Salt Enhances Photosystem I Content and Cyclic Electron Flow via NAD(P)H Dehydrogenase in the Halotolerant Cyanobacterium Aphanothece halophytica

Hibino, Takashi; Bh, Lee; Kumar, Awani; Ishikawa, Hiroshi; Kojima, Hisashi; Tawada, M; Shimoyama, Hiromitsu; Takabe, Teruhiro

doi:10.1071/pp9960321

Cited by 43 publications

(31 citation statements)

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“…PCC 6803; Erdmann et al 1992), extrusion of Na + from the cell Fry et al 1986; Molitor et al 1986), or sequestering such ions into vacuoles (Munns 1993 and references therein). This energy appears to be provided by increased cyclic electron transport around PSI (Fork and Herbert 1993;Jeanjean et al 1993;Hibino et al 1996;Joset et al 1996;Tanaka et al 1997) and by increased respiratory electron transport (Fry et al 1986;Molitor et al 1986;Moser et al 1991;Jeanjean et al 1993).…”

Section: Introductionmentioning

confidence: 92%

A strain of Synechocystis sp. PCC 6803 without photosynthetic oxygen evolution and respiratory oxygen consumption: implications for the study of cyclic photosynthetic electron transport

Howitt

Cooley

Wiskich

et al. 2001

Planta

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Cyclic electron transport around photosystem (PS) I is believed to play a role in generation of ATP required for adaptation to stress in cyanobacteria and plants. However, elucidation of the pathway(s) of cyclic electron flow is difficult because of low rates of this electron flow relative to those of linear photosynthetic and respiratory electron transport. We have constructed a strain of Synechocystis sp. PCC 6803 that lacks both PSII and respiratory oxidases and that, consequently, neither evolves nor consumes oxygen. However, this strain is still capable of cyclic electron flow around PSI. The photoheterotrophic growth rate of this strain increased with light intensity up to an intensity of about 25 mumol photons m-2 s-1, supporting the notion that cyclic electron flow contributes to ATP generation in this strain. Indeed, the ATP-generating ability of PSI is demonstrated by the fact that the PSII-less oxidase-less strain is able to grow at much higher salt concentrations than a strain lacking PSI. A quinone electrode was used to measure the redox state of the plastoquinone pool in vivo in the various strains used in this study. In contrast to what is observed in chloroplasts, the plastoquinone pool was rather reduced in darkness and was oxidized in the light. This is in line with significant electron donation by respiratory pathways (NADPH dehydrogenase and particularly succinate dehydrogenase) in darkness. In the light, the pool becomes oxidized due to the presence of much more PSI than PSII. In the oxidase-less strains, the plastoquinone pool was very much reduced in darkness and was oxidized in the light by PSI. Photosystem II activity did not greatly alter the redox state of the plastoquinone pool. The results suggest that cyclic electron flow around PSI can contribute to generation of ATP, and a strain deficient in linear electron transport pathways provides an excellent model for further investigations of cyclic electron flow.

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Section: Introductionmentioning

confidence: 92%

A strain of Synechocystis sp. PCC 6803 without photosynthetic oxygen evolution and respiratory oxygen consumption: implications for the study of cyclic photosynthetic electron transport

Howitt

Cooley

Wiskich

et al. 2001

Planta

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“…Enhancement in PSI activity should increase cyclic electron transport. Several reports have shown that cyclic electron flow increases under salinity stress (Jeanjean et al, 1993 ;Hibino et al, 1996). Thus, it seems that an increase in PSI activity in salt-adapted cells could protect PSII from excessive excitation energy under salt stress.…”

Section: mentioning

confidence: 99%

Characterization of PSII photochemistry in salt‐adapted cells of cyanobacterium Spirulina platensis

