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Roles of alternative electron flows to O2 and non-photochemical quenching during photosynthesis in the seagrass Zostera marina
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
(English)Manuscript (preprint) (Other academic)
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:su:diva-100156OAI: oai:DiVA.org:su-100156DiVA: diva2:691536
Available from: 2014-01-28 Created: 2014-01-28 Last updated: 2014-01-28Bibliographically approved
In thesis
1. Beyond carbon-limitation: A re-evaluation of the ecological role of photorespiration and direct oxygen photoreduction in seagrasses
Open this publication in new window or tab >>Beyond carbon-limitation: A re-evaluation of the ecological role of photorespiration and direct oxygen photoreduction in seagrasses
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Seagrasses living in shallow coastal waters are regularly subjected to changes in environmental conditions including the two essential factors for photosynthesis: dissolved inorganic carbon (DIC) and irradiance. This thesis focuses on the photosynthetic responses of seagrasses to carbon limitation induced by community metabolism and/or high light intensities. Field sampling conducted in seagrass-dominated embayments along the Swedish west coast revealed that high pH and low levels of DIC caused by community photosynthesis are common in shallow coastal waters. These effects were found on a scale of a whole bay and were affected by the composition of the vegetation. Such carbon limitation and at the same time an increase in O2 concentration negatively affected photosynthesis of the seagrass species Zostera marina L. and Ruppia maritima L. by compromising carbon assimilation as well as enhancing photorespiration.  In contrast to the results from the two seagrasses, it was found that gross photosynthetic rates did not increase under low O2 concentrations in the green alga Ulva intestinalis L., suggesting that its efficient carbon acquisition mechanisms are able to suppress photorespiration. The role of photorespiration in seagrass photosynthesis was further investigated in Z. marina. It was found that under conditions of carbon limitation, photorespiration provides the major alternative sink for electrons, sustaining substantial electron transport via photosystem II while the Mehler reaction has a smaller contribution as an alternative electron sink. Photorespiration was however not a significant component of the photoprotective mechanisms in Z. marina under high irradiance. Here the down-regulation of electron transport via non-photochemical quenching appeared to be the more efficient mechanism for dissipating excess energy. Overall, this study highlights the role of O2 in seagrass photosynthesis which appears to be of greater importance than previously envisaged, particularly in the productive waters where carbon availability is occasionally limited. 

Place, publisher, year, edition, pages
Stockholm: Department of Ecology, Environment and Plant Sciences, Stockholm University, 2014. 49 p.
Keyword
Carbon limitation, Chlorophyll fluorescence, Electron transport rate, Irradiance, Mehler reaction, Non-photochemical quenching, Photorespiration, Photosynthetic activity
National Category
Botany
Research subject
Plant Physiology
Identifiers
urn:nbn:se:su:diva-99434 (URN)978-91-7447-850-1 (ISBN)
Public defence
2014-02-21, Föreläsningssalen, Institutionen för Ekologi, Miljö och Botanik, Lilla Frescativägen 5, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2014-01-30 Created: 2014-01-13 Last updated: 2014-01-28Bibliographically approved

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CiteExportLink to record
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