Two types of PS II centres as manifested by light saturation of delayed fluorescence from DCMU-treated chloroplasts

Vasil'ev, I.R.; Komarov, Andrey I.; Маторин, Д. Н.; Verkhoturov, Victor N.; Венедиктов, П.С.

doi:10.1007/bf00047081

Cited by 3 publications

(1 citation statement)

References 24 publications

(26 reference statements)

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“…It is also interesting to note that while a part of the fluorescence induction curve (without DCMU) can be explained by non-Qb reducing centres (Cao and Govinjee 1990), it also requires the assumption of two different kinds of Qb-reducing centres (Renger and Shulze 1985). Recently, two types of Photosystem II centre which did not correspond to the PSIIa/18 heterogeneity were identified by delayed fluorescence (Vasil'ev et al 1990). Indeed, one may expect more than two phases in fluorescence induction experiments in view of the existence of several types of heterogeneity (Black et al 1986, Govindjee 1991.…”

Section: Introductionmentioning

confidence: 99%

Analysis of fluorescence induction in thylakoids with the method of moments reveals two different active Photosystem II centres

Meunier

Bendall

1992

Photosynth Res

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There is presently a debate concerning the number of phases in fluorescence induction and on the identification of the several possible heterogeneities in PS II centres. However, the usual methods of analysis present numerical problems, including a lack of 'robustness' (robustness being defined as the ability to give the correct answer in the presence of distortions or artefacts). We present here the adaptation of the method of moments, which was developed for robustness, to the analysis of fluorescence induction. We were thus able to identify three phases in the fluorescence induction in the presence of DCMU. The slowest phase was attributed to the centres inactive in plastoquinone reduction by using duroquinone as electron acceptor. In order to compare fluorescence with and without DCMU, we introduced the 'rate of photochemistry', defined as the product of the area times the rate constant of an exponential. This quantity is invariant for a given centre no matter what the size of the electron acceptor pool is. The two fastest phases in the presence of DCMU were attributed to active centres because their rate of photochemistry was the same as that of the plastoquinone-reducing phases in the absence of DCMU. Because their reduction of plastoquinone showed different kinetics, these two types of active centres were either separated by more than 250 nm or were associated with discrete plastoquinone pools having restricted diffusion domains.

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Section: Introductionmentioning

confidence: 99%

Analysis of fluorescence induction in thylakoids with the method of moments reveals two different active Photosystem II centres

Meunier

Bendall

1992

Photosynth Res

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Analysis of high temperature stress on the dynamics of antenna size and reducing side heterogeneity of Photosystem II in wheat leaves (Triticum aestivum)

Mathur¹,

Allakhverdiev²,

Jajoo³

2011

Biochimica et Biophysica Acta (BBA) - Bioenergetics

131

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This study demonstrates the effect of high temperature stress on the heterogeneous behavior of PSII in Wheat (Triticum aestivum) leaves. Photosystem II in green plant chloroplasts displays heterogeneity both in the composition of its light harvesting antenna i.e. on the basis of antenna size (α, β and γ centers) and in the ability to reduce the plastoquinone pool i.e. the reducing side of the reaction centers (Q(B)-reducing centers and Q(B)-non-reducing centers). Detached wheat leaves were subjected to high temperature stress of 35°C, 40°C and 45°C. The chlorophyll a (Chl a) fluorescence transient were recorded in vivo with high time resolution and analyzed according to JIP test which can quantify PS II behavior using Plant efficiency analyzer (PEA). Other than PEA, Biolyzer HP-3 software was used to evaluate different types of heterogeneity in wheat leaves. The results revealed that at high temperature, there was a change in the relative amounts of PSII α, β and γ centers. As judged from the complementary area growth curve, it seemed that with increasing temperature the PSII(β) and PSII(γ) centers increased at the expense of PSII(α) centers. The reducing side heterogeneity was also affected as shown by an increase in the number of Q(B)-non-reducing centers at high temperatures. The reversibility of high temperature induced damage on PSII heterogeneity was also studied. Antenna size heterogeneity was recovered fully up to 40°C while reducing side heterogeneity showed partial recovery at 40°C. An irreversible damage to both the types of heterogeneity was observed at 45°C. The work is a significant contribution to understand the basic mechanism involved in the adaptation of crop plants to stress conditions.

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Alternative Measures of Photosystem Ii Electron Transfer Inhibition in Anthraquinone‐treated Chloroplasts

Karukstis

Moision

Johansen

et al. 1992

Photochem & Photobiology

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We have previously used chlorophyll fluorescence measurements at Fmax conditions (i.e. with Photosystem II electron acceptor QA reduced) to monitor the action of 9,10-anthraquinones on photosynthetic electron transport in plant chloroplasts. The present investigation employs two additional techniques to characterize the extent of electron transport inhibition induced by the addition of substituted anthraquinones to the suspending medium of spinach chloroplasts. Results are presented for spectrophotometric assays of the rate of electron transfer to an exogenous electron acceptor, 2,6-dichloroindophenol (DCIP) and for electrochemical determinations of the rate of oxygen evolution in anthraquinone-treated chloroplasts. In general, amino-substituted anthraquinones are ineffective inhibitors, maintaining electron transfer rates to DCIP at levels ranging from 50 to 90% of normal rates and yielding rates of O2 evolution averaging at 70% of the rate in untreated chloroplasts. In contrast, hydroxy-substituted anthraquinones efficiently block Photosystem II electron transport, resulting in low rates of DCIP photoreduction ranging from 0 to 20% of normal values and reducing O2 evolution rates to an average of 30% of the rate observed for untreated chloroplasts. Relative rates of DCIP photoreduction for anthraquinone-treated chloroplasts show a strong linear correlation with the reported relative Fmax chlorophyll fluorescence intensities. Relative O2 evolution rates are observed to correlate with the Stern-Volmer fluorescence quenching parameter Ksv. We suggest that slight differences in the extent of inhibitory activity of an anthraquinone as measured by the three techniques are consistent with certain known Photosystem II heterogeneities. The similarities in relative rankings of inhibitory effects for the 9, 10-anthraquinones, however, demonstrate that the three techniques employed (measurements of Fmax chlorophyll fluorescence, DCIP photoreduction rates, and O2 evolution rates) are alternative assays of anthraquinone-induced Photosystem II electron transport inhibition.

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Two types of PS II centres as manifested by light saturation of delayed fluorescence from DCMU-treated chloroplasts

Cited by 3 publications

References 24 publications

Analysis of fluorescence induction in thylakoids with the method of moments reveals two different active Photosystem II centres

Analysis of fluorescence induction in thylakoids with the method of moments reveals two different active Photosystem II centres

Analysis of high temperature stress on the dynamics of antenna size and reducing side heterogeneity of Photosystem II in wheat leaves (Triticum aestivum)

Alternative Measures of Photosystem Ii Electron Transfer Inhibition in Anthraquinone‐treated Chloroplasts

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