Vonshak

1999

New Phytologist

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The changes in pigment composition, photosynthesis and PSII photochemistry were investigated in cells of Spirulina platensis adapted to salt stress ( 0n75 M NaCl). A decrease in the phycocyanine\chlorophyll and no significant change in the carotenoid\chlorophyll ratio were observed in salt-adapted cells. Salt stress inhibited the apparent quantum efficiency of photosynthesis and PSII activity while stimulating PSI activity and dark respiration significantly. Salt stress also resulted in a decrease in overall activity of the electron transport chain, which could not be restored by diphenylcarbazide, an artificial electron donor to the reaction centres of PSII. Measurements of the polyphasic fluorescence rise in fluorescence transients including phases O, J, I and P showed that salt stress had no effect on the fluorescence yield at phase O but decreased the fluorescence yield at phases J, I and P. Analyses of the JIP test developed from the polyphasic rise of fluorescence transients showed that salt stress led to a decrease in both the maximum quantum efficiency of PSII photochemistry and the maximum quantum efficiency of electron transport beyond the primary quinone electron acceptor. However, salt stress induced no significant changes in the probability of transporting an electron beyond Q A , the trapping flux per PSII reaction centre, or the electron transport flux per PSII reaction centre. A theoretical analysis of fluorescence parameters indicated a decrease in the rate constant of excitation energy trapping by PSII reaction centres. In addition, salt stress induced an increase in the complementary area above the fluorescence induction curve in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea, suggesting an increase in the proportion of closed PSII reaction centres in salt-adapted cells. Based on these results, it is suggested that modifications in PSII photochemistry in salt-adapted Spirulina cells maintained a high conversion efficiency of excitation energy, such that no significant change was observed in either the trapping flux or the electron transport flux per PSII reaction centre.

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“…Secondly, there is the increased rate of respiration in the dark in Aphanizomenon. It has been shown that an increase in cyclic electron transport, facilitated by the increase in PSI content, coincides with a concerted change in cyanobacterial respiration (Jeanjean et al, 1993 ;Hibino et al, 1996). Thirdly, there is in Aphanizomenon, a more pronounced decrease in photon yield during the dark period.…”

Section: Light-limited Growth Of Diazotrophsmentioning

confidence: 99%

Comparison of the light‐limited growth of the nitrogen‐fixing cyanobacteria Anabaena and Aphanizomenon

et al. 1998

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The effect of simultaneous N # fixation and light limitation on the growth of two strains of Anabaena sp. Bory de St. Vincent and Aphanizomenon flos-aquae (L.) Ralfs was investigated using continuous cultures. Under severely light-limited conditions, Aphanizomenon showed a broader absorption spectrum (due to the presence of phycoerythrin), a higher maximum efficiency of photosynthesis, a higher steady-state N # fixation activity and a higher growth affinity for light than did Anabaena. On the other hand, under light saturation, Anabaena showed a higher maximum rate of O # production and a higher maximum specific growth rate than Aphanizomenon. These monoculture results characterize Anabaena and Aphanizomenon, in relative terms, as a ' sun ' and a ' shade ' species respectively, and are in accordance with field observations. The difference between the two species in their acclimatory response is discussed in terms of a species-specific alteration of the PSI : PSII stoichiometry. Besides the species-specific modulation of the accessory pigments, such an acclimation would provide a biochemical basis for the observed physiological differences. The monoculture results were used to differentiate the niches of the two species and suggested that Aphanizomenon would competitively displace Anabaena under N # -fixing, light-limited conditions. However, when both species were grown together, Anabaena became dominant and seemed to be the superior competitor for light. In order to explain this finding, the possible effects of release of allelopathic compounds, or dynamic aspects of light supply, are discussed.

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Salt Enhances Photosystem I Content and Cyclic Electron Flow via NAD(P)H Dehydrogenase in the Halotolerant Cyanobacterium Aphanothece halophytica

Cited by 43 publications

References 0 publications

A strain of Synechocystis sp. PCC 6803 without photosynthetic oxygen evolution and respiratory oxygen consumption: implications for the study of cyclic photosynthetic electron transport

A strain of Synechocystis sp. PCC 6803 without photosynthetic oxygen evolution and respiratory oxygen consumption: implications for the study of cyclic photosynthetic electron transport

Characterization of PSII photochemistry in salt‐adapted cells of cyanobacterium Spirulina platensis

Comparison of the light‐limited growth of the nitrogen‐fixing cyanobacteria Anabaena and Aphanizomenon

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