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Heat stress and the photosynthetic electron transport chain of the lichen Parmelina tiliacea (Hoffm.) Ach. in the dry and the wet state: differences and similarities with the heat stress response of higher plants

Oukarroum, Abdallah ; Strasser, Reto ; Schansker, Gert

In: Photosynthesis Research, 2012, vol. 111, no. 3, p. 303-314

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    Titre
    • Heat stress and the photosynthetic electron transport chain of the lichen Parmelina tiliacea (Hoffm.) Ach. in the dry and the wet state: differences and similarities with the heat stress response of higher plants
    Auteur
    • Oukarroum, Abdallah. Laboratories of Bioenergetics and Microbiology, Department of Botany and Plant Biology, University of Geneva, Chemin des Embrouchis 10, 1254, Jussy, Geneva, Switzerland
    • Strasser, Reto. Laboratories of Bioenergetics and Microbiology, Department of Botany and Plant Biology, University of Geneva, Chemin des Embrouchis 10, 1254, Jussy, Geneva, Switzerland
    • Schansker, Gert. Laboratories of Bioenergetics and Microbiology, Department of Botany and Plant Biology, University of Geneva, Chemin des Embrouchis 10, 1254, Jussy, Geneva, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Photosynthesis Research, 2012, vol. 111, no. 3, p. 303-314. Springer Netherlands
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:322334
    Summary
    Thalli of the foliose lichen species Parmelina tiliacea were studied to determine responses of the photosynthetic apparatus to high temperatures in the dry and wet state. The speed with which dry thalli were activated by water following a 24h exposure at different temperatures decreased as the temperature was increased. But even following a 24h exposure to 50°C the fluorescence induction kinetics OJIP reflecting the reduction kinetics of the photosynthetic electron transport chain had completely recovered within 128min. Exposure of dry thalli to 50°C for 24h did not induce a K-peak in the fluorescence rise suggesting that the oxygen evolving complex had remained intact. This contrasted strongly with wet thalli were submergence for 40s in water of 45°C inactivated most of the photosystem II reaction centres. In wet thalli, following the destruction of the Mn-cluster, the donation rate to photosystem II by alternative donors (e.g. ascorbate) was lower than in higher plants. This is associated with the near absence of a secondary rise peak (~1s) normally observed in higher plants. Analysing the 820nm and prompt fluorescence transients suggested that the M-peak (occurs around 2-5s) in heat-treated wet lichen thalli is related to cyclic electron transport around photosystem I. Normally, heat stress in lichen thalli leads to desiccation and as consequence lichens may lack the heat-stress-tolerance-increasing mechanisms observed in higher plants. Wet lichen thalli may, therefore, represent an attractive reference system for the evaluation of processes related with heat stress in higher plants