Effects of far-red light on fluorescence induction in infiltrated pea leaves under diminished ΔpH and Δφ components of the proton motive force
- 255 Downloads
Chlorophyll fluorescence induction curves induced by an actinic pulse of red light follow different kinetics in dark-adapted plant leaves and leaves preilluminated with far-red light. This influence of far-red light was abolished in leaves infiltrated with valinomycin known to eliminate the electrical (Δφ) component of the proton-motive force and was strongly enhanced in leaves infiltrated with nigericin that abolishes the ΔpH component. The supposed influence of ionophores on different components of the proton motive force was supported by differential effects of these ionophores on the induction curves of the millisecond component of chlorophyll delayed fluorescence. Comparison of fluorescence induction curves with the kinetics of P700 oxidation in the absence and presence of ionophores suggests that valinomycin facilitates a build-up of a rate-limiting step for electron transport at the site of plastoquinone oxidation, whereas nigericin effectively removes limitations at this site. Far-red light was found to be a particularly effective modulator of electron flows in chloroplasts in the absence of ΔpH backpressure on operation of the electron-transport chain.
KeywordsInfiltrated leaves Thylakoid membrane Proton motive force Ionophores Chlorophyll fluorescence P700 redox transients
Unable to display preview. Download preview PDF.
- Kramer DM, Crofts AR (1996) Control and measurement of photosynthetic transport in vivo. In: Baker NR (ed) Photosynthesis and environment. Springer, Dordrecht, pp 25–66Google Scholar
- Tyystjarvi E, Vass I (2004) Light emission as a probe of charge separation and recombination in the photosynthetic apparatus: Relation of prompt fluorescence to delayed light emission and thermoluminescence. In: Papageorgiou G (ed) Chlorophyll fluorescence: a signature of photosynthesis. Springer, Dordrecht, pp 363–388CrossRefGoogle Scholar