Different thermal sensitivity of the repair of photodamaged photosynthetic machinery in cultured Symbiodinium species

Date

2009

Authors

Takahashi, Shunichi
Whitney, Spencer
Badger, Murray

Journal Title

Journal ISSN

Volume Title

Publisher

National Academy of Sciences (USA)

Abstract

Coral bleaching caused by heat stress is accompanied by photoinhibition, which occurs under conditions where the rate of photodamage to photosystem II (PSII) exceeds the rate of its repair, in the symbiotic algae (Symbiodinium spp.) within corals. However, the mechanism of heat stress-induced photoinhibition in Symbiodinium still remains poorly understood. In the present work, we have investigated the effect of elevated temperature on the processes associated with the repair of photodamaged PSII in cultured Symbiodinium (OTcH-1 and CS-73). Severe photoinhibition was observed at temperature exceeding 32°C in Symbiodinium CS-73 cells grown at 25-34°C but not in cultures of the more thermally tolerant Symbiodinium OTcH-1. After photoinhibition treatment by strong light, photodamaged PSII was repaired close to initial levels under low light at 25°C in both OTcH-1 and CS-73. However, the repair was strongly inhibited by increased temperature exceeding 31°C in CS-73 but only weakly in OTcH-1. We found that inhibition of the repair process in CS-73 is attributed to impairment of both protein synthesis-dependent and -independent repair processes and is at least partially caused by suppression of the de novo synthesis of thylakoid membrane proteins and impairment of the generation of ΔpH across the thylakoid membrane, respectively. Our results suggest that acceleration of photoinhibition by moderate heat stress is attributed primarily to inhibition of the repair of photodamaged PSII and that the photoinhibition sensitivity of Symbiodinium to heat stress is determined by the thermal sensitivity of the PSII repair processes.

Description

Keywords

Keywords: membrane protein; alga; article; bleaching; cell culture; cell growth; controlled study; coral; heat sensitivity; heat stress; nonhuman; photoinhibition; photosystem II; plant stress; priority journal; thylakoid membrane; Algae; Algal Proteins; Aquacultur Coral bleaching; Heat stress; Photoinhibition; Photosystem II; Zooxanthellae

Citation

Source

PNAS - Proceedings of the National Academy of Sciences of the United States of America

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1073/pnas.0808363106

Restricted until

2037-12-31