Afterglow thermoluminescence band as a possible early indicator of changes in the photosynthetic electron transport in leaves |
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Authors: | Mercedes Roncel José M Ortega |
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Institution: | (1) Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y CSIC, Américo Vespucio 49, 41092 Sevilla, Spain |
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Abstract: | 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 °C, respectively, and a band with tmax at 41 °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 °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. |
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Keywords: | afterglow band Arabidopsis thaliana electron transfer Photosystem II thermoluminescence |
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