The effects of ultraviolet irradiation on P680+ reduction in PS II core complexes measured for individual S-states and during repetitive cycling of the oxygen-evolving complex

Post, Adele; Lukins, P. B.; Walker, Peter; Larkum, A. W. D.

doi:10.1007/bf00029424

Cited by 26 publications

(11 citation statements)

References 25 publications

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“…Studies on a variety of plants have identified RUB-ISCO (Nogués andBaker 1995, Lesser 1996a, b) and the donor and/or acceptor side of PSII reaction centers (Post et al 1996, Vass et al 1996 as key photosynthetic targets. Especially significant for this work, Sagert et al (1997) demonstrated that the daily midday decline in efficiency of active PSII centers in upper and lower eulittoral populations of C. crispus was stimulated by the presence of natural UVR.…”

Section: Discussionmentioning

confidence: 99%

SYNTHESIS OF MYCOSPORINE‐LIKE AMINO ACIDS IN CHONDRUS CRISPUS (FLORIDEOPHYCEAE) AND THE CONSEQUENCES FOR SENSITIVITY TO ULTRAVIOLET B RADIATION

Franklin

Yakovleva

Karsten

et al. 1999

Journal of Phycology

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The induction and protective role of the UV-absorbing compounds known as mycosporine-like amino acids (MAAs) were examined in sublittoral Chondrus crispus Stackh. transplanted for 2 weeks in the spring and summer to shallow water under three irradiance conditions: PAR (photosynthetically active radiation; 400-700 nm), PAR ؉ UVA (PAR ؉ 320-400 nm), PAR ؉ UVA ؉ UVB (PAR ؉ UVA ؉ 280-320 nm). Sublittoral thalli collected around Helgoland, North Sea, Germany, from 6 m below the mean low water of spring tides contained less than 0.1 mg·g Ϫ1 dry weight (DW) total MAAs, whereas eulittoral samples contained over 1 mg·g Ϫ1 DW. Transplantation to shallow water led to the immediate synthesis of three MAAs in the following temporal order: shinorine ( max 334 nm), asterina ( max 330 nm), and palythine ( max 320 nm), with the shinorine content peaking and then declining after 2 days (exposure to 100 mol photons·m Ϫ2 ). Maximum total MAA content (2 mg·g Ϫ1 DW) also occurred after 2 days of induction, exceeding the content normally found in eulittoral samples. Furthermore, the relative proportion of the different MAAs at this time was different than that in eulittoral samples. After 2 days the total content declined to the eulittoral value, with palythine as the principal MAA. Similar data were obtained for all treatments, indicating that MAA synthesis in C. crispus was induced by PAR and not especially stimulated by UV radiation. The ability of photosystem II (PSII) to resist damage by UVB was tested periodically during the acclimation period by exposing samples to a defined UVB dose in the lab. Changes in chlorophyll fluorescence (F v /F m and effective quantum yield, II ) indicated that PSII function was inhibited during the initial stage of ac-1 climation but gradually improved with time. No difference among screening treatments was detected except in spring for the samples acclimating to PAR ؉ UVA ؉ UVB. In this treatment F v /F m and II were significantly lower than in the other treatments. During the first week of each experiment, growth rates were also significantly reduced by UVB. The reductions occurred despite maximum MAA content, indicating an incomplete protection of photosynthetic and growth-related processes. Abbreviations: chl, chlorophyll; F o , chlorophyll fluorescence of open PSII centers; F m , F v , maximum and variable chlorophyll fluorescence after dark incubation, respectively; F v /F m , optimal quantum yield; II , effective quantum yield in the light; MAA, mycosporine-like amino acid; MLWS, mean low water of spring tides; PSII, photosystem II; UVP, UVRabsorbing pigments; UVR, UV radiation

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Section: Discussionmentioning

confidence: 99%

SYNTHESIS OF MYCOSPORINE‐LIKE AMINO ACIDS IN CHONDRUS CRISPUS (FLORIDEOPHYCEAE) AND THE CONSEQUENCES FOR SENSITIVITY TO ULTRAVIOLET B RADIATION

