Desiccation-induced non-radiative dissipation in isolated green lichen algae.

Wieners, Paul Christian, Mudimu, Opayi and Bilger, Wolfgang (2012) Desiccation-induced non-radiative dissipation in isolated green lichen algae. Photosynthesis Research, 113 (1-3). pp. 239-247. DOI 10.1007/s11120-012-9771-4.

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Lichens are able to tolerate almost complete desiccation and can quickly resume metabolic activity after rehydration. In the desiccated state, photosynthesis is completely blocked and absorbed excitation energy cannot be used for electron transport, leading to a potential strong vulnerability for high light damage. Although desiccation and high insolation often occur simultaneously and many lichens colonize exposed habitats, these organisms show surprisingly little photodamage. In the desiccated state, variable chlorophyll fluorescence is lost, indicating a suspension of charge separation in photosystem II. At the same time, basal fluorescence (F 0) is strongly quenched, which has been interpreted as an indication for high photoprotective non-radiative dissipation (NRD) of absorbed excitation energy. In an attempt to provide evidence for a photoprotective function of NRD in the desiccated state, isolated green lichen algae of the species Coccomyxa sp. and Trebouxia asymmetrica were used as experimental system. In contrast to experiments with intact lichens this system provided high reproducibility of the data without major optical artifacts on desiccation. The presence of 5 mM trehalose during desiccation had no effect but culture of the algae in seawater enhanced F 0 quenching in T. asymmetrica together with a reduced depression of F V/F M after high light treatment. While this effect could not be induced using artificial seawater medium lacking trace elements, the addition of ZnCl2 and NaI in small amounts to the normal growth medium led to qualitatively and quantitatively identical results as with pure seawater. It is concluded that NRD indicated by F 0 quenching is photoprotective. The formation of NRD in lichen algae is apparently partially dependent on the presence of specific micronutrients.

Document Type: Article
Keywords: Desiccation, Iodine, Micronutrients, Non-photochemical Quenching, Trebouxia, Zinc
Research affiliation: Kiel University > Kiel Marine Science
OceanRep > The Future Ocean - Cluster of Excellence
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1007/s11120-012-9771-4
ISSN: 0166-8595
Projects: Future Ocean
Date Deposited: 14 May 2014 09:07
Last Modified: 30 Jul 2019 07:04

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