Non-photochemical Quenching Plays a Key Role in Light Acclimation of Rice Plants Differing in Leaf Color

Abstract Although N levels affect leaf photosynthetic capacity, the effects of N levels on the photochemistry of photosystems II and I (PSII and PSI, respectively) are not well-understood. In the present study, we examined this aspect in rice (Oryza sativa L. ‘Hitomebore’) plants grown under three different N levels at normal or high temperature that can occur during rice culture and does not severely suppress photosynthesis. At both growth temperatures, the quantum efficiency of PSII [Y(II)] and the fraction of the primary quinone electron acceptor in its oxidized state were positively correlated with the amount of total leaf-N, whereas the quantum yields of non-photochemical quenching and donor-side limitation of PSI [Y(ND)] were negatively correlated with the amount of total leaf-N. These changes in PSII and PSI parameters were strongly correlated with each other. Growth temperatures scarcely affected these relationships. These results suggest that the photochemistry of PSII and PSI is coordinately regulated primarily depending on the amount of total leaf-N. When excess light energy occurs in low-N acclimated plants, oxidation of the reaction center chlorophyll of PSI is thought to be stimulated to protect PSI from excess light energy. It is also suggested that PSII and PSI normally operate at high temperature used in the present study. In addition, as the relationships between Y(II) and Y(ND) were found to be almost identical to those observed in osmotically stressed rice plants, common regulation is thought to be operative when excess light energy occurs due to different causes.

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Light Absorption and Partitioning in Response to Nitrogen in Apple Leaves

HortScience ◽

10.21273/hortsci.33.3.541a ◽

1998 ◽

Vol 33 (3) ◽

pp. 541a-541

Author(s):

Lailiang Cheng ◽

Leslie H. Fuchigami ◽

Patrick J. Breen

Keyword(s):

High Light ◽

Thermal Dissipation ◽

Photochemical Quenching ◽

Light Conditions ◽

Psii Efficiency ◽

Fluorescence Measurements ◽

Free Radical Formation ◽

Highly Correlated ◽

Non Photochemical Quenching ◽

Leaf N

Bench-grafted Fuji/M26 apple trees were fertigated with different concentrations of nitrogen by using a modified Hoagland solution for 6 weeks, resulting in a range of leaf N from 1.0 to 4.3 g·m–2. Over this range, leaf absorptance increased curvilinearly from 75% to 92.5%. Under high light conditions (1500 (mol·m–2·s–1), the amount of absorbed light in excess of that required to saturate CO2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range except for a slight drop at the lower end. As leaf N increased, non-photochemical quenching under high light declined and there was a corresponding increase in the efficiency with which the absorbed photons were delivered to open PSII centers. Photochemical quenching coefficient decreased significantly at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO2 assimilation. The fraction of absorbed light potentially used for free radical formation was estimated to be about 10% regardless of the leaf N status. It was concluded that increased thermal dissipation protected leaves from photo-oxidation as leaf N declined.

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Gradual Response of Cyanobacterial Thylakoids to Acute High-Light Stress—Importance of Carotenoid Accumulation

Cells ◽

10.3390/cells10081916 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1916

Author(s):

Myriam Canonico ◽

Grzegorz Konert ◽

Aurélie Crepin ◽

Barbora Šedivá ◽

Radek Kaňa

Keyword(s):

