Changes in photosynthesis, pigment composition and glutathione contents in two Antarctic lichens during a light stress and recovery

Abstract

Over last decades, several studies have been focused on short-term high light stress in lichens under laboratory conditions. Such studies reported a strong photoinhibition of photosynthesis accompanied by a partial photodestruction of PSII, involvement of photoprotective mechanisms, and resynthetic processes into gradual recovery. In our paper, we applied medium [800 µmol(photon) m -2 s -1 ] light stress to induce negative changes in PSII funcioning as well as pigment and glutathione (GSH) content in two Antarctic fruticose lichen species. Chlorophyll (Chl) fluorescence parameters, such as potential and effective quantum yield of photosynthetic processes and fast transients (OJIP) recorded during high light exposition and recovery, revealed that Usnea antarctica was less susceptible to photoinhibition than U. aurantiaco-atra. This might be supported by a more pronounced high light-induced reduction in Chl a and b contents in U. aurantiaco-atra compared with U. antarctica. In both experimental species, total GSH showed an initial increase during the first 30-40 min of high light treatment followed by a decrease (60 min) and an increase during dark recovery. Full GSH recovery, however, was not finished in U. aurantiaco-atra even after 5 h indicating lower capacity of photoprotective mechanisms in the species. OJIP curves showed high light-induced decrease in both species, however, the recovery of the OJIPs shape to pre-photoinhibitory values was faster and more apparent in U. antarctica than in U. aurantiaco-atra. The results are discussed in terms of sensitivity of the two species to photoinhibition and their photosynthetic performance in natural environment.

Glutathione (GSH) Production as Protective Adaptation Against Light Regime Radiation of Symbiodinium Natural Population

“…Although the relative depletion effect of both treatments considerable has the same value. The dynamic of intracellular GSH concentration of Symbiodinium biomass may therefore be expected to play important roles for the cell with regard to the metabolic functions (Balarinova et al, 2014). The phenomena may correlated also with the lightdependence (photorespiration) of GSH accumulation in Symbiodinium cells.…”

“…With increasing stress, cell metabolism severely disrupted. When membranes and cell compartments are destroyed, the chain reactions of photorespiratory occur at membrane lipids and proteins, and can further destroy cellular organization (Balarinova et al, 2014). In the course of such destructive reaction the formation of free radicals is augmented in all cellular compartments.…”

Comparative analysis of heterogeneity of primary photosynthe-tic processes within fruticose lichen thalli: Preliminary study of interspecific differences ( Short Communication )

“…Barták et al 2000), whose planar thalli are relatively easy to handle but little research has investigated the spatial heterogeneity within the thallus of fruticose lichens. A recent study (Balarinová et al 2014) reported interspecific differences in distribution of photosynthetic activity within the thalli of two Antarctic species of Usnea, as well as different sensitivities to photoinhibition. In this study, primary photosynthetic processes were found to be more efficient in the basal and middle part of branching thalli (yellow colored) while very low values were detected in the apical (dark colored) parts.…”

Spatial organization of the three‐component lichen Peltigera aphthosa in functional terms

“…They are characterized by a high tolerance to adverse conditions (desiccation, low temperature, UV-radiation etc.) (Jensen et al 1999, De Vera et al 2002, Balarinová et al 2014, Barták et al 2015 and ability to synthesize diverse value-added compounds (antibiotics, antioxidants, photoprotectors and regulators of microalgal growth) (Stocker-Wörgötter 2001, Molnár and Farkas 2010). To elucidate the mechanisms of stress tolerance in lichens and to assess biotechnological potential of the lichen components, Abbreviations -CF, chlorophyll a fluorescence; ETC, electron transport chain; Fm ′ , maximal CF intensity in light-adapted state; Fo, minimal CF intensity in dark-adapted state; Fv/Fm, maximal PSII photochemical quantum yield of dark-adapted state; N(Q A ), Q A turnover number; NPQ, non-photochemical quenching; OJIP, CF transient curve; p25th, 25th percentile; p75th, 75th percentile; PAR, photosynthetic active radiation; PSII, photosystem II; Q A , primary PSII quinone acceptor; SHA, specific hemagglutination activity.…”