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Kinetics of Photosynthetic Response to Ultraviolet and Photosynthetically Active Radiation in Synechococcus WH 8102 ( CYANOBACTERIA )
Author(s) -
Fragoso Glaucia M.,
Neale Patrick J.,
Kana Todd M.,
Pritchard Alicia L.
Publication year - 2013
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12202
Subject(s) - photoprotection , photosynthetically active radiation , photosynthesis , photosystem ii , cyanobacteria , quantum yield , synechococcus , chemistry , photochemistry , phycocyanin , photobioreactor , chlorophyll fluorescence , botany , biophysics , biochemistry , biology , fluorescence , bacteria , ecology , physics , biomass (ecology) , quantum mechanics , genetics
The picoplanktonic cyanobacteria, Synechococcus spp., (Nägeli) are important contributors to global ocean primary production that can be stressed by solar radiation, both in the photosynthetically active ( PAR ) and ultraviolet ( UV ) range. We studied the responses of PSII quantum yield (active fluorescence), carbon fixation ( 14 C assimilation) and oxygen evolution (membrane inlet mass spectrometry) in Synechococcus WH 8102 under moderate UV and PAR . PSII quantum yield decreased during exposure to moderate UV and UV + PAR , with response to the latter being faster (6.4 versus 2.8 min, respectively). Repair processes were also faster when UV + PAR exposure was followed by moderate PAR (1.68 min response time) than when UV was followed by very low PAR (10.5 min response time). For the UV + PAR treatment, the initial decrease in quantum yield was followed by a 50% increase (“rebound”) after 7 min exposure, showing an apparent photoprotection induction. While oxygen uptake increased with PAR , it did not change under UV , suggesting that this oxygen‐dependent mechanism of photoprotection, which may be acting as an electron sink, is not an important strategy against UV . We used propyl gallate, an antioxidant, to test for plastid terminal oxidase (ptox) or ptox‐like enzymes activity, but it caused nonspecific and toxic effects on Synechococcus WH 8102.