Combination of dehydration and high light exposure effects on PSII photochemistry in three Antarctic moss species
Abstract
Background and Aims: Mosses stand out for their ability to sustain photosynthetic activity even when exposed to extreme stress. They have developed intricate protective strategies that safeguard photosynthesis from dehydration, excessive light and oxidative stress. While considerable progress has been made in understanding how dehydration and high light each affect PSII photochemistry, their combined influence on Antarctic mosses is still not well characterized. The present study examines how simultaneous dehydration and high light exposure influence PSII function in three Antarctic moss species: Bryum pseudotriquetrum, Hypnum revolutum and Sanionia uncinata.
Methods: Chlorophyll fluorescence parameters, including FV/FM, ΦPSII, RFd, NPQ, qE and qI, were measured under controlled dehydration and high light treatments at the Mendel Polar Station on James Ross Island in the Antarctic peninsula; the obtained curves were analysed with generalized additive mixed models.
Key Results: The results showed species-specific responses to the combined stress, displayed as a difference in curve shape, and a strong influence of high light on the desiccation curves’ shapes. Bryum pseudotriquetrum exhibited higher PSII performances under low light while S. uncinata showed a less rapid decline in photosynthetic efficiency under high light exposure and a lower NPQ decline in response to high light compared with the other species. It was observed that high light can strongly affect photosynthesis by enhancing the rate at which photosynthetic efficiency declines and at the same time induces a faster increase in photoinhibition-related quenching (i.e. qI).
Conclusions: This study highlights interspecific differences among Antarctic mosses in their sensitivity to photoinhibition during thallus desiccation. Thus, light exposure during desiccation is an important factor to be considered in future ecophysiological studies. Finally, this study also emphasizes the need to examine both intra- and interspecific variability and the molecular and physiological mechanisms driving stress tolerance and adaptation in these species.
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BibTeX
@article{giordano2026combination,
title = {{Combination of dehydration and high light exposure effects on PSII photochemistry in three Antarctic moss species}},
author = {Davide Giordano and Syed Inzimam Ul Haq and Josef Hajek and Milos Bartak},
journal = {Annals of Botany},
year = {2026},
month = jul,
doi = {10.1093/aob/mcag207},
url = {https://doi.org/10.1093/aob/mcag207},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Combination of dehydration and high light exposure effects on PSII photochemistry in three Antarctic moss species
AU - Davide Giordano
AU - Syed Inzimam Ul Haq
AU - Josef Hajek
AU - Milos Bartak
PY - 2026
DA - 2026/07/10
JO - Annals of Botany
DO - 10.1093/aob/mcag207
UR - https://doi.org/10.1093/aob/mcag207
AB - Background and Aims: Mosses stand out for their ability to sustain photosynthetic activity even when exposed to extreme stress. They have developed intricate protective strategies that safeguard photosynthesis from dehydration, excessive light and oxidative stress. While considerable progress has been made in understanding how dehydration and high light each affect PSII photochemistry, their combined influence on Antarctic mosses is still not well characterized. The present study examines how simultaneous dehydration and high light exposure influence PSII function in three Antarctic moss species: Bryum pseudotriquetrum, Hypnum revolutum and Sanionia uncinata. Methods: Chlorophyll fluorescence parameters, including FV/FM, ΦPSII, RFd, NPQ, qE and qI, were measured under controlled dehydration and high light treatments at the Mendel Polar Station on James Ross Island in the Antarctic peninsula; the obtained curves were analysed with generalized additive mixed models. Key Results: The results showed species-specific responses to the combined stress, displayed as a difference in curve shape, and a strong influence of high light on the desiccation curves’ shapes. Bryum pseudotriquetrum exhibited higher PSII performances under low light while S. uncinata showed a less rapid decline in photosynthetic efficiency under high light exposure and a lower NPQ decline in response to high light compared with the other species. It was observed that high light can strongly affect photosynthesis by enhancing the rate at which photosynthetic efficiency declines and at the same time induces a faster increase in photoinhibition-related quenching (i.e. qI). Conclusions: This study highlights interspecific differences among Antarctic mosses in their sensitivity to photoinhibition during thallus desiccation. Thus, light exposure during desiccation is an important factor to be considered in future ecophysiological studies. Finally, this study also emphasizes the need to examine both intra- and interspecific variability and the molecular and physiological mechanisms driving stress tolerance and adaptation in these species.
SN - 0305-7364
SN - 1095-8290
ER -