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Time sequence of the damage to the acceptor and donor sides of photosystem II by UV-B radiation as evaluated by chlorophyll a fluorescence.

van Rensen JJ, Vredenberg WJ, Rodrigues GC - Photosyn. Res. (2007)

Bottom Line: After the treatment with UV-B the damage was estimated using chlorophyll a fluorescence techniques.Measurements of modulated fluorescence using a pulse amplitude modulated fluorometer revealed that the efficiency of photosystem II decreased both with increasing time of UV-B radiation and with increasing intensity of the UV-B.Fluorescence induction rise curves were analyzed using a mechanistic model of energy trapping.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Plant Physiology, Wageningen University and Research Center, Arboretumlaan 4, Wageningen, 6703 BD, The Netherlands. Jack.VanRensen@wur.nl

ABSTRACT
The effects of ultraviolet-B (UV-B) radiation on photosystem II (PS II) were studied in leaves of Chenopodium album. After the treatment with UV-B the damage was estimated using chlorophyll a fluorescence techniques. Measurements of modulated fluorescence using a pulse amplitude modulated fluorometer revealed that the efficiency of photosystem II decreased both with increasing time of UV-B radiation and with increasing intensity of the UV-B. Fluorescence induction rise curves were analyzed using a mechanistic model of energy trapping. It appears that the damage by UV-B radiation occurs first at the acceptor side of photosystem II, and only later at the donor side.

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Effects of 6 h irradiation, at various levels, of detached leaves on some fluorescence parameters. CO is control; control is white light (PAR); UV-B is given by the Vilber lamp (zero PAR). Each value is the average of 4 measurements and the bars indicate ±S.D.; bars not shown are within the symbols
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Fig2: Effects of 6 h irradiation, at various levels, of detached leaves on some fluorescence parameters. CO is control; control is white light (PAR); UV-B is given by the Vilber lamp (zero PAR). Each value is the average of 4 measurements and the bars indicate ±S.D.; bars not shown are within the symbols

Mentions: Illumination with white light during 6 h decreased the photochemical quenching qP from 1.0 at the lowest intensity to a value of 0.58 at 656 μmol m−2 s−1 (Fig. 2). Curwiel et al. (1993), using the same plant material, reported a decrease to about 0.80 after illumination at about 500 μmol m−2 s−1. Up to 100 μmol m−2 s−1, irradiation with UV-B has a stronger effect on qP than white light; at 200 μmol m−2 s−1 and higher, the effect of UV-B is smaller. The efficiency of excitation energy capture by open PS II reaction centers, Fv′/Fm′, was already decreased strongly after 6 h at 5.4 μmol m−2 s−1 of UV-B, while the effect of white light is much smaller; comparable results were found for the quantum yield of PS II given by (Fm′ − Fs)/Fm′. The non-photochemical qN increased from 0 at the lowest intensities to 0.51 (white light) and 0.41 (UV-B) at the highest irradiation levels. Curwiel et al. (1993) reported a value of about 0.6 after illumination with white light at about 550 μmol m−2 s−1.Fig. 2


Time sequence of the damage to the acceptor and donor sides of photosystem II by UV-B radiation as evaluated by chlorophyll a fluorescence.

van Rensen JJ, Vredenberg WJ, Rodrigues GC - Photosyn. Res. (2007)

Effects of 6 h irradiation, at various levels, of detached leaves on some fluorescence parameters. CO is control; control is white light (PAR); UV-B is given by the Vilber lamp (zero PAR). Each value is the average of 4 measurements and the bars indicate ±S.D.; bars not shown are within the symbols
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2117334&req=5

Fig2: Effects of 6 h irradiation, at various levels, of detached leaves on some fluorescence parameters. CO is control; control is white light (PAR); UV-B is given by the Vilber lamp (zero PAR). Each value is the average of 4 measurements and the bars indicate ±S.D.; bars not shown are within the symbols
Mentions: Illumination with white light during 6 h decreased the photochemical quenching qP from 1.0 at the lowest intensity to a value of 0.58 at 656 μmol m−2 s−1 (Fig. 2). Curwiel et al. (1993), using the same plant material, reported a decrease to about 0.80 after illumination at about 500 μmol m−2 s−1. Up to 100 μmol m−2 s−1, irradiation with UV-B has a stronger effect on qP than white light; at 200 μmol m−2 s−1 and higher, the effect of UV-B is smaller. The efficiency of excitation energy capture by open PS II reaction centers, Fv′/Fm′, was already decreased strongly after 6 h at 5.4 μmol m−2 s−1 of UV-B, while the effect of white light is much smaller; comparable results were found for the quantum yield of PS II given by (Fm′ − Fs)/Fm′. The non-photochemical qN increased from 0 at the lowest intensities to 0.51 (white light) and 0.41 (UV-B) at the highest irradiation levels. Curwiel et al. (1993) reported a value of about 0.6 after illumination with white light at about 550 μmol m−2 s−1.Fig. 2

Bottom Line: After the treatment with UV-B the damage was estimated using chlorophyll a fluorescence techniques.Measurements of modulated fluorescence using a pulse amplitude modulated fluorometer revealed that the efficiency of photosystem II decreased both with increasing time of UV-B radiation and with increasing intensity of the UV-B.Fluorescence induction rise curves were analyzed using a mechanistic model of energy trapping.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Plant Physiology, Wageningen University and Research Center, Arboretumlaan 4, Wageningen, 6703 BD, The Netherlands. Jack.VanRensen@wur.nl

ABSTRACT
The effects of ultraviolet-B (UV-B) radiation on photosystem II (PS II) were studied in leaves of Chenopodium album. After the treatment with UV-B the damage was estimated using chlorophyll a fluorescence techniques. Measurements of modulated fluorescence using a pulse amplitude modulated fluorometer revealed that the efficiency of photosystem II decreased both with increasing time of UV-B radiation and with increasing intensity of the UV-B. Fluorescence induction rise curves were analyzed using a mechanistic model of energy trapping. It appears that the damage by UV-B radiation occurs first at the acceptor side of photosystem II, and only later at the donor side.

Show MeSH
Related in: MedlinePlus