Scientific article
Open access

Quantification of non-QB-reducing centers in leaves using a far-red pre-illumination

Published inPhotosynthesis Research, vol. 84, no. 1-3, p. 145-151
  • Open Access - Licence nationale Springer 
Publication date2005

An alternative approach to quantification of the contribution of non-Q B -reducing centers to Chl a fluorescence induction curve is proposed. The experimental protocol consists of a far-red pre-illumination followed by a strong red pulse to determine the fluorescence rise kinetics. The far-red pre-illumination induces an increase in the initial fluorescence level (F25 μs) that saturates at low light intensities indicating that no light intensity-dependent accumulation of Q A − occurs. Far-red light-dose response curves for the F25 μs-increase give no indication of superimposed period-4 oscillations. F25 μs-dark-adaptation kinetics following a far-red pre-pulse, reveal two components: a faster one with a half-time of a few seconds and a slower component with a half-time of around 100 s. The faster phase is due to the non-Q B -reducing centers that re-open by recombination between Q A − and the S-states on the donor side. The slower phase is due to the recombination between Q B − and the donor side in active PS II reaction centers. The pre-illumination-induced increase of the F25 μs-level represents about 4–5% of the variable fluorescence for pea leaves (∼2.5% equilibrium effect and 1.8–3.0% non-Q B -reducing centers). For the other plant species tested these values were very similar. The implications of these values will be discussed.

Citation (ISO format)
SCHANSKER, Geert, STRASSER, Reto. Quantification of non-QB-reducing centers in leaves using a far-red pre-illumination. In: Photosynthesis Research, 2005, vol. 84, n° 1-3, p. 145–151. doi: 10.1007/s11120-004-7156-z
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ISSN of the journal0166-8595

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