Fluorescence induction kinetics

Figure 4 (left panels) shows light-induced fluorescence induction kinetics, the variable part of which reflects the photoreduction of QA in the thylakoid membranes of control and the Chi Mess mutant [Melis and Duysens 1979]. The fluorescence induction kinetics of the control strain were faster than that of the Chi Mess mutant, suggesting a larger PSII Chi antenna size for the former. 

Left panels Chi fluorescence induction kinetics of control (upper) and a Chi i-less mutant (lower). Right panels Corresponding semilogarithmic plots of the area over the fluorescence induction curve. 

C. Biichel, C. Wilhelm (1993). In vivo analysis of slow chlorophyll fluorescence induction kinetics in algae progress, problems and perspectives. Photochem. Photobiol., 58,137-148. 

Fluorescence induction kinetics of leaves is more complex as compared to chloroplasts since it depends significantly on the state of the photosynthetic apparatus, determined by duration and intensity of illumination, composition of the gas phase etc. (8,9). Probably, dark relaxation kinetics of leaves may be also more complicaf-ted and the study of this phenomenon allows to follow the processes contributing in Q reoxidation. This work was aimed at elucidation of the pathways of electron efflux from Q after switching off the actinic light on leaves. 

It has been shown in these proceedings (see Schwarz und Strasser) that the capacity for variable fluorescence can be regenerated in the dark at 77K up to 100%. The regeneration is highly biphasic with a plateau at a dark time between two illuminations of ca 30 minutes and ca 3 days. Admitting the electron flow scheme from the reaction center P to and to Qg (indicated here in alphabetical order P.Q.R) explains the four fluorescence induction kinetics at 77K and at room temperature of leaves under physiological conditions. They are shown in Table 1 and presented with experimental data in these proceedings (2) and (3). 

We simultaneously measured the oxygen evolution and fluorescence induction kinetics of green algae. The experimental results are compared with computer simulations. 

In the PPFD range of 0-500 pmol m" s the R2K1 mutant appears to be somewhat less sensitive to photoinhibition than do the other mutant R2S2C3 and the wild type R2 (Table 1). This is shown both by the 77K fluorescence induction kinetics data O2 evolution measured as pmol Or... 

To study the PSII antenna heterogeneity the fluorescence induction kinetics of isolated thylakoids was monitored in the presence of 20 ]M DCNU. Bmax value representing the percentage of PSIIB centers was calculated from biphasic... 

Fluorescence induction kinetics was measured at room temperature with a modified Aminco spectrophotometer in the presence of 20 mM DCMU after 5 min of dark adaptation. Relative rate of pheophytin anion photoaccumulation in PSII was estimated from the analysis of the fluorescence quenching curve in the presence of 20 mM dithionite (in 50mM Tricine, pH 7.8). 

Of the first 31 chlorina mutants characterised in the Copenhagen mutant collection, 9 were found to be characterised by unusually high F680/F740 and Fm/Fo ratios, when examined by low temperature fluorescence emission spectroscopy and room temperature fluorescence induction kinetics (1). Of these nine, four showed these properties when grown in the glasshouse at 17°C, but not at 22°C. This paper describes one of these temperature-sensitive mutants, chlorina- y which is the first barley mutant in which mutant leaf tissue returns to normal as the result of being shifted from the restrictive temperature. 

Analysis of the data shows some mutants to be blocked in PS-II (/ic/103mu, 103, 114), others blocked in the cytochrome bg/f complex hcf 102, 105, 109, 110, 111), and another class blocked in PS-I hcf 101, 104). Upon further analysis mutants hcf 107 and 108 showed a reduction of the proton translocating ATPase CFi, while the two remaining mutants were not clearly defined. Analysis of leaf fluorescence induction kinetics (Kautsky effect) supported the above characterization of the mutants. 

FROST RESISTANCE OF WHEAT AND CHL a IN VIVO FLUORESCENCE INDUCTION KINETICS... 

Fig 1. Comparison of Chlorophyll fluorescence induction kinetics curves of 6 wheat Cultivars (W-1...W-6) in the order of decreasing frost resistance. Each curve was plotted after accumulation and average from 10 measurements. 3 leaf sections for one measurement. 

Typical fluorescence induction kinetics curves of 6 cultivars are recorded in March (Fig 1) when the hardening is completed and the average temperature is just above O C. Some parameters of 6 cultivars are calculated from Fig 1 by the computer and plotted in Fig 2. 

In this report we have examined the effect of high temperature on the fluorescence induction kinetics of attached wheat leaves. In addition/ we have also studied the extent of recovery of the... 

Fig. 4 Room temperature fluorescence induction kinetics of dark adapted intact wheat leaves after different times of recovery in dark at room temperature subsequent to heat shock at different temperatures for 30 minutes.

To evaluate the photosystem 2 (PS2) activity the parameters Fg and Fy of prompt fluorescence induction kinetics of leaf discs and isolated chloroplasts were measured with chlorophyll fluorescence measuring system, PAM (15). The chloroplasts were diluted with 10 mM Tricine buffer, pH 7.8, containing 330 mM sorbitol, 5 mM MgSOd and 1.6 mM of corresponding PA to 60 pg/ml. The leaf discs were incubated 1h in... 

The incubation of photosynthetic objects at high temperatures led to their inactivation, expressed also as changes in the pattern of the prompt fluorescence induction kinetics - Fq increase and a reciprocal decrease in Fy (17). PAs treatment of the investigated objects did not change the course of Fq temperature dependence, but considerably influenced Fy. The curve of high temperature inactivation of the ratio Fy/Fo Uhis parameter was the most sensitive to temperature action) was sigmoidal and the temperature of 50% inhibition (T50) indicated the thermostability of the object (Figs. 1,2). 

By measuring the chlorophyll fluorescence induction kinetics and the fluorescence spectrum of an intact leaf or plant the condition and potential activity of the photosynthetic apparatus can be estimated (1, ed. H.K. Lichtenthaler). Solely two parameters namely the chlorophyll fluorescence ratio F685/F730 and the fluorescence life time are reliable to measure by remote sensing (2). 

Frost Resistance of Wheat and CHL a in vivo Fluorescence Induction Kinetics 647... 

The characteristics of the wild type of C. reinhardtii, of the high fluorescent mutant F I 39 and of the low fluorescent mutants mf I mf 2 and mf 3 have been indicated (10, 11). Algae were grown in light, in Tris-acetate medium (12). Lipids and chlorophyll-protein complexes were analyzed as previously described (9). The fluorescence induction kinetics and the low temperature emission spectra of whole cells were measured as in (9). 

The fluorescence induction kinetics and the low-temperature (77 K) fluorescence spectra of the mutant were indistinguishable from the wild type (McCourt et al., 1985). 

Figure 1. Chlorophyll fluorescence Induction kinetics for intact cells. Bar equals 1 min. Cell concentration normalized to 10 cells per ml.

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