MEPS 422:51-62 (2011)  -  doi:10.3354/meps08913

Photosystem II breakdown induced by reactive oxygen species in freshly-isolated Symbiodinium from Montipora (Scleractinia; Acroporidae)

J.-T. Wang1,*, P.-J. Meng2,3, E. Sampayo4, S.-L. Tang5, C. A. Chen5,6,7

1The Graduate Institute of Biotechnology, Tajen University, Pingtung 907, Taiwan
2National Museum of Marine Biology and Aquarium, Pingtung 944, Taiwan
3Institute of Marine Biodiversity and Evolution, National Dong Hwa University, Checheng, Pingtung 944, Taiwan
4Mueller Laboratory, Department of Biology, Pennsylvania State University, Pennsylvania 16802, USA
5Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
6Institute of Oceanography, National Taiwan University, Taipei 108, Taiwan
7ARC Centre for Coral Reef Studies, James Cook University, Townsville, Queensland 4810, Australia

ABSTRACT: Freshly-isolated Symbiodinium (FIS) have been used to study cnidarian–alga symbiosis based on the assumption that their physiological performance is comparable to that of the algae in hospite. This assumption was tested with 15 species of scleractinian corals, using pulse-amplitude modulation (PAM) chlorophyll a (chl a) fluorescence to compare maximum quantum yields (Fv/Fm) of photosystem II (PSII) in Symbiodinium in hospite and after isolation in seawater. FIS from Montipora spp. exhibited rapid and dramatic decreases (by up to >95%) in PSII activity within 30 min of isolation. In contrast, PSII activities of FIS from 8 other coral species decreased by only 5 to 21% after >4 h in seawater. To investigate possible reasons for this variation, the variation in Symbiodinium genetic type (ITS-2 types), transmission modes and several physiological indices were considered. The rapid loss of PSII activity in FIS from Montipora spp. was not correlated with Symbiodinium ITS-2 type, the mode of symbiont transmission, or ionic regulation capability, nor could consistent chemical effects in host extracts be demonstrated. PSII inactivation was correlated with increased levels of reactive oxygen species (ROS), degradation of pigments in peridinin-chl a protein, and chloroplast disruption, indicating that the FIS was under physiological collapse. The specific mechanism(s) causing Montipora-associated Symbiodinium to fail during the isolation methods used here remain unknown. However, these data indicate that care should be taken when using FIS to represent Symbiodinium in hospite, especially when comparing different species of corals.

KEY WORDS: Montipora · Symbiodinium · PSII inactivation · ROS · Symbiont transmission mode ·    Host extract · Cnidarian · Symbiosis

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Cite this article as: Wang JT, Meng PJ, Sampayo E, Tang SL, Chen CA (2011) Photosystem II breakdown induced by reactive oxygen species in freshly-isolated Symbiodinium from Montipora (Scleractinia; Acroporidae). Mar Ecol Prog Ser 422:51-62

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