Is the in vivo Photosystem I Function Resistant to Photoinhibition? An Answer from Photoacoustic and Far-Red Absorbance Measurements in Intact Leaves

Havaux, Michel; Eyletters, Murielle

doi:10.1515/znc-1991-11-1218

Cited by 29 publications

(12 citation statements)

References 9 publications

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“…High-light intensity is known to induce photoinhibition, that is, the energy dissipating mechanisms in competition with the radiative relaxation of Chl. The consequent reduction in ChlF was seen to be more marked on F685 than F735 (Agati 1998), in agreement with the greater resistance of PSI-as compared to PSII-to strong light stress (Havaux and Eyletters 1991) and with results from fluorescence measurements at 77 K (Demmig and Bjorkman 1987;Somersalo and Krause 1989). Photoinhibition at chilling temperatures was also observed to affect PSII, but not PSI, activity (Huang et al 2010).…”

Section: Discussionsupporting

confidence: 79%

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A retrieval algorithm to evaluate the Photosystem I and Photosystem II spectral contributions to leaf chlorophyll fluorescence at physiological temperatures

et al. 2011

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A new computational procedure to resolve the contribution of Photosystem I (PSI) and Photosystem II (PSII) to the leaf chlorophyll fluorescence emission spectra at room temperature has been developed. It is based on the Principal Component Analysis (PCA) of the leaf fluorescence emission spectra measured during the OI photochemical phase of fluorescence induction kinetics. During this phase, we can assume that only two spectral components are present, one of which is constant (PSI) and the other variable in intensity (PSII). Application of the PCA method to the measured fluorescence emission spectra of Ficus benjamina L. evidences that the temporal variation in the spectra can be ascribed to a single spectral component (the first principal component extracted by PCA), which can be considered to be a good approximation of the PSII fluorescence emission spectrum. The PSI fluorescence emission spectrum was deduced by difference between measured spectra and the first principal component. A single-band spectrum for the PSI fluorescence emission, peaked at about 735 nm, and a 2-band spectrum with maxima at 685 and 740 nm for the PSII were obtained. A linear combination of only these two spectral shapes produced a good fit for any measured emission spectrum of the leaf under investigation and can be used to obtain the fluorescence emission contributions of photosystems under different conditions. With the use of our approach, the dynamics of energy distribution between the two photosystems, such as state transition, can be monitored in vivo, directly at physiological temperatures. Separation of the PSI and PSII emission components can improve the understanding of the fluorescence signal changes induced by environmental factors or stress conditions on plants.

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Section: Discussionsupporting

confidence: 79%

“…PSI seems to be much less sensitive to photochemistry (Krause and Weis 1991) and more resistant than PSII to strong light stress (Havaux and Eyletters 1991). Therefore, any change in the above quenching parameters should be reflected in a change in the Chl F685/F735.…”

Section: Introductionmentioning

confidence: 99%

A retrieval algorithm to evaluate the Photosystem I and Photosystem II spectral contributions to leaf chlorophyll fluorescence at physiological temperatures

et al. 2011

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“…Nevertheless, from a qualitative point of view, the closure of the PSI centers during heat stress in the dark could be interpreted as the adjustment of the PSI photochemical efficiency to the decreased rate of photochemistry in PSII. Interestingly, a relationship between Bx and V similar to that observed during heat stress in the dark was measured after a photoinhibitory treatment affecting specifically PSII (Havaux and Eyletters 1991). Overall, it can be concluded that short exposures of intact pea leaves to high temperature affected both PSI and PSII.…”

Section: P68o~ --P68osupporting

confidence: 65%

Functioning of photosystems I and II in pea leaves exposed to heat stress in the presence or absence of light

Havaux

Greppin

Strasser

1991

Planta

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198

111

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Fluorimetric, photoacoustic, polarographic and absorbance techniques were used to measure in situ various functional aspects of the photochemical apparatus of photosynthesis in intact pea leaves (Pisum sativum L.) after short exposures to a high temperature of 40 ° C. The results indicated (i) that the in-vivo responses of the two photosystems to high-temperature pretreatments were markedly different and in some respects opposite, with photosystem (PS) II activity being inhibited (or down-regulated) and PSI function being stimulated; and (ii) that light strongly interacts with the response of the photosystems, acting as an efficient protector of the photochemical activity against its inactivation by heat. When imposed in the dark, heat provoked a drastic inhibition of photosynthetic oxygen evolution and photochemical energy storage, correlated with a marked loss of variable PSII-chlorophyll fluorescence emission. None of the above changes were observed in leaves which were illuminated during heating. This photoprotection was saturated at rather low light fluence rates (around 10 W · m(-2)). Heat stress in darkness appeared to increase the capacity for cyclic electron flow around PSI, as indicated by the enhanced photochemical energy storage in far-red light and the faster decay of P 700 (+) (oxidized reaction center of PSI) monitored upon sudded interruption of the far-red light. The presence of light during heat stress reduced somewhat this PSI-driven cyclic electron transport. It was also observed that heat stress in darkness resulted in the progressive closure of the PSI reaction centers in leaves under steady illumination whereas PSII traps remained largely open, possibly reflecting the adjustment of the photochemical efficiency of undamaged PSI to the reduced rate of photochemistry in PSII.

