Identification of far-red-induced relative increase in the decay of delayed light emission from photosynthetic membranes with thermoluminescence peak V appearing at 321 K

Photosynthesis in Microalgae as Measured with Delayed Fluorescence Technique

“…The emission is composed of several components, characterized by different decay rates (Bjorn, 1971;Desai et al, 1983). The faster decaying components (first few seconds) provide information about the fate of energy absorbed by PSII (Desai et al, 1983).…”

“…The emission is composed of several components, characterized by different decay rates (Bjorn, 1971;Desai et al, 1983). The faster decaying components (first few seconds) provide information about the fate of energy absorbed by PSII (Desai et al, 1983). The slow components (from few seconds to minutes or hours) originate in back reactions in the photosynthetic chain as well as between the S2 and S3 states of the oxygen evolving complex (OEC) and quinones Q A and Q B (Joliot et al, 1971).…”

“…The slow components probably provide information on temporary energy storage during the photosynthetic electron transport (Desai et al, 1983), because they depend on electron distribution in the plastoquinone pool (PQ) and photosystem I (PSI) (Katsumata et al, 2006). By a measurement of the fluorescent yield it is possible to monitor the reduction state of quinone Q A in PSII.…”

“…This experiment showed the occurrence of transient peaks represents an important physiological parameter for investigation of photosynthetic processes. The occurrence of the transient peak in DF decay kinetics probably depends on the rates of back reactions and possibly the organization of the thylakoid membrane (Desai et al, 1983). The exact physiological interpretation of transient peaks is quite difficult due to complex electron pathways and their interactions, however they appear to be formed when the metabolic conditions affect the redox status of Q A and Q B directly or indirectly.…”

“…A strong coupling of biochemical reactions in thylakoid membrane is also an essential prerequisite for hyperbolic decay. The transient peak is preferentially stimulated by far-red excitation (Desai et al, 1983;Hideg et al, 1991), but in some species it can also be induced by shorter wavelengths (Berden-Zrimec et al, 2008a;Zrimec et al, 2005) (Figure 3). In our experiments, Dunaliella tertiolecta Butcher (Chlorophyta) exhibited a peak at the illuminations below 600 nm and above 650 nm (Figure 3b), whereas Desmodesmus ( Scenedesmus) subspicatus Chodat 1926 (Chlorophyta) did not exhibit the peak at all (Berden- Zrimec et al, 2007).…”