scholarly journals Plant Photochemistry, Reactive Oxygen Species, and Photoprotection

Photochem ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 5-8
Author(s):  
Michael Moustakas
Keyword(s):  
Reactive Oxygen Species ◽  
Photosystem Ii ◽  
Photosystem I ◽  
Charge Separation ◽  
Light Harvesting ◽  
Oxygen Species ◽  
Light Harvesting Complexes ◽  
Cytochrome B6f ◽  
Reaction Centres ◽  
Electron Carriers

Light energy, absorbed as photons by chlorophylls and other pigment molecules consisting of light-harvesting complexes (LHCs), is transferred to the reaction centres (RCs), where, through charge separation, electrons flow from photosystem II (PSII) through cytochrome b6f and diffusible electron carriers to photosystem I (PSI) [...]

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 natural design for harvesting far-red light: the antenna increases both absorption and quantum efficiency of Photosystem II

2021 ◽  
Author(s):  
Vincenzo Mascoli ◽  
Ahmad Farhan Bhatti ◽  
Luca Bersanini ◽  
Herbert van Amerongen ◽  
Roberta Croce
Keyword(s):  
Photosystem Ii ◽  
Charge Separation ◽  
Light Harvesting ◽  
Structural Information ◽  
Red Light ◽  
Time Resolved Fluorescence ◽  
Light Harvesting Complexes ◽  
Time Resolved ◽  
Light Energy Conversion ◽  
Chlorophyll F

Cyanobacteria carry out photosynthetic light-energy conversion using phycobiliproteins for light harvesting and the chlorophyll-rich photosystems for photochemistry. While most cyanobacteria only absorb visible photons, some of them can acclimate to harvest far-red light (FRL, 700-800 nm) by integrating chlorophyll f and d in their photosystems and producing red-shifted allophycocyanin. Chlorophyll f insertion enables the photosystems to use FRL but slows down charge separation, reducing photosynthetic efficiency. Here we demonstrate with time-resolved fluorescence spectroscopy that charge separation in chlorophyll-f-containing Photosystem II becomes faster in the presence of red-shifted allophycocyanin antennas. This is different from all known photosynthetic systems, where additional light-harvesting complexes slow down charge separation. Based on the available structural information, we propose a model for the connectivity between the phycobiliproteins and Photosystem II that qualitatively accounts for our spectroscopic data. This unique design is probably important for these cyanobacteria to efficiently switch between visible and far-red light.

Structural Role of Carotenoids in Photosynthetic Membranes

1996 ◽  
Vol 51 (11-12) ◽  
pp. 763-771 ◽  
Author(s):  
Andrey A Moskalenko ◽  
Navassard V Karapetyan
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Purple Bacteria ◽  
Reaction Centers ◽  
Structural Components ◽  
Light Harvesting Complexes ◽  
Photosynthetic Membranes

Besides the light-harvesting and protecting role, carotenoids are also instrumental as structural components for the assembly of light-harvesting complexes in purple bacteria and green plants, as well as for the formation of photosystem II complex. Carotenoids stabilize those pigm ent-protein complexes, but have no effect on the form ation of the reaction centers of purple bacteria and photosystem I of plants.

Variable stoichiometries of photosystem II to photosystem I reaction centres

1988 ◽  
Vol 17 (3) ◽  
pp. 277-281 ◽  
Author(s):  
W. S. Chow ◽  
Jan M. Anderson ◽  
A. B. Hope
Keyword(s):  
Photosystem Ii ◽  
Photosystem I ◽  
Reaction Centres
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