A new mechanism for adaptation to changes in light intensity and quality in the red alga, Porphyra perforata. I. Relation to State 1—State 2 transitions

Satoh, Kazuhiko; Fork, David C.

doi:10.1016/0005-2728(83)90173-1

Cited by 51 publications

(46 citation statements)

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“…Therefore, this mechanism as well as the other mechanisms reported previously (5, 13,14) seem to be acting to prevent photoinhibition under natural conditions. It is possible that this acceleration of the back reaction is common to many plants although its effectiveness may differ between species.…”

Section: Discussionsupporting

confidence: 70%

“…However, in contrast to the data shown in Figure 2, it can be seen that the maximum fluorescence level was not noticeably decreased. Since there was no change in the levels of F., these data suggest that the fluorescence quenching was not caused by a decrease of light energy reaching PSII which may result from a state II to III transition (Satoh and Fork [13]). Rather, the decreased Fm level indicates that the quantum yield of the PSII reaction was decreased, which is compatible with the idea that the back reaction of PSII was accelerated by the light treatment.…”

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confidence: 85%

“…1) is produced by oxidation of Q by another mechanism different than oxidation via plastoquinone which is completely inhibited by DCMU at the concentration used. Fluorescence spectra at 77K before and after the quenching of the Chl fluorescence were the same suggesting that a change in transfer of light energy (state I-II transition or state 1I-state III transition [13,14]) was not the cause of this quenching (data not shown). Figure 3 shows the effects of NH20H, CCCP3, and antimycin A on the time course of fluorescence quenching.…”

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confidence: 90%

“…Fork and Oquist have reported (5) that the morphology of the pigment systems in Porphyra changed after air drying so that light energy absorbed by PSII was preferentially transferred to PSI. Recently, we found another mechanism in P. peforata that was termed state II-state III transitions (Satoh and Fork [13,14]). After a state II to III transition, the light energy reaching the reaction centers of PSII was decreased without any significant change in the PSI activity (Satoh and Fork [13]).…”

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confidence: 99%

“…Recently, we found another mechanism in P. peforata that was termed state II-state III transitions (Satoh and Fork [13,14]). After a state II to III transition, the light energy reaching the reaction centers of PSII was decreased without any significant change in the PSI activity (Satoh and Fork [13]). All these mechanisms may be useful to avoid the photoinhibition of photosynthesis in a plant such as Porphyra which is often exposed to high light intensity.…”

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A New Mechanism for Adaptation to Changes in Light Intensity and Quality in the Red Alga Porphyra perforata

Satoh

Fork²

1983

Plant Physiol.

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In the red alga Pwphyra perforata, the level of chlorophyll fluorescence in the presence of 3-(3,4-dichrophenyl)-1,1-dimethylurea (DCMU) decreased during illumination of the thaflus. The results showed that: (a) this decay was related to the photooxidative activity of photosystem I; (b) Q, the primary electron acceptor of photosystem II, became oxidize during the decay of the fluorescence; (c) reagents which inhibit the back reaction of photosystem II inhibited the decay.From these results, it is suggested that, when conditions in the chiloroplasts of this red alga become too oxidative, excess light energy can be converted to heat as a result of an accelerated back reaction ofphotosystem II. This may be one of the mechanisms by which this alga can cope with the high salt and high libt condiftons that can occur in its natural hatat.In the photosynthesis of red algae, two light-harvesting pigment proteins are involved. Phycobilisomes are mainly connected to PSII and most of Chl a belongs to PSI (11). To maintain a suitable ratio of activities of the two photosystems, red algae have evolved a mechanism to control the transfer of light energy from pigment system II to I, called state 12, 18). The red alga Porphyra perforata is an intertidal alga that is periodically exposed to high light and/or high salt conditions. Therefore, it might be expected that this alga has other mechanisms besides the state I-state II transitions to adapt it to live under high light conditions. Fork and Oquist have reported (5) that the morphology of the pigment systems in Porphyra changed after air drying so that light energy absorbed by PSII was preferentially transferred to PSI. Recently, we found another mechanism in P. peforata that was termed state II-state III transitions (Satoh and Fork [13,14]). After a state II to III transition, the light energy reaching the reaction centers of PSII was decreased without any significant change in the PSI activity (Satoh and Fork [13]). All these mechanisms may be useful to avoid the photoinhibition of photosynthesis in a plant such as Porphyra which is often exposed to high light intensity. However, in high salt concentrations where the water potential is very low, PSII activity would be expected to be strongly inhibited. Under these conditions, an additional mechanism(s) would be needed to avoid photodamage to this alga.In this study, we found in P. perforata a large light-induced fluorescence decrease in the presence of DCMU. It is proposed that this fluorescence decrease is related to one of the adaptation mechanisms of this alga to conditions of high light and low water potential. Fluorescence spectra at 77K and time courses at room temperature of fluorescence at 685 nm were measured using a fiber optic system to excite and collect the fluorescent light (6). PSI (433 nm) and PSII (550 nm) light, which are mainly absorbed by Chl a and phycoerythrin, respectively, were -obtained by passing the white light from a 150-w, 21.5-v projector lamp (type DLS) through Balzers interference filte...

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confidence: 70%

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confidence: 85%

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confidence: 90%

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confidence: 99%

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confidence: 99%

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