Franklin

Yakovleva

Karsten

et al. 1999

Journal of Phycology

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“…Redox changes in the manganese cluster of such core complexes have been studied using UV difference absorption spectroscopy and ESR (van Leeuwen et al 1992(van Leeuwen et al , 1993. This work forms part of a broader investigation of the effects on PS II of ultraviolet radiation (Post et al 1996) and solvent interactions. It is also of considerable interest to compare these kinetics with those for PS II membrane fragment preparations such as BBY preparations in order to study the effects of differing interactions of extrinsic proteins and antennae molecules with the PS II reaction center for different preparations.…”

Section: Introductionmentioning

confidence: 99%

P680+ reduction in oxygen-evolving Photosystem II core complexes

et al. 1996

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The kinetics of P680(+) reduction in oxygen-evolving spinach Photosystem II (PS II) core particles were studied using both repetitive and single-flash 830 nm transient absorption. From measurements on samples in which PS II turnover is blocked, we estimate radical-pair lifetimes of 2 ns and 19 ns. Nanosecond single-flash measurements indicate decay times of 7 ns, 40 ns and 95 ns. Both the longer 40 ns and 95 ns components relate to the normal S-state controlled Yz → P680(+) electron transfer dynamics. Our analysis indicates the existence of a 7 ns component which provides evidence for an additional process associated with modified interactions involving the water-splitting catalytic site. Corresponding microsecond measurements show decay times of 4 μs and 90 μs with the possibility of a small component with a decay time of 20-40 μs. The precise origin of the 4 μs component remains uncertain but appears to be associated with the water-splitting center or its binding site while the 90 μs component is assigned to P680(+)-QA (-) recombination. An amplitude and kinetic analysis of the flash dependence data gives results that are consistent with the current model of the oxygen-evolving complex.

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“…The exact mechanism of UV-B radiation on PSII is still controversial. However, due to several studies with in vitro systems, there is a consensus that the donor side, most likely the Mn cluster of water oxidation, seems to be the major target site of UV-B damage (Renger et al 1989;Post et al 1996;Vass and Govindjee 1996). Beside damage to the water-oxidising complex, modification or damage at the accessory electron donor tyrosine of PSII (Y D ) and redox-active electron donor tyrosine of PSII (Y Z ) has also been observed (Yerkes et al 1990;.…”

Section: Introductionmentioning

confidence: 92%

Effects of UV irradiation on barley and tomato leaves: thermoluminescence as a method to screen the impact of UV radiation on crop plants

Gilbert

Skotnica

Weingart

et al. 2004

Functional Plant Biol.

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The effect of different UV intensities and irradiation times on barley and tomato leaves was investigated by analysis of thermoluminescence (TL) and chlorophyll (chl) fluorescence measurements. Epifluorescence microscopy was used to estimate the epidermal UV transmittance of leaves. In barley a strong supression of TL emission from the S 2 Q B − (B-band) and the S 2 Q A − (Q-band) charge recombination was observed, increasing with prolonged UV exposure. Primary barley leaves were more sensitive to UV than secondary leaves. In tomato plants a decrease in the B-band only takes place at very high UV intensities and after prolonged exposure times (4 h). The impact of UV in cotyledons was more pronounced than in pinnate leaves of tomato plants. The strong differences in sensitivity to UV in the investigated barley and tomato variety may be due to different concentrations of UV screening pigments in the epidermal layer as demonstrated by epifluorescence measurements. The results show that TL has the same potential to analyse the sensitivity or tolerance of crop plants to UV irradiation as routine fluorescence techniques. Furthermore, TL is directly monitoring the radical pair states of PSII and can distinguish between UV-induced donor and acceptor site-related damage.

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The effects of ultraviolet irradiation on P680+ reduction in PS II core complexes measured for individual S-states and during repetitive cycling of the oxygen-evolving complex

Cited by 26 publications

References 25 publications

SYNTHESIS OF MYCOSPORINE‐LIKE AMINO ACIDS IN CHONDRUS CRISPUS (FLORIDEOPHYCEAE) AND THE CONSEQUENCES FOR SENSITIVITY TO ULTRAVIOLET B RADIATION

SYNTHESIS OF MYCOSPORINE‐LIKE AMINO ACIDS IN CHONDRUS CRISPUS (FLORIDEOPHYCEAE) AND THE CONSEQUENCES FOR SENSITIVITY TO ULTRAVIOLET B RADIATION

P680+ reduction in oxygen-evolving Photosystem II core complexes

Effects of UV irradiation on barley and tomato leaves: thermoluminescence as a method to screen the impact of UV radiation on crop plants

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