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“…Cyclic electron flow through PSI may act to maintain a strong transthylakoid proton gradient and high thermal de-excitation at PS II under such conditions of severe photoinhibition. PSI is known to be much more resistant to photoinhibition than is PS II (Canaani et al 1989, Havaux and Eyletters 1991). Further, Topf et al (1992 have observed that photoinhibition of PS II in Chlamydomonas causes a stimulation of cyclic electron flow through PSI that in turn functions to maintain the transthylakoid proton gradient in photoinhibited cells.…”

Section: Regulation Of Photosystem Hmentioning

confidence: 99%

Electron transport and photophosphorylation by Photosystem I in vivo in plants and cyanobacteria

1993

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Recently, a number of techniques, some of them relatively new and many often used in combination, have given a clearer picture of the dynamic role of electron transport in Photosystem I of photosynthesis and of coupled cyclic photophosphorylation. For example, the photoacoustic technique has detected cyclic electron transport in vivo in all the major algal groups and in leaves of higher plants. Spectroscopic measurements of the Photosystem I reaction center and of the changes in light scattering associated with thylakoid membrane energization also indicate that cyclic photophosphorylation occurs in living plants and cyanobacteria, particularly under stressful conditions.In cyanobacteria, the path of cyclic electron transport has recently been proposed to include an NAD(P)H dehydrogenase, a complex that may also participate in respiratory electron transport. Photosynthesis and respiration may share common electron carriers in eukaryotes also. Chlororespiration, the uptake of O2 in the dark by chloroplasts, is inhibited by excitation of Photosystem I, which diverts electrons away from the chlororespiratory chain into the photosynthetic electron transport chain. Chlororespiration in N-starved Chlamydomonas increases ten fold over that of the control, perhaps because carbohydrates and NAD(P)H are oxidized and ATP produced by this process.The regulation of energy distribution to the photosystems and of cyclic and non-cyclic phosphorylation via state 1 to state 2 transitions may involve the cytochrome b 6-f complex. An increased demand for ATP lowers the transthylakoid pH gradient, activates the b 6-f complex, stimulates phosphorylation of the light-harvesting chlorophyll-protein complex of Photosystem II and decreases energy input to Photosystem II upon induction of state 2. The resulting increase in the absorption by Photosystem I favors cyclic electron flow and ATP production over linear electron flow to NADP and 'poises' the system by slowing down the flow of electrons originating in Photosystem II.Cyclic electron transport may function to prevent photoinhibition to the photosynthetic apparatus as well as to provide ATP. Thus, under high light intensities where CO2 can limit photosynthesis, especially when stomates are closed as a result of water stress, the proton gradient established by coupled cyclic electron transport can prevent over-reduction of the electron transport system by increasing thermal de-excitation in Photosystem II (Weis and Berry 1987). Increased cyclic photophosphorylation may also serve to drive ion uptake in nutrient-deprived cells or ion export in salt-stressed cells.There is evidence in some plants for a specialization of Photosystem I. For example, in the red alga Porphyra about one third of the total Photosystem I units are engaged in linear electron transfer from Photosystem II and the remaining two thirds of the Photosystem I units are specialized for cyclic electron flow. Other organisms show evidence of similar specialization.Improved understanding of the biological role of cyclic pho...

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Is the in vivo Photosystem I Function Resistant to Photoinhibition? An Answer from Photoacoustic and Far-Red Absorbance Measurements in Intact Leaves

Cited by 29 publications

References 9 publications

A retrieval algorithm to evaluate the Photosystem I and Photosystem II spectral contributions to leaf chlorophyll fluorescence at physiological temperatures

A retrieval algorithm to evaluate the Photosystem I and Photosystem II spectral contributions to leaf chlorophyll fluorescence at physiological temperatures

Functioning of photosystems I and II in pea leaves exposed to heat stress in the presence or absence of light

Electron transport and photophosphorylation by Photosystem I in vivo in plants and cyanobacteria

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