Fluorescence emission spectra of Photosystem I, Photosystem II and the light-harvesting chlorophyll a/b complex of higher plants

1977 ◽  
Vol 462 (2) ◽  
pp. 307-313 ◽  
Author(s):  
Reto J. Strasser ◽  
Warren L. Butler
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Light Harvesting ◽  
Higher Plants ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Fluorescence Emission Spectra

Changes of the Photosynthetic Apparatus in Spirulina Cyanobacterium by Sodium Stress

2000 ◽  
Vol 55 (1-2) ◽  
pp. 16-22 ◽  
Author(s):  
Kavita Verma ◽  
Prasanna Mohanty
Keyword(s):  
Chlorophyll A ◽  
Photosystem I ◽  
Protein Interactions ◽  
Room Temperature ◽  
Photosynthetic Apparatus ◽  
Fluorescence Emission ◽  
Emission Spectra ◽  
Energy Harvest ◽  
Fluorescence Emission Spectra ◽  
Transfer Processes

Abstract Spirulina platensis trichomes grown in Zarrouks medium having total Na+ concentration as 0.14 ᴍ when transfered to fresh Zarrouks medium containing enhanced level of Na+ ions equal to 0.86 ᴍ showed 30% more accumulation of Na+ intracellularly as compared to the control. An inhibition of photosystem II activity to almost 66% was observed. Also due to this exposure to high Na+, the room temperature absorption characteristics of Spirulina trichomes and the thylakoid membrane preparations w ere altered indicating changes in the chromophore protein interactions and alterations in the phycocyanin/allophycocyanin ratio; there by affecting the energy harvest and energy transfer processes. An increase in the carotenoid absorption was two fold over the control in the treated sample. Similarly, room temperature and low temperature (77 K) fluorescence emission spectra collectively suggested alterations in the chlorophyll a emissions, F 726 of photosystem I reflecting changes in the lipid protein environment of the thylakoid. Our results indicate that in Spirulina the enhanced Na+ level alters the energy harvest and transfer processes. It also affected the emission characteristics of chlorophyll a of photosystem I.

Relationship between Changes in Ion Content of Leaves and Chlorophyll-Protein Composition in Cucumber under Cd and Pb Stress

1999 ◽  
Vol 54 (9-10) ◽  
pp. 746-753 ◽  
Author(s):  
Éva Sárvári ◽  
Ferenc Fodor ◽  
Edit Cseh ◽  
Anita Varga ◽  
Gyula Záray ◽  
...  
Keyword(s):  
Chlorophyll Content ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Light Harvesting ◽  
Fluorescence Emission ◽  
Light Harvesting Complex ◽  
Complex Ii ◽  
Iron Deficient ◽  
Light Harvesting Complex Ii ◽  
Chlorophyll Protein

Hydroponically cultured cucumber plants supplied with 4 μᴍ Fe chelated either with EDTA or citrate and treated with Cd (10 μᴍ) and Pb (10, 50 μᴍ) from their one- or fourleaf stage were grown up to five-week-old age. The decrease in the chlorophyll content was the most pronounced in plants treated with Cd from a younger age, and in the case of Fecitrate. The chlorophyll a/b ratio of Cd stressed plants was also significantly lowered. In later treated plants the accumulation of chlorophyll was inhibited and the chlorophyll a/b ratio decreased only in the vigorously growing young leaves. Pb treatment had only a slight effect on both parameters. The changes in the chlorophyll-protein pattern of thylakoids were strongly related to their chlorophyll content but the response of each complex was different. Cd reduced the amount of chlorophyll containing complexes in the order of photosystem I > light-harvesting complex II > photosystem Il-core, while light-harvesting complex II appeared somewhat more sensitive than photosystem I in Pb treated plants. In accordance, a decline or blue shift of the long wavelength fluorescence emission band of chloroplasts was observed referring to disturbances also in photosystem I antenna assembly. The accumulation of chlorophyll and chlorophyll-proteins did not show close relationship to the heavy metal content of leaves which was the highest in the first of the intensively expanding leaves in the time of the treatment. The extraordinary sensitivity of photosystem I, and the relative stability of photosystem II under Cd treatment were similar to the case found in iron deficient plants. However, the pattern of chlorophyll content of leaf storeys of Cd treated plants rather followed the changes in their Mn content

STRUCTURAL RELATIONSHIPS OF THE PHOTOSYSTEM I AND PHOTOSYSTEM II CHLOROPHYLL a/b AND a/c LIGHT-HARVESTING APOPROTEINS OF PLANTS AND ALGAE

