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Productional Biology: Kinetic Imaging of Plant Chlorophyll Fluorescence Ladislav Nedbal modified by M. Bartak
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Early Fluorescence Imaging Experiment Kautsky and Hirsch (1931) irradiated a dark-adapted leaf with a blue light and observed it visually through a dark-red glass. Here is a high-tech presentation of what they saw: Bio-Sphere2, Tuscon AZ, Nov.29, 2001
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Chlorophyll a fluorescence competes with photosynthesis for excitation energy S0S0 S1S1 S2S2 Chla h blue photosynthesis Fluorescence h NIR Heat
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Role #1 of light in plant fluorescence experiments – measuring light S0S0 S1S1 S2S2 Chla photosynthesis Fluorescence h NIR Aim: Excite the fluorescence- emitting pigment molecules without changing the experimental photo- chemically active object. Fluorescence should be distinguishable from background of the same color. Achieved by MEASURING light: Typically 10-30 s long flashes repeated with a low frequency that = max F 0 =F min
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Role #2 of light in plant fluorescence experiments – actinic light S0S0 S1S1 S2S2 Chla photosynthesis Fluorescence h NIR Aim: Excite the fluorescence- emitting pigment molecules without changing the experimental photo- chemically active object. Fluorescence should be distinguishable from background of the same color. Achieved by MEASURING light: Typically 10-30 s long flashes repeated with a low frequency that = (t) F =F (t)
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Role #3 of light in plant fluorescence experiments – saturating light S0S0 S1S1 S2S2 Chla photosynthesis Fluorescence h NIR Aim: Excite the fluorescence- emitting pigment molecules without changing the experimental photo- chemically active object. Fluorescence should be distinguishable from background of the same color. Achieved by MEASURING light: Typically 10-30 s long flashes repeated with a low frequency that = F =F max
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Fluorescence QA-QA- 750 LED’s are on for 10-200 s Only few PSII RC’s are excited Yet, sufficient fluorescence emission is produced to capture an image Measuring flashes have little actinic effects
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QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- During the actinic light exposure, the continuous excitation keeps some of the PSII RC’s closed LEDs are on for seconds to minutes Actinic light is causing fluorescence induction
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F0F0 F PEAK from F 0 with open PSII RC’s to F PEAK with mostly closed PSII RC’s In fluorescence, the actinic light elicits in plants the Kautsky effect of fluorescence induction. QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- Actinic light is causing fluorescence induction
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Induction in a diuron-inhibited leaf DCMU
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Before the pulse During the pulse, PSII RC’s are closed by a transient reduction of the plastoquinone pool. The shutter of the halogen lamp is open typically for 1s QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- PQ-reducing super pulse Bio-Sphere2, Tuscon AZ, Nov.29, 2001
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Fluorescence before the pulse F0F0 Open PSII reaction centers The closure of all PS RC’s is reflected by a transient from F 0 to F M. Fluorescence at the end of the pulseFMFM QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- QA-QA- Fluorescence in PQ-reducing saturation pulse.
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F0F0 FMFM FVFV FSFS FM’FM’ Pixel-to-pixel arithmetic image operations
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„Cyanobacterial“ Chl fluorescence kinetics Source: http://www.sciencedirect.com/science/article/pii/S0014579304014991
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Campbell D et al. Microbiol. Mol. Biol. Rev. 1998;62:667-683 Fluorescence emission trace for cyanobacterial quenching analysis. F0F0 FMFM FVFV FSFS FM’FM’
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Color photograph Fluorescence F M image Chlorophyll fluorescence from ripe lemon fruits
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Color photograph Fluorescence images F0F0 FVFV FMFM F V /F M Heterogeneous lemon pigmentation
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Color photograph Fluorescence images F0F0 FMFM F V /F M FVFV Post-harvest lemon damage
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Phytotoxin response visualized by fluorescence Sinapis alba 60 h, 2000 mg/l destruxin Brassica oleracea 60 h, 0-500 mg/l destruxin 0.05 mg/l 0 mg/l 0.5mg/l 50mg/l 500mg/l
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Mutant selection
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High-light stress sensitivity F V /F M 2
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Field operation
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50 m F V / F M FSFS F S – F 0 Microscopic kinetic fluorescence imaging diatoms Elodea chloroplasts Average Bio-Sphere2, Tuscon AZ, Nov.29, 2001
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