Assessment of photosystem II thermoluminescence as a tool to investigate the effects of dehydration and rehydration on the cyclic/chlororespiratory electron pathways in wheat and barley leaves.
Thermoluminescence emission from wheat leaves was recorded under various controlled drought stress conditions: (i) fast dehydration (few hours) of excised leaves in the dark (ii) slow dehydration (several days) obtained by withholding watering of plants under a day/night cycle (iii) overnight rehydration of the slowly dehydrated plants at a stage of severe dessication. In fast dehydrated leaves, the AG band intensity was unchanged but its position was shifted to lower temperatures, indicating an activation of cyclic and chlororespiratory pathways in darkness, without any increase of their overall electron transfer capacity. By contrast, after a slow dehydration the AG intensity was strongly increased whereas its position was almost unchanged, indicating respectively that the capacity of cyclic pathways was enhanced but that they remained inactivated in darkness. Under more severe dehydration, the AG band almost disappeared. Rewatering caused its rapid bounce significantly above the control level. No significant differences in AG emission could be found between the two drought-sensitive and drought-tolerant wheat cultivars. The afterglow thermoluminescence emission in leaves provides an additional tool to follow the increased capacity and activation of cyclic electron flow around PSI in leaves during mild, severe dehydration and after rehydration.
Chamber of Agriculture of the State of North Rhine-Westphalia, Siebengebirgsstraße 200, D-53229 Bonn, Germany; University of Bonn, Institute of Crop Science and Resource Conservation - Horticultural Science, Auf dem Huegel 6, D-53121 Bonn, Germany.
Kathrin
K
Bürling
CNRS, Laboratoire Écologie, Systématique et Évolution, UMR 8079, Bât. 362, Orsay, Université Paris-Sud, 91405 Orsay, AgroParisTech, Paris 75231, France. Electronic address: jmducruet@laposte.net.
Jean-Marc
JM
Ducruet
CNRS, Laboratoire Écologie, Systématique et Évolution, UMR 8079, Bât. 362, Orsay, Université Paris-Sud, 91405 Orsay, AgroParisTech, Paris 75231, France.
Gabriel
G
Cornic
University of Bonn, Institute of Crop Science and Resource Conservation - Horticultural Science, Auf dem Huegel 6, D-53121 Bonn, Germany.
Mauricio
M
Hunsche
CNRS, Laboratoire Écologie, Systématique et Évolution, UMR 8079, Bât. 362, Orsay, Université Paris-Sud, 91405 Orsay, AgroParisTech, Paris 75231, France.
Zoran G
ZG
Cerovic
D019069:Cell Respiration; D003681:Dehydration; D004579:Electron Transport; D001467:Hordeum / Q000378:metabolism*; D049449:Luminescence; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000378:metabolism*; D013696:Temperature; D014908:Triticum / Q000378:metabolism*
D045332:Photosystem II Protein Complex
Chlororespiration; Cyclic electron flow around Photosystem I; Drought stress; Photosystems; Thermoluminescence