The effects of low temperature acclimation and photoinhibitory treatments on Photosystem 2 studied by thermoluminescence and fluorescence decay kinetics

• Published in: Photosynthesis research 1992, Vol.31 (1), p.1-10
• Main Authors: Briantais, J.M. (Universite Paris-Sud, Orsay (France). Lab. d'Ecologie Vegetale), Ducruet, J.M, Hodges, M, Krause, G.H
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; CHLOROPHYLLE; CHLOROPHYLLS; CLOROFILAS; FOTOSINTESIS; Fundamental and applied biological sciences. Psychology; Life Sciences; Metabolism; OPTICAL PROPERTIES; PHOTOSYNTHESE; PHOTOSYNTHESIS; Photosynthesis, respiration. Anabolism, catabolism; Plant physiology and development; PROPIEDADES OPTICAS; PROPRIETE OPTIQUE; SPINACIA OLERACEA; TEMPERATURA; TEMPERATURE
• ISSN: 0166-8595; 1573-5079
• DOI: 10.1007/BF00049531

The effects of low temperature acclimation and photoinhibitory treatment on Photosystem 2 (PS 2) have been studied by thermoluminescence and chlorophyll fluorescence decay kinetics after a single turnover saturating flash. A comparison of unhardened and hardened leaves showed that, in the hardened case, a decrease in overall and B-band thermoluminescence emissions occurred, indicating the presence of fewer active PS 2 reaction centers. A modification in the form of the B-band emission was also observed and is attributed to a decrease in the apparent activation energy of recombination in the hardened leaves. The acclimated leaves also produced slower QA (-) reoxidation kinetics as judged from the chlorophyll fluorescence decay kinetics. This change was mainly seen in an increased lifetime of the slow reoxidation component with only a small increase in its amplitude. Similar changes in both thermoluminescence and fluorescence decay kinetics were observed when unhardened leaves were given a high light photoinhibitory treatment at 4°C, whereas the hardened leaves were affected to a much lesser extent by a similar treatment. These results suggest that the acclimated plants undergo photoinhibition at 4°C even at low light intensities and that a subsequent high light treatment produces only a small additive photoinhibitory effect. Furthermore, it can be seen that photoinhibition eventually gives rise to PS 2 reaction centers which are no longer functional and which do not produce thermoluminescence or variable chlorophyll fluorescence.