Demonstration of thermal dissipation of absorbed quanta during energy‐dependent quenching of chlorophyll fluorescence in photosynthetic membranes

FEBS Letters

Carpentier, Robert¹  Yahyaoui, Wafaa¹  Harnois, Johanne¹ 

[1] Groupe de Recherche en Energie et Information Biomoléculaires, Université du Québec à Trois-Rivières, P.O. Box 500, Trois-Rivières, Que. G9A 5H7, Canada

关键词: Non-photochemical fluorescence quenching;    Photoacoustic spectroscopy;    Thylakoid membrane;    Photosynthesis;    Proton gradient;    Xanthophyll;   

DOI  :  10.1016/S0014-5793(98)01430-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

When plant leaves or chloroplasts are exposed to illumination that exceeds their photosynthetic capacity, photoprotective mechanisms such as described by the energy-dependent (non-photochemical) quenching of chlorophyll fluorescence are involved. The protective action is attributed to an increased rate constant for thermal dissipation of absorbed quanta. We applied photoacoustic spectroscopy to monitor thermal dissipation in spinach thylakoid membranes together with simultaneous measurement of chlorophyll fluorescence in the presence of inhibitors of opposite action on the formation of ΔpH across the thylakoid membrane (tentoxin and nigericin/valinomycin). A linear relationship between the appearance of fluorescence quenching during formation of the ΔpH and the reciprocal variation of thermal dissipation was demonstrated. Dicyclohexylcarbodiimide, which is known to prevent protonation of the minor light-harvesting complexes of photosystem II, significantly reduced the formation of fluorescence quenching and the concurrent increase in thermal dissipation. However, the addition of exogenous ascorbate to activate the xanthophyll de-epoxidase increased non-photochemical fluorescence quenching without affecting the measured thermal dissipation. It is concluded that a portion of energy-dependent fluorescence quenching that is independent of de-epoxidase activity can be readily measured by photoacoustic spectroscopy as an increase in thermal deactivation processes.

【 授权许可】

Unknown