Vegetation mapping of moss-dominated areas of northern part of James Ross Island (Antarctica) and a suggestion of protective measures

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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.

Section: Sample Collection and Handlingmentioning

confidence: 99%

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

Marečková¹,

Barták²

2017

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“…They were collected in two different regions neighbouring to the Antarctic peninsula. P. muscigena was collected at the James Ross Island from a long-term research plot (63° 48´ 03´´ S, 57° 52´ 50´´ W, see Barták et al 2015 for details) located close to Mendel (Czech Antarctic research station). Umbilicaria antarctica was collected in the Maritime Antarctic at the Galindez Island in a close vicinity of Ukrainian station Vernadsky (65° 14´ 43´´ S, 64° 15´ 24´´ W).…”

Section: Sample Collecting and Handlingmentioning

confidence: 99%

Effects of short-term low temperature stress on chlorophyll fluorescence transients in Antarctic lichen species

Marečková¹,

Barták²

2016

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Chlorophyll fluorescence is an effective tool for investigating characteristics of any photosynthesizing organisms and its responses due to different stressors. Here, we have studied a short-term temperature response on two Antarctic green algal lichen species: Umbilicaria antarctica, and Physconia muscigena. We measured slow chlorophyll fluorescence transients in the species during slow a cooling of thallus temperature from 20°C to 5°C with a 10 min. acclimation at each temperature in dark. The measurements were supplemented with saturation pulses for the analysis of chlorophyll fluorescence parameters: maximum yield of PS II photochemistry (FV/FM), effective quantum yield of PS II photochemistry (FPSII) and non-photochemical quenching (NPQ). In response to decreasing thallus temperature, we observed species-specific changes in chlorophyll fluorescence levels P, S, M, T reached during chlorophyll fluorescence transient as well as in the shape of the chlorophyll fluorescence transients. With a decrease in temperature, the time at which M and T chlorophyll fluorescence levels were reached, increased. These changes were attributed to redox state of plastoquinon pool, changes in Calvin-Benson cycle activity, non-photochemical quenching components, state transition in particular. In this study, we present some chlorophyll fluorescence ratios (P/M, M/T, P/T) and chlorophyll fluorescence increase rates (FR1, i.e. O to P, and FR2 - i.e. S to M) as the parameters reflecting direct temperature effects on chloroplastic apparatus of lichen alga sensitively. We proposed that species-specific changes in the slow phase of chlorophyll fluorescence transients could be potentially used as indicators of low temperature effects in photosynthetic apparatus of lichen algal photobionts. Interspecific differences in response to low temperature might be evaluated using the approach as well.

“…The longterm research plot is located at the altitude of 8 m a.s.l. close to the coastal line (for more details see Barták et al 2015). R. melanophthalma was collected from a coastal terrace (63°48´10´´ S, 57°55´09´´ W).…”

Section: Experimental Lichensmentioning

confidence: 99%

Changes in spectral reflectance of selected Antarctic and South American lichens caused by dehydration and artificially-induced absence of secondary compounds

Barták¹,

Hájek²,

Amarillo³

et al. 2016

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Recently, spectral characteristics of lichens are in focus because of increasing number of spectral data applications in remote sensing of treeless polar and alpine regions. Therefore, species-specific spectral reflectance indices are measured in lichen species dominating polar ecosystems. Hydration status of the lichen thalli, as well as the presence of intrathalline secondary metabolites-which are UV-B absorbing compounds-both affects the spectral reflectance curves as well as numeric values of spectral reflectance indices. In the present paper, the reflectance spectra in 380-800 nm was measured in selected lichens to assess the effects of full hydration, and to evaluate the influence of secondary metabolites, they were wash out from lichen thalli with acetone (i.e. acetone rinsing) and then the spectra were also measured. For these experiments, Antarctic (Xanthoria elegans, Leptogium puberulum, Physconia muscigena and Rhizoplaca melanophthalma) and Argentinean lichens from mountain regions (Parmotrema conferendum and Ramalina celastri) were used. Changes in several spectral reflectance indices were evaluated and discussed in relation with hydration status and the absence of secondary metabolites. For the great majority of studied lichens, MCARI (Modified Chlorophyll Absorption in Reflectance Index) was the most effective index to reflect the changes between dry and wet state of thallus.