In:
PLOS ONE, Public Library of Science (PLoS), Vol. 18, No. 9 ( 2023-9-28), p. e0292211-
Abstract:
Microphytobenthos (MPB) inhabiting intertidal flats are exposed to large and sudden changes in temperature, often simultaneously with exposure to direct sunlight. These conditions are expected to negatively impact photosynthesis by exacerbating the photoinhibition under high light. This study addressed the photoinhibitory effects of short-term exposure to cold (5°C) and moderate heat (35°C) on MPB dominated by motile epipelic (EPL) and immotile epipsammic (EPM) diatom species, by evaluating the seasonal variation of photoinactivation and repair of photosystem II (PSII). The susceptibility to PSII photoinactivation and the counteracting repair capacity were measured by the constant rates k PI and k REC , respectively. The photoacclimation state was characterized by hysteresis light-response curves (HLC) of the relative electron transport rate, rETR, and of the nonphotochemical quenching index Y(NPQ). Under non-stress conditions (20°C), k REC was on average almost 10x higher than the corresponding k PI (20.4 vs 2.70 × 10 −4 s −1 , respectively), indicating the operation of efficient repair mechanisms. Overall, the exposure to low and high temperatures affected both PSII photoinactivation and repair but causing smaller impacts in the former than in the latter. Also, cold stress caused larger effects on repair (decrease of k REC ) than on photoinactivation (increase of k PI ), but heat stress affected similarly the two processes. These effects varied seasonally, suggesting a role of thermal acclimation, as heat stress had stronger effects in cold-acclimated samples and cold stress resulted in stronger effects in heat-acclimated samples. The changes in k PI and k REC occurred despite the high light-acclimated phenotype found all year round, indicating that these processes vary independently from the photoacclimation state. The results also showed that photoprotection processes, as measured by energy-dependent non-photochemical index q E , appear to have an important role, both by preventing PSII photoinactivation and by alleviating the impacts on PSII repair under acute thermal stress.
Type of Medium:
Online Resource
ISSN:
1932-6203
DOI:
10.1371/journal.pone.0292211
DOI:
10.1371/journal.pone.0292211.g001
DOI:
10.1371/journal.pone.0292211.g002
DOI:
10.1371/journal.pone.0292211.g003
DOI:
10.1371/journal.pone.0292211.g004
DOI:
10.1371/journal.pone.0292211.g005
DOI:
10.1371/journal.pone.0292211.g006
DOI:
10.1371/journal.pone.0292211.g007
DOI:
10.1371/journal.pone.0292211.g008
DOI:
10.1371/journal.pone.0292211.t001
DOI:
10.1371/journal.pone.0292211.t002
DOI:
10.1371/journal.pone.0292211.t003
DOI:
10.1371/journal.pone.0292211.s001
Language:
English
Publisher:
Public Library of Science (PLoS)
Publication Date:
2023
detail.hit.zdb_id:
2267670-3
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