesis. tion of photosynthesis appear and the RWC Material and Methods Sampling sites Samples of Rhizomnium punctatum and Samples of Pellia endiviifolia and Pa- Rhytidiadelphus squarrosus were collected lustriella commutata were collected in the from the Jeseniky Mts. (NE of the Czech Valle delle Ferriere (Italy), 33 km SE of Republic, Moravian-Silesian region). The Naples and 17 km west of Salerno. The samples of R. punctatum were collected locality is a deep valley rich in water and from the ground close to the margin of a waterfalls, with a permanent stream at its stream with dominant grass cover close to bottom (Canneto). The area is located in the Barborka chalet (1 320 m a.s.l.). Sam- the southern side of the Sorrento penin- ples of R. squarrosus were collected from sula, made by Mesozoic limestone, trans- the locality called the Kapitánská stezka gressive Miocene calcarenite and flysch, (940 m a.s.l.). The samples were collected with occurrences of volcanic deposits from from the moss-dominated vegetation cover- Somma-Vesuvius. The main valley is ing a ground within a mature Norway crossed by secondary valleys and the un- spruce (Picea abies L.) stand (the Jeseníky derground faults along with the karst sys- Mts., Czech Republic). The climate of the tem regulate the water flow and drainage, Jeseníky Mts. is characterized by annual generating many springs. It is surrounded mean temperature of 1.1°C (from meteoro- by mountains and peaks, the altitude of logical station Praděd, 1 492 m a.s.l., Led- which ranges from 300 to 1 203 m a.s.l. nický 1985). The coldest month is January The climate is warm temperate (20°C to with the monthly mean of -7.5°C. The 5°C). The average annual rainfall of 1 500 warmest one is July (9.7°C). Annual sum (mountain) to 1 000 (sea level) mm, hits of precipitation reaches 1 231 mm with its maximum in the autumn - winter period. monthly maximum found