Cryoresistance Diff erences Between Species of Autotrops From Polar Regions Sensed by Chlorophyll Fluorescence
| Authors | |
|---|---|
| Year of publication | 2023 |
| Type | Article in Periodical |
| Magazine / Source | Problems of Cryobiology and Cryomedicine |
| MU Faculty or unit | |
| Citation | |
| Web | web stránka časopisu |
| Doi | http://dx.doi.org/10.15407/cryo33.01.025 |
| Keywords | chlorophyll fluorescence; cooling; cryoresistance; lichens; cyanobacteria; polar regions; photosystem II; photosynthesis |
| Description | Lichens from the cold regions of Earth exhibit high, but diff erent degree of tolerance to drought and freeze stresses. Therefore, three lichen species Xanthoria elegans, Umbilicaria cylindrica, Usnea sphacelata, and a representative of extre-mophilic cyanobacteria Nostoc commune were selected to measure temperature response curves of chlorophyll fl uorescence para-meters in cooling experiment using a constant rate of cooling from 20 to –45°C. Two chlorophyll fl uorescence parameters (FV/FM – potential yield of photosynthetic processes in photosystem II and ?PSII – eff ective quantum yield) were measured with a modulated fl uorometer. For all experimental species, the temperature-response curves of II FV/FM and ?PSII showed typical triphasic shape: plateau (temperature decrease from 20 to –5°C), decline, and a shoulder reaching the critical point. The phase typically formed a S-curve of diff erent shape as dependent on species and chlorophyll fl uorescence parameter. U. cylindrica was the most cryoresistant in terms of photosynthetic processes ongoing in thylakoid membrane of chloroplast at below zero temperature |
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