TY - JOUR
T1 - Exposure times in rapid light curves affect photosynthetic parameters in algae
AU - Ihnken, Sven Soren
AU - Eggert, Anja
AU - Beardall, John
PY - 2010
Y1 - 2010
N2 - Short-and long-duration light curves were applied to four macroalgae (Ulva sp., Codium fragile, Ecklonia radiata and Lessonia variegata), and two microalgal species (Chlorella emersonii and Chaetoceros muellerii). With increasing light curve duration, the maximal relative electron transport rate increased by a factor of three in E. radiata, and by factors of 1.25 and 1.23 in C. emersonii and L. variegata, respectively, but did not change in C. fragile and Ch. muellerii. The light saturation point E-k increased by 26 mu mol photons m(-2) s(-1) in C. emersonii and 20 mu mol photons m(-2) s(-1) in Ch. muellerii and E. radiata with elevated light curve exposure times. Oscillatory patterns of the continuous fluorescence readings reflect accumulation of Q(A). Continuous fluorescence values increased, or decreased, by approximately 10 within light curve increments. However, oscillations of 25 were not uncommon, which shows that cells are changing their photo-physiological response state during steady light conditions. Increasing dark acclimation times prior to light curve application lowered maximal relative electron transport rates in the C. emersonii (from 28 +/- 1.7 to 25 +/- 1.2 for 15 and 95 min dark acclimation in short-duration light curves respectively). This effect was counterbalanced by longer light curve application. It can therefore be concluded that manipulation of light exposure and dark incubation prior to the experiment affects the photosynthetic response, presumably due to different activation states of photosynthetic and photoprotective mechanisms. The highly species-specific photo-response patterns imply that a common rapid light curve protocol will generate artefacts in some species.
AB - Short-and long-duration light curves were applied to four macroalgae (Ulva sp., Codium fragile, Ecklonia radiata and Lessonia variegata), and two microalgal species (Chlorella emersonii and Chaetoceros muellerii). With increasing light curve duration, the maximal relative electron transport rate increased by a factor of three in E. radiata, and by factors of 1.25 and 1.23 in C. emersonii and L. variegata, respectively, but did not change in C. fragile and Ch. muellerii. The light saturation point E-k increased by 26 mu mol photons m(-2) s(-1) in C. emersonii and 20 mu mol photons m(-2) s(-1) in Ch. muellerii and E. radiata with elevated light curve exposure times. Oscillatory patterns of the continuous fluorescence readings reflect accumulation of Q(A). Continuous fluorescence values increased, or decreased, by approximately 10 within light curve increments. However, oscillations of 25 were not uncommon, which shows that cells are changing their photo-physiological response state during steady light conditions. Increasing dark acclimation times prior to light curve application lowered maximal relative electron transport rates in the C. emersonii (from 28 +/- 1.7 to 25 +/- 1.2 for 15 and 95 min dark acclimation in short-duration light curves respectively). This effect was counterbalanced by longer light curve application. It can therefore be concluded that manipulation of light exposure and dark incubation prior to the experiment affects the photosynthetic response, presumably due to different activation states of photosynthetic and photoprotective mechanisms. The highly species-specific photo-response patterns imply that a common rapid light curve protocol will generate artefacts in some species.
UR - http://linkinghub.elsevier.com/retrieve/pii/S0304377010000823
U2 - 10.1016/j.aquabot.2010.07.002
DO - 10.1016/j.aquabot.2010.07.002
M3 - Article
SN - 0304-3770
VL - 93
SP - 185
EP - 194
JO - Aquatic Botany
JF - Aquatic Botany
IS - 3
ER -