Afterglow thermoluminescence band as a possible early indicator of changes in the photosynthetic electron transport in leaves.
The afterglow (AG) band of thermoluminescence (TL) has been investigated in leaves of Arabidopsis thaliana. Excitation of dark-adapted leaves with two saturating single turn-over flashes induced the appearance of a complex TL glow curve that could be well simulated by three components: the two components, B1 and B2, of the usually called B-band, peaking at 18 and 26 degrees C, respectively, and a band with tmax at 41 degrees C, which we attributed to an AG emission. Illumination of dark-adapted leaves with 720 nm monochromatic and FR lights generated the emission of a sharp single band peaking also around at 41 degrees C, that it is usually assigned to an AG emission band. Dark-incubation of whole plants increased the intensity of AG-band in TL curves induced by two flashes and, in parallel, decreased B-bands. Selective illumination of leaves with light mostly absorbed by PS II (650 nm light) completely abolished the AG-band induced by two flashes, B-band being the only TL band observed. The single AG-band induced by 720 nm light was abolished if leaves were also illuminated with 650 nm light. On the other hand, AG-band could be restored if 650 nm illuminated leaves were afterwards illuminated with 720 nm light. The changes in the intensity of B and AG bands induced by selective illuminations seem to be related to alterations in the redox state of QB and plastoquinone pool.
Roncel
Mercedes
M
Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y CSIC, Américo Vespucio 49, 41092 Sevilla, Spain. mroncel@us.es
Ortega
José M
JM
D017360:Arabidopsis / Q000378:metabolism*; D004579:Electron Transport; D008027:Light; D049449:Luminescence; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D013696:Temperature
D045332:Photosystem II Protein Complex