Short-term responses of primary processes in PS II to low temperature are sensitively indicated by fast chlorophyll fluorescence kinetics in Antarctic lichen Dermatocarpon polyphyllizum

Abstract

In this study, we investigated the effects of low temperature on the fast chlorophyll fluorescence transient (OJIP) and OJIP-derived parameters in chlorolichen Dermatocarpon polyphyllizum expossed to a gradually decreasing temperature (22°C, 18°C, 14°C, 12°C, 10°C, 7°C and 4°C). The segments of lichen thalli were exposed to a certain temperature either in dark-and light-adapted state for 10 minutes in order to evaluate the effects on chlorophyll fluorescence parameters. The initial photochemical phase of the transient (O-J) due to reduction of the primary quinone acceptor (Q A) was found temperature dependent. The K-step was apparent for the samples measured at the temperature above 12°C, but not below 10 o C in light-adapted lichen thalli. With the thallus temperature decrease, majority of the chlorophyll fluorescence parameters derived from OJIP (ET 0 /RC, Psi_0, and DI 0 /RC) showed no change in light-adapted samples but a decrease in darkadapted samples. The effects of dark-/ light-adaptation of the lichen samples on the OJIP and OJIP-derived parameters was attributed to the differences in production/utilization of high-energy products of primary photochemical processes of photosynthesis in darkand light-adapted state, respectively. The other parameters (ABS/RC, TR 0 /RC) showed a decrease with thallus temperature decrease both in light-and dark-adapted samples. The results suggest that fast chlorophyll fluorescence trasient is an useful tool to investigate temperature-dependent changes in photosystem II in chlorolichens, their photobionts, respectively.

Limitation of photosynthetic processes in photosystem II in alpine mosses exposed to low temperatures: Response of chlorophyll fluorescence parameters

“…The L-step, that reflects changes in the connectivity between LHCs and RC, was visualized in both species at -10°C; however, S. girgensohnii also reflected it at the temperature of -1°C. These results are comparable to the K-and L-step found in Antarctic lichen treated by subzero temperature (Marečková et Barták 2017, Marečková et al 2018.…”

“…For visualisation of the K-step the data was double normalized between F 0 and F J (2 ms), expressed as W OJ = (F t -F 0 )/(F J -F 0 ), this enables visualisation at around 240-300 µs (Marečková et al 2017). F J values were directly taken from the OJIP curves because the exact time of the J-step usually varies with stress.…”

Combined chlorophyll fluorescence techniques to study environmental impact on the mountain moss Polytrichum commune

“…Such response was described in poikilohydric autotrophs for other stressors such as e.g. high temperature (Marečková and Barták 2017). In the same way TR 0 /RC and ET 0 /RC (related to energy flux per RC, respectively leading to Q A reduction, and photosynthetic linear electron transpor), increased at the final stages of desiccation, to cope with the excess of absorbed light to be transferred and conveyed on a smaller number of RCs than in hydrated state.…”

Special issue in honour of Prof. Reto J. Strasser - Analysis of K- and L-band appearance in OJIPs in Antarctic lichens in low and high temperature

“…From the OJIP curves, ChlF parameters were derived as follows: ABS/RC is the absorption flux per RC, TR0/RC is the trapped energy flux per RC, ET0/RC is the electron transport flux per RC, and DI0/RC is the flux of dissipated excitation energy, all for dark-adapted state, and PIABS (the so-called performance index) is the potential for energy conservation from exciton to the reduction of plastoquinone pool, whereas PIABStotal is the potential for energy conservation from exciton to the reduction of final acceptors of PSI (for reviews see Strasser et al 2004, Stirbet et al 2018. For visualisation of K-band, the data of ChlF transients were double normalised between F0 and FJ (2 ms), expressed as WOJ = (Ft -F0)/(FJ -F0) (Tsimilli-Michael and Strasser 2008, Marečková et al 2017. For the L-band analysis, the data were double normalised as WOK = (Ft -F0)/(FK -F0), where FK represents the ChlF value at 0.3 ms. For L-and K-bands, the data used were the difference between the temperature-stressed samples and control lichens measured at +20°C.…”