1993 ◽  
Vol 57 (1) ◽  
pp. 143-151 ◽  
Author(s):  
F. Gerald Plumley ◽  
Tracey A. Martinson ◽  
David L. Herrin ◽  
Masahiko Ikeuchi ◽  
Gregory W. Schmidt
Keyword(s):  
Photosystem Ii ◽  
Chlorophyll A ◽  
Photosystem I ◽  
Light Harvesting ◽  
Structural Relationships

scholarly journals Photosynthetic light harvesting and thylakoid organization in a CRISPR/Cas9 Arabidopsis thaliana LHCB1 knockout mutant.

2021 ◽  
Author(s):  
Hamed Sattari Vayghan ◽  
Wojciech J Nawrocki ◽  
Christo Schiphorst ◽  
Dimitri Tolleter ◽  
Hu Chen ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Cross Section ◽  
Photosystem I ◽  
Absorption Cross Section ◽  
Light Harvesting ◽  
Higher Plants ◽  
Oxygenic Photosynthesis ◽  
Growth Delay ◽  
Absorption Cross ◽  
Light Harvesting Complexes

Light absorbed by chlorophylls of photosystem II and I drives oxygenic photosynthesis. Light-harvesting complexes increase the absorption cross-section of these photosystems. Furthermore, these complexes play a central role in photoprotection by dissipating the excess of absorbed light energy in an inducible and regulated fashion. In higher plants, the main light-harvesting complex is the trimeric LHCII. In this work, we used CRISPR/Cas9 to knockout the five genes encoding LHCB1, which is the major component of the trimeric LHCII. In absence of LHCB1 the accumulation of the other LHCII isoforms was only slightly increased, thereby resulting in chlorophyll loss leading to a pale green phenotype and growth delay. Photosystem II absorption cross-section was smaller while photosystem I absorption cross-section was unaffected. This altered the chlorophyll repartition between the two photosystems, favoring photosystem I excitation. The equilibrium of the photosynthetic electron transport was partially maintained by a lower photosystem I over photosystem II reaction center ratio and by the dephosphorylation of LHCII and photosystem II. Loss of LHCB1 altered the thylakoid structure, with less membrane layers per grana stack and reduced grana width. Stable LHCB1 knock out lines allow characterizing the role of this protein in light harvesting and acclimation and pave the way for future in vivo mutational analyses of LHCII.

scholarly journals The plastome-encoded PsaJ subunit is required for efficient Photosystem I excitation, but not for plastocyanin oxidation in tobacco

2007 ◽  
Vol 403 (2) ◽  
pp. 251-260 ◽  
Author(s):  
Mark A. Schöttler ◽  
Claudia Flügel ◽  
Wolfram Thiele ◽  
Sandra Stegemann ◽  
Ralph Bock
Keyword(s):  
Chlorophyll A ◽  
Photosystem I ◽  
Fluorescence Emission ◽  
Reaction Centre ◽  
Wild Type ◽  
Fluorescence Emission Spectra ◽  
Light Intensities ◽  
In The Wild ◽  
Assimilation Capacity

The functions of several small subunits of the large photosynthetic multiprotein complex PSI (Photosystem I) are not yet understood. To elucidate the function of the small plastome-encoded PsaJ subunit, we have produced knockout mutants by chloroplast transformation in tobacco (Nicotiana tabacum). PsaJ binds two chlorophyll-a molecules and is localized at the periphery of PSI, close to both the Lhca2- and Lhca3-docking sites and the plastocyanin-binding site. Tobacco psaJ-knockout lines do not display a visible phenotype. Despite a 25% reduction in the content of redox-active PSI, neither growth rate nor assimilation capacity are altered in the mutants. In vivo, redox equilibration of plastocyanin and PSI is as efficient as in the wild-type, indicating that PsaJ is not required for fast plastocyanin oxidation. However, PsaJ is involved in PSI excitation: altered 77 K chlorophyll-a fluorescence emission spectra and reduced accumulation of Lhca3 indicate that antenna binding and exciton transfer to the PSI reaction centre are impaired in ΔpsaJ mutants. Under limiting light intensities, growth of ΔpsaJ plants is retarded and the electron-transport chain is far more reduced than in the wild-type, indicating that PSI excitation might limit electron flux at sub-saturating light intensities. In addition to defining in vivo functions of PsaJ, our data may also have implications for the interpretation of the crystal structure of PSI.

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