Effective light absorption and absolute electron transport rates in the coral Pocillopora damicornis

Szabó, M; Wangpraseurt, D; Tamburic, B; Larkum, AWD; Schreiber, U; Suggett, DJ; Kühl, M; Ralph, PJ

Effective light absorption and absolute electron transport rates in the coral Pocillopora damicornis

Szabó, M

Wangpraseurt, D

Tamburic, B

Larkum, AWD

Schreiber, U Suggett, DJ

Kühl, M

Ralph, PJ

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Publication Type:: Journal Article
Citation:: Plant Physiology and Biochemistry, 2014, 83 pp. 159 - 167
Issue Date:: 2014-01-01

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Field	Value	Language
dc.contributor.author	Szabó, M https://orcid.org/0000-0001-6235-2894	en_US
dc.contributor.author	Wangpraseurt, D https://orcid.org/0000-0003-4834-8981	en_US
dc.contributor.author	Tamburic, B https://orcid.org/0000-0001-5720-9380	en_US
dc.contributor.author	Larkum, AWD https://orcid.org/0000-0002-0420-134X	en_US
dc.contributor.author	Schreiber, U	en_US
dc.contributor.author	Suggett, DJ https://orcid.org/0000-0001-5326-2520	en_US
dc.contributor.author	Kühl, M https://orcid.org/0000-0002-1792-4790	en_US
dc.contributor.author	Ralph, PJ https://orcid.org/0000-0002-3103-7346	en_US
dc.date.available	2020-05-25T19:04:22Z
dc.date.issued	2014-01-01	en_US
dc.identifier.citation	Plant Physiology and Biochemistry, 2014, 83 pp. 159 - 167	en_US
dc.identifier.issn	0981-9428	en_US
dc.identifier.uri	http://hdl.handle.net/10453/34702
dc.description.abstract	Pulse Amplitude Modulation (PAM) fluorometry has been widely used to estimate the relative photosynthetic efficiency of corals. However, both the optical properties of intact corals as well as past technical constrains to PAM fluorometers have prevented calculations of the electron turnover rate of PSII. We used a new Multi-colour PAM (MC-PAM) in parallel with light microsensors to determine for the first time the wavelength-specific effective absorption cross-section of PSII photochemistry, σII(λ), and thus PAM-based absolute electron transport rates of the coral photosymbiont Symbiodinium both in culture and in hospite in the coral Pocillopora damicornis. In both cases, σII of Symbiodinium was highest in the blue spectral region and showed a progressive decrease towards red wavelengths. Absolute values for σII at 440nm were up to 1.5-times higher in culture than in hospite. Scalar irradiance within the living coral tissue was reduced by 20% in the blue when compared to the incident downwelling irradiance. Absolute electron transport rates of P.damicornis at 440nm revealed a maximum PSII turnover rate of ca. 250 electrons PSII-1 s-1, consistent with one PSII turnover for every 4 photons absorbed by PSII; this likely reflects the limiting steps in electron transfer between PSII and PSI. Our results show that optical properties of the coral host strongly affect light use efficiency of Symbiodinium. Therefore, relative electron transport rates do not reflect the productivity rates (or indeed how the photosynthesis-light response is parameterised). Here we provide a non-invasive approach to estimate absolute electron transport rates in corals. © 2014 Elsevier Masson SAS.	en_US
dc.relation.ispartof	Plant Physiology and Biochemistry	en_US
dc.relation.isbasedon	10.1016/j.plaphy.2014.07.015	en_US
dc.subject.classification	Plant Biology & Botany	en_US
dc.subject.mesh	Animals	en_US
dc.subject.mesh	Anthozoa	en_US
dc.subject.mesh	Electron Transport	en_US
dc.subject.mesh	Light	en_US
dc.title	Effective light absorption and absolute electron transport rates in the coral Pocillopora damicornis	en_US
dc.type	Journal Article
utslib.citation.volume	83	en_US
utslib.for	060702 Plant Cell and Molecular Biology	en_US
utslib.for	0503 Soil Sciences	en_US
utslib.for	0607 Plant Biology	en_US
pubs.embargo.period	Not known	en_US
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Science
pubs.organisational-group	/University of Technology Sydney/Strength - C3 - Climate Change Cluster
utslib.copyright.status	open_access
pubs.publication-status	Published	en_US
pubs.volume	83	en_US

Abstract:

Pulse Amplitude Modulation (PAM) fluorometry has been widely used to estimate the relative photosynthetic efficiency of corals. However, both the optical properties of intact corals as well as past technical constrains to PAM fluorometers have prevented calculations of the electron turnover rate of PSII. We used a new Multi-colour PAM (MC-PAM) in parallel with light microsensors to determine for the first time the wavelength-specific effective absorption cross-section of PSII photochemistry, σII(λ), and thus PAM-based absolute electron transport rates of the coral photosymbiont Symbiodinium both in culture and in hospite in the coral Pocillopora damicornis. In both cases, σII of Symbiodinium was highest in the blue spectral region and showed a progressive decrease towards red wavelengths. Absolute values for σII at 440nm were up to 1.5-times higher in culture than in hospite. Scalar irradiance within the living coral tissue was reduced by 20% in the blue when compared to the incident downwelling irradiance. Absolute electron transport rates of P.damicornis at 440nm revealed a maximum PSII turnover rate of ca. 250 electrons PSII-1 s-1, consistent with one PSII turnover for every 4 photons absorbed by PSII; this likely reflects the limiting steps in electron transfer between PSII and PSI. Our results show that optical properties of the coral host strongly affect light use efficiency of Symbiodinium. Therefore, relative electron transport rates do not reflect the productivity rates (or indeed how the photosynthesis-light response is parameterised). Here we provide a non-invasive approach to estimate absolute electron transport rates in corals. © 2014 Elsevier Masson SAS.

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