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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:22 |
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Conference: Bucharest University Faculty of Physics 2004 Meeting
Section: Electricity and Biophysics
Title:
Far-red-induced thermoluminescence emission in leaves and its utility in photosynthetic system activity evaluation
Authors:
Miruna Roman1,2 and Jean-Marc Ducruet2
Affiliation:
1. INFLPR, Lasers Dept, POB MG-36, Bucuresti-Magurele, Romania
2. Service de Bioénergétique, INRA/CEA-Saclay 9119 Gif-sur-Yvette cedex, France
E-mail
Keywords:
Abstract:
A thermoluminescence (TL) emission called afterglow (AG) can be induced in intact photosynthetic material (including leaves), by a far-red illumination. It originates from those photosystem II centers initially in luminescence inactive S2/3QB state, transformed into the luminescence emitting S2/3QB- state by the back-transfer of an electron during the TL warming process that reduces the plastoquinone pool in the dark. The AG band peaking usually at about 45°C reflects this heat-induced electron transfer. Nevertheless, its peak position is depending on the state of the photosynthetic system and is often downshifted towards lower temperatures.
We analysed the downshift of the AG thermoluminescence band induced by an actinic pre-illumination or by glucose infiltration of leaf discs. We show that these two treatments, known to induce the PS-I dependent cyclic electron flow, affect also the AG band position. That suggests that one of the PS-I dependent cyclic / chlororespiratory pathways is the cause of AG emission, which occurs at lower temperature when the cyclic electron flow has been induced by glucose or by actinic light, and we discuss the possibility of using this emission to monitor the cyclic electron flow in leaves.
Also, information about the changes taking place at photosynthetic system level during the thermoluminescence signal recording (i.e. sample warming) are depicted.
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