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@article{2362563,
author = {Hájek, Josef and CasanovaandKatny, Angelica and Barták, Miloš and Sekerák, Jiří},
article_location = {Brno},
article_number = {1},
doi = {http://dx.doi.org/10.5817/CPR2023-1-10},
keywords = {freezing; photosynthetic apparatus; cooling point; King George Island; differential method},
language = {eng},
issn = {1805-0689},
journal = {Czech Polar Reports},
title = {Cryoresistance of Antarctic endemic lichen Himantormia lugubris: Analysis of photosystem II functionality using a constant-rate cooling approach},
url = {https://journals.muni.cz/CPR/article/view/37053},
volume = {13},
year = {2023}
}
TY - JOUR
ID - 2362563
AU - Hájek, Josef - Casanova-Katny, Angelica - Barták, Miloš - Sekerák, Jiří
PY - 2023
TI - Cryoresistance of Antarctic endemic lichen Himantormia lugubris: Analysis of photosystem II functionality using a constant-rate cooling approach
JF - Czech Polar Reports
VL - 13
IS - 1
SP - 112-120
EP - 112-120
PB - Masaryk University
SN - 18050689
KW - freezing
KW - photosynthetic apparatus
KW - cooling point
KW - King George Island
KW - differential method
UR - https://journals.muni.cz/CPR/article/view/37053
N2 - It is well established that lichens from polar regions of the Earth are capable to perform photosynthesis at sub-zero temperatures. Majority of them show a high degree of cryoresistance, however, species-specific differences exist. Therefore, the aim of our study was to evaluate behaviour of primary photochemical processes of photosynthesis in Antarctic endemic species Himantormia lugubris at sub-zero temperature. For the purpose, the method of constant rate (2 degrees C min-1) cooling (from +20 to-40 degrees C) with simultaneous measurements of chlorophyll fluorescence parameters related to photosystem II (PSII) was used. During the cooling, potential yield of photosynthetic processes in PSII (FV/FM), and effective quantum yield of PSII (phi PSII) were measured in 30 s interval. From the FV/FM and phi PSII data sets, S-curves reflecting temperature dependence of the two chlorophyll fluorescence parameters were constructed and analyzed. The S-curves were found tri-phasic in response to sample temperature decline: (1) slight or no decline phase, (2) rapid decline phase, followed by (3) slow change reaching critical temperature at which the primary photosynthetic processes were fully inhibited. Critical temperature was found-30 and-20 degrees C for FV/FM, and phi PSII, respectively. The latter critical temperature was accompanied by an increase in background chlorophyll fluorescence (F0) indicating inhibition of energy transfer from light-harvesting complexes to core of PSII. A newly-designed chlorophyll fluorescence parameter (a differential, i.e. the difference between the maximum value-normalized FV/FM, and phi PSII) was used in order to evaluate the temperature at which the processes related to photosynthetic electron flow through thylakoid membrane carriers (phi PSII) and the energy flow through PSII (FV/FM) differed to a largest extent. This parameters proved to be temperature-dependent and useful in the evaluation of cryoresistance. Based on our study, H. lugubris, its primary photosynthetic processes in particular, might be considered as higly resistant to sub-zero temperature.
ER -
HÁJEK, Josef, Angelica CASANOVA-KATNY, Miloš BARTÁK and Jiří SEKERÁK. Cryoresistance of Antarctic endemic lichen Himantormia lugubris: Analysis of photosystem II functionality using a constant-rate cooling approach. \textit{Czech Polar Reports}. Brno: Masaryk University, 2023, vol.~13, No~1, p.~112-120. ISSN~1805-0689. Available from: https://dx.doi.org/10.5817/CPR2023-1-10.
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