Loss of a single chlorophyll in CP29 triggers re-organization of the Photosystem II supramolecular assembly

Guardini, Zeno; Gómez, Rodrigo; Caferri, Roberto; Dall’Osto, Luca; Bassi, Roberto

doi:10.1016/j.bbabio.2022.148555

Cited by 3 publications

(1 citation statement)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When plants are under a HL environment, avoiding photosynthetic yield decline is considered critical [91]. Photosystem II over-excitation increases the conversion of unquenched singlet excited state chlorophylls ( 1 Chl*) into triplet excited state chlorophylls ( 3 Chl*), accompanied by 1 O 2 generation that damages and inhibits PSII [29,39,40,64,[91][92][93]. The role of 1 O 2 is ambiguous; under moderate stress, it acts as a retrograde signal, whereas under severe stress, it causes oxidative damage [94].…”

Section: Discussionmentioning

confidence: 99%

Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants

Moustakas

Sperdouli

Adamakis

et al. 2022

IJMS

View full text Add to dashboard Cite

Salicylic acid (SA), an essential plant hormone, has received much attention due to its role in modulating the adverse effects of biotic and abiotic stresses, acting as an antioxidant and plant growth regulator. However, its role in photosynthesis under non stress conditions is controversial. By chlorophyll fluorescence imaging analysis, we evaluated the consequences of foliar applied 1 mM SA on photosystem II (PSII) efficiency of tomato (Solanum lycopersicum L.) plants and estimated the reactive oxygen species (ROS) generation. Tomato leaves sprayed with 1 mM SA displayed lower chlorophyll content, but the absorbed light energy was preferentially converted into photochemical energy rather than dissipated as thermal energy by non-photochemical quenching (NPQ), indicating photoprotective effects provided by the foliar applied SA. This decreased NPQ, after 72 h treatment by 1 mM SA, resulted in an increased electron transport rate (ETR). The molecular mechanism by which the absorbed light energy was more efficiently directed to photochemistry in the SA treated leaves was the increased fraction of the open PSII reaction centers (qp), and the increased efficiency of open reaction centers (Fv’/Fm’). SA induced a decrease in chlorophyll content, resulting in a decrease in non-regulated energy dissipated in PSII (ΦNO) under high light (HL) treatment, suggesting a lower amount of triplet excited state chlorophyll (3Chl*) molecules available to produce singlet oxygen (1O2). Yet, the increased efficiency, compared to the control, of the oxygen evolving complex (OEC) on the donor side of PSII, associated with lower formation of hydrogen peroxide (H2O2), also contributed to less creation of ROS. We conclude that under non stress conditions, foliar applied SA decreased chlorophyll content and suppressed phototoxicity, offering PSII photoprotection; thus, it can be regarded as a mechanism that reduces photoinhibition and photodamage, improving PSII efficiency in crop plants.

show abstract

Section: Discussionmentioning

confidence: 99%

Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants

Moustakas

Sperdouli

Adamakis

et al. 2022

IJMS

View full text Add to dashboard Cite

show abstract

Cryo-EM structure of a plant photosystem II supercomplex with light-harvesting protein Lhcb8 and α-tocopherol

Opatíková,

Semchonok,

Kopečný

et al. 2023

Nat. Plants

View full text Add to dashboard Cite

In vivoanalysis of the relationship between CP26 and qE-type NPQ via higher-orderArabidopsis cp26mutants

Walter,

Patel-Tupper,

Lam

et al. 2024

Preprint

View full text Add to dashboard Cite

CP26 is a monomeric minor light-harvesting complex of PSII (LHCII) protein that connects major LHCII trimers to the PSII core in photosynthetic thylakoid membranes. Previous studies have proposed that CP26 is not only involved in light harvesting but could also be involved in non-photochemical quenching (NPQ). Here, we analyzed higher-order Arabidopsis cp26 mutants using biophysical and pharmacological approaches to investigate the nature of NPQ and its relationship to known NPQ regulators (PSII subunit S (PsbS), the xanthophyll-converting enzyme VDE and the pH gradient across the thylakoid membrane). Maximum PSII quantum efficiencies (Fv/Fm) and chlorophyll fluorescence lifetimes in the dark were significantly lower in cp26 mutants, confirming that CP26 deficiency leads to a sustained quenched state even in the absence of light. Destabilized PSII-LHCII supercomplexes as observed with native PAGE analysis are the likely cause for this pre-quenched state, without other antenna proteins being able to rescue this phenotype. Further analyses revealed that cp26 mutants exhibit modest (single mutant) to highly significant (double mutants) reductions in overall NPQ capacity, which do not directly rely on PsbS and VDE (although the effect is more pronounced when these qE components are altered) but depend on thylakoid lumen acidification and protonation of protein residues. Together, these results show that the NPQ component lacking in cp26 mutants acts independently of qE and qZ and is induced in a slower phase of NPQ induction that most likely relies on pH-dependent conformational changes.

show abstract

Loss of a single chlorophyll in CP29 triggers re-organization of the Photosystem II supramolecular assembly

Cited by 3 publications

References 47 publications

Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants

Harnessing the Role of Foliar Applied Salicylic Acid in Decreasing Chlorophyll Content to Reassess Photosystem II Photoprotection in Crop Plants

Cryo-EM structure of a plant photosystem II supercomplex with light-harvesting protein Lhcb8 and α-tocopherol

In vivoanalysis of the relationship between CP26 and qE-type NPQ via higher-orderArabidopsis cp26mutants

Contact Info

Product

Resources

About