Single Cell ◽

Thylakoid Membrane ◽

Intermediate Phase ◽

Light Stress ◽

Fast Response ◽

High Light ◽

Photochemical Quenching ◽

Second Phase ◽

Ros Scavenging ◽

Non Photochemical Quenching

Light plays an essential role in photosynthesis; however, its excess can cause damage to cellular components. Photosynthetic organisms thus developed a set of photoprotective mechanisms (e.g., non-photochemical quenching, photoinhibition) that can be studied by a classic biochemical and biophysical methods in cell suspension. Here, we combined these bulk methods with single-cell identification of microdomains in thylakoid membrane during high-light (HL) stress. We used Synechocystis sp. PCC 6803 cells with YFP tagged photosystem I. The single-cell data pointed to a three-phase response of cells to acute HL stress. We defined: (1) fast response phase (0–30 min), (2) intermediate phase (30–120 min), and (3) slow acclimation phase (120–360 min). During the first phase, cyanobacterial cells activated photoprotective mechanisms such as photoinhibition and non-photochemical quenching. Later on (during the second phase), we temporarily observed functional decoupling of phycobilisomes and sustained monomerization of photosystem II dimer. Simultaneously, cells also initiated accumulation of carotenoids, especially ɣ–carotene, the main precursor of all carotenoids. In the last phase, in addition to ɣ-carotene, we also observed accumulation of myxoxanthophyll and more even spatial distribution of photosystems and phycobilisomes between microdomains. We suggest that the overall carotenoid increase during HL stress could be involved either in the direct photoprotection (e.g., in ROS scavenging) and/or could play an additional role in maintaining optimal distribution of photosystems in thylakoid membrane to attain efficient photoprotection.

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The Role of Acidic Residues in the C Terminal Tail of the LHCSR3 Protein of Chlamydomonas reinhardtii in Non-Photochemical Quenching

The Journal of Physical Chemistry Letters ◽

10.1021/acs.jpclett.1c01382 ◽

2021 ◽

pp. 6895-6900

Author(s):

Franco V. A. Camargo ◽

Federico Perozeni ◽

Gabriel de la Cruz Valbuena ◽

Luca Zuliani ◽

Samim Sardar ◽

...

Keyword(s):

Chlamydomonas Reinhardtii ◽

Photochemical Quenching ◽

Acidic Residues ◽

Non Photochemical Quenching

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Effects of iron limitation on carbon balance and photophysiology of the Antarctic diatom Chaetoceros cf. simplex

Polar Biology ◽

10.1007/s00300-020-02785-1 ◽

2021 ◽

Author(s):

Deborah Bozzato ◽

Torsten Jakob ◽

Christian Wilhelm ◽

Scarlett Trimborn

Keyword(s):

Oxygen Evolution ◽

Photochemical Quenching ◽

Gross Photosynthesis ◽

Manganese Zinc ◽

C Cycle ◽

Uptake Rates ◽

Carbon Pump ◽

Non Photochemical Quenching ◽

The Antarctic ◽

Biological Carbon Pump

AbstractIn the Southern Ocean (SO), iron (Fe) limitation strongly inhibits phytoplankton growth and generally decreases their primary productivity. Diatoms are a key component in the carbon (C) cycle, by taking up large amounts of anthropogenic CO2 through the biological carbon pump. In this study, we investigated the effects of Fe availability (no Fe and 4 nM FeCl3 addition) on the physiology of Chaetoceros cf. simplex, an ecologically relevant SO diatom. Our results are the first combining oxygen evolution and uptake rates with particulate organic carbon (POC) build up, pigments, photophysiological parameters and intracellular trace metal (TM) quotas in an Fe-deficient Antarctic diatom. Decreases in both oxygen evolution (through photosynthesis, P) and uptake (respiration, R) coincided with a lowered growth rate of Fe-deficient cells. In addition, cells displayed reduced electron transport rates (ETR) and chlorophyll a (Chla) content, resulting in reduced cellular POC formation. Interestingly, no differences were observed in non-photochemical quenching (NPQ) or in the ratio of gross photosynthesis to respiration (GP:R). Furthermore, TM quotas were measured, which represent an important and rarely quantified parameter in previous studies. Cellular quotas of manganese, zinc, cobalt and copper remained unchanged while Fe quotas of Fe-deficient cells were reduced by 60% compared with High Fe cells. Based on our data, Fe-deficient Chaetoceros cf. simplex cells were able to efficiently acclimate to low Fe conditions, reducing their intracellular Fe concentrations, the number of functional reaction centers of photosystem II (RCII) and photosynthetic rates, thus avoiding light absorption rather than dissipating the energy through NPQ. Our results demonstrate how Chaetoceros cf. simplex can adapt their physiology to lowered assimilatory metabolism by decreasing respiratory losses.

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