Photoinhibition and recovery in relation to heterogeneity of Photosystem II

Vanwijk, Kj; Schnettger, B.; Graf, Maria; Krause, G. Heinrich

doi:10.1016/0005-2728(93)90084-s

Cited by 22 publications

(4 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been suggested that the PQnonreducing centers are a subpopulation of PS IIβ centers. PS II centers differ also in antenna size, antenna protein composition (43), and susceptibility to photoinhibition (44).…”

Section: Resultsmentioning

confidence: 99%

Nonphotochemical Quenching of Excitation Energy in Photosystem II. A Picosecond Time-Resolved Study of the Low Yield of Chlorophyll a Fluorescence Induced by Single-Turnover Flash in Isolated Spinach Thylakoids

Васильев

Bruce

1998

Biochemistry

View full text Add to dashboard Cite

Chlorophyll a fluorescence emission is widely used as a noninvasive measure of a number of parameters related to photosynthetic efficiency in oxygenic photosynthetic organisms. The most important component for the estimation of photochemistry is the relative increase in fluorescence yield between dark-adapted samples which have a maximal capacity for photochemistry and a minimal fluorescence yield (F0) and light-saturated samples where photochemistry is saturated and fluorescence yield is maximal (Fm). However, when photosynthesis is saturated with a short (less than 50 micro(s)) flash of light, which induces only one photochemical turnover of photosystem II, the maximal fluorescence yield is significantly lower (Fsat) than when saturation is achieved with a millisecond duration multiturnover flash (Fm). To investigate the origins of the difference in fluorescence yield between these two conditions, our time-resolved fluorescence apparatus was modified to allow collection of picosecond time-resolved decay kinetics over a short time window immediately following a saturating single-turnover flash (Fsat) as well as after a multiturnover saturating pulse (Fm). Our data were analyzed with a global kinetic model based on an exciton radical pair equilibrium model for photosystem II. The difference between Fm and Fsat was modeled well by changing only the rate constant for quenching of excitation energy in the antenna of photosystem II. An antenna-based origin for the quenching was verified experimentally by the observation that addition of the antenna quencher 5-hydroxy-1,4-naphthoquinone to thylakoids under Fm conditions resulted in decay kinetics and modeled kinetic parameters very similar to those observed under Fsat conditions in the absence of added quinone. Our data strongly support the origin of low fluorescence yield at Fsat to be an antenna-based nonphotochemical quenching of excitation energy in photosystem II which has not usually been considered explicitly in calculations of photochemical and nonphotochemical quenching parameters. The implications of our data with respect to kinetic models for the excited-state dynamics of photosystem II and the practical applications of the fluorescence yield parameters Fm and Fsat to calculations of photochemical yield are discussed.

show abstract

Section: Resultsmentioning

confidence: 99%

Nonphotochemical Quenching of Excitation Energy in Photosystem II. A Picosecond Time-Resolved Study of the Low Yield of Chlorophyll a Fluorescence Induced by Single-Turnover Flash in Isolated Spinach Thylakoids

Васильев

Bruce

1998

Biochemistry

View full text Add to dashboard Cite

show abstract

“…Experiments using higher plants, algae, and cyanobacteria indicate that inactive PS II centers are a common feature of oxygenic organisms (Chylla et al 1987;Chylla and Whitmarsh 1989;Chylla and Whitmarsh 1990a,b;Graan and Ort 1986;Henrysson and Sundby 1990;Lavergne and Leci 1993;Melis 1985;Nedbal et al 1991;van Wijk et al 1993). In vivo measurements show that as much as one-third of the Photosystem II complexes in spinach leaves are inactive (Chylla and Whitmarsh 1989).…”

Section: Introductionmentioning

confidence: 99%

Light-dependent modification of Photosystem II in spinach leaves

et al. 1996

View full text Add to dashboard Cite

In dark-adapted spinach leaves approximately one third of the Photosystem II (PS II) reaction centers are impaired in their ability to transfer electrons to Photosystem I. Although these 'inactive' PS II centers are capable of reducing the primary quinone acceptor, QA, oxidation of QA (-) occurs approximately 1000 times more slowly than at 'active' centers. Previous studies based on dark-adapted leaves show that minimal energy transfer occurs from inactive centers to active centers, indicating that the quantum yield of photosynthesis could be significantly impaired by the presence of inactive centers. The objective of the work described here was to determine the performance of inactive PS II centers in light-adapted leaves. Measurements of PS II activity within leaves did not indicate any increase in the concentration of active PS II centers during light treatments between 10 s and 5 min, showing that inactive centers are not converted to active centers during light treatment. Light-induced modification of inactive PS II centers did occur, however, such that 75% of these centers were unable to sustain stable charge separation. In addition, the maximum yield of chlorophyll fluorescence associated with inactive PS II centers decreased substantially, despite the lack of any overall quenching of the maximum fluorescence yield. The effect of light treatment on inactive centers was reversed in the dark within 10-20 mins. These results indicate that illumination changes inactive PS II centers into a form that quenches fluorescence, but does not allow stable charge separation across the photosynthetic membrane. One possibility is that inactive centers are converted into centers that quench fluorescence by formation of a radical, such as reduced pheophytin or oxidized P680. Alternatively, it is possible that inactive PS II centers are modified such that absorbed excitation energy is dissipated thermally, through electron cycling at the reaction center.

show abstract

“…The ratio of Fv/Fm is known to be an excellent monitor of PS II photochemistry (Bjorkman 1987;Franklin et al 1992;van Wijk et al 1993). In the present investigation, the relaxation of fluorescence was observed to be fast and independent of the requirements for low light for the recovery from the damaging effects of high light on PS II.…”

Section: Discussionmentioning

confidence: 99%

Down regulation of photosynthesis in Artabotrys hexapetatus by high light

1995

View full text Add to dashboard Cite

Using variable to maximum fluorescence (Fv/Fm) as the criterion, the down regulation of photosynthesis by high light stress was characterized in the detached leaves of Artabotrys hexapetatus. The decrease in Fv/Fm was corelated with the decrease in oxygen evolution by thylakoids isolated from high light exposed leaves. The decrease in Fv/Fm was linear with increasing time of exposure to high light. A comparison of recovery measured as Fv/Fm, in low light versus dark, revealed that the recovery in darkness was as significant as in low light. Since the relaxation of fluorescence was a rapid response after exposure to high light and the fact that the recovery occurs in total darkness, it is concluded that photoinhibition and down regulation of photosynthesis by high light are independent events.

show abstract

Photoinhibition and recovery in relation to heterogeneity of Photosystem II

Cited by 22 publications

References 43 publications

Nonphotochemical Quenching of Excitation Energy in Photosystem II. A Picosecond Time-Resolved Study of the Low Yield of Chlorophyll a Fluorescence Induced by Single-Turnover Flash in Isolated Spinach Thylakoids

Nonphotochemical Quenching of Excitation Energy in Photosystem II. A Picosecond Time-Resolved Study of the Low Yield of Chlorophyll a Fluorescence Induced by Single-Turnover Flash in Isolated Spinach Thylakoids

Light-dependent modification of Photosystem II in spinach leaves

Down regulation of photosynthesis in Artabotrys hexapetatus by high light

Contact Info

Product

Resources

About