Effects of NaCl salinity on some leaf nutrient concentrations, non-photochemical quenching and the efficiency of the PSII photochemistry of two Iranian pomegranate varieties under greenhouse and field conditions: Preliminary results

Two xanthophyll cycles are present in higher plants: the ubiquitous violaxanthin (V) cycle and the taxonomically restricted lutein epoxide (Lx) cycle. Conversions of V to zeaxanthin (Z) in the first and Lx to lutein (L) in the second happen in parallel under illumination. Unlike the V cycle, in which full epoxidation is completed overnight, in the Lx cycle, this reaction has been described as irreversible on a daily basis in most species (the ‘truncated’ Lx cycle). However, there are some species that display complete restoration of Lx overnight (‘true’ Lx cycle). So far, little is known about the physiological meaning of these two versions of the Lx cycle. Therefore, in the present work, the ‘true’ Lx cycle operation was studied in seedlings of Ocotea foetens (Aiton) Benth. under controlled and field conditions. Complete overnight recovery of the Lx pool in the presence of norfluorazon suggested that the inter-conversions between Lx and L represent a true cycle in this species. Furthermore, Lx responded dynamically to environmental conditions during long-term acclimation. Our data demonstrate the operation of a ‘true’ Lx cycle and, for the first time, its potential involvement in the regulation of non-photochemical quenching in situ. We propose dual regulation of Lx cycle in O. foetens, in which the extent of Lx restoration depends on the intensity and duration of illumination.

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Changes in Photo-Protective Energy Dissipation of Photosystem II in Response to Beneficial Bacteria Consortium in Durum Wheat under Drought and Salinity Stresses

Applied Sciences ◽

10.3390/app10155031 ◽

2020 ◽

Vol 10 (15) ◽

pp. 5031 ◽

Cited By ~ 1

Author(s):

Mohammad Yaghoubi Khanghahi ◽

Sabrina Strafella ◽

Carmine Crecchio

Keyword(s):

Chlorophyll Fluorescence ◽

Energy Dissipation ◽

Quantum Yield ◽

Photosystem Ii ◽

Excitation Energy ◽

Durum Wheat ◽

Photochemical Quenching ◽

Plant Growth Promoting Bacteria ◽

Psii Photochemistry ◽

Non Photochemical Quenching

The present research aimed at evaluating the harmless dissipation of excess excitation energy by durum wheat (Triticum durum Desf.) leaves in response to the application of a bacterial consortium consisting of four plant growth-promoting bacteria (PGPB). Three pot experiments were carried out under non-stress, drought (at 40% field capacity), and salinity (150 mM NaCl) conditions. The results showed that drought and salinity affected photo-protective energy dissipation of photosystem II (PSII) increasing the rate of non-photochemical chlorophyll fluorescence quenching (NPQ (non-photochemical quenching) and qCN (complete non-photochemical quenching)), as well as decreasing the total quenching of chlorophyll fluorescence (qTQ), total quenching of variable chlorophyll fluorescence (qTV) and the ratio of the quantum yield of actual PSII photochemistry, in light-adapted state to the quantum yield of the constitutive non-regulatory NPQ (PQ rate). Our results also indicated that the PGPB inoculants can mitigate the adverse impacts of stresses on leaves, especially the saline one, in comparison with the non-fertilized (control) treatment, by increasing the fraction of light absorbed by the PSII antenna, PQ ratio, qTQ, and qTV. In the light of findings, our beneficial bacterial strains showed the potential in reducing reliance on traditional chemical fertilizers, in particular in saline soil, by improving the grain yield and regulating the amount of excitation energy.

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Hormetic Responses of Photosystem II in Tomato to Botrytis cinerea

Plants ◽

10.3390/plants10030521 ◽

2021 ◽

Vol 10 (3) ◽

pp. 521

Author(s):

Maria-Lavrentia Stamelou ◽

Ilektra Sperdouli ◽

Ioanna Pyrri ◽

Ioannis-Dimosthenis S. Adamakis ◽

Michael Moustakas

Keyword(s):

Photosystem Ii ◽

Botrytis Cinerea ◽

Defense Response ◽

Gray Mold ◽

Spore Suspension ◽

Photochemical Quenching ◽

Adjacent Area ◽

Solanum Lycopersicum L ◽

Psii Photochemistry ◽

Non Photochemical Quenching

Botrytis cinerea, a fungal pathogen that causes gray mold, is damaging more than 200 plant species, and especially tomato. Photosystem II (PSII) responses in tomato (Solanum lycopersicum L.) leaves to Botrytis cinerea spore suspension application were evaluated by chlorophyll fluorescence imaging analysis. Hydrogen peroxide (H2O2) that was detected 30 min after Botrytis application with an increasing trend up to 240 min, is possibly convening tolerance against B. cinerea at short-time exposure, but when increasing at relative longer exposure, is becoming a damaging molecule. In accordance, an enhanced photosystem II (PSII) functionality was observed 30 min after application of B. cinerea, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in a significant decrease in the dissipated non-regulated energy (ΦNO), indicating a possible decreased singlet oxygen (1O2) formation, thus specifying a modified reactive oxygen species (ROS) homeostasis. Therefore, 30 min after application of Botrytis spore suspension, before any visual symptoms appeared, defense response mechanisms were triggered, with PSII photochemistry to be adjusted by NPQ in a such way that PSII functionality to be enhanced, but being fully inhibited at the application spot and the adjacent area, after longer exposure (240 min). Hence, the response of tomato PSII to B. cinerea, indicates a hormetic temporal response in terms of “stress defense response” and “toxicity”, expanding the features of hormesis to biotic factors also. The enhanced PSII functionality 30 min after Botrytis application can possible be related with the need of an increased sugar production that is associated with a stronger plant defense potential through the induction of defense genes.

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Photosynthesis, light energy partitioning, and photoprotection in the shade-demanding species Panax notoginseng under high and low level of growth irradiance

Functional Plant Biology ◽

10.1071/fp15283 ◽

2016 ◽

Vol 43 (6) ◽

pp. 479 ◽

Cited By ~ 11

Author(s):

Jun-Wen Chen ◽

Shuang-Bian Kuang ◽

Guang-Qiang Long ◽

Sheng-Chao Yang ◽

Zhen-Gui Meng ◽

...

Keyword(s):

Panax Notoginseng ◽

High Light ◽

Light Energy ◽

Quantum Yields ◽

Photochemical Quenching ◽

Light Illumination ◽

Low Light ◽

Psii Photochemistry ◽

Growth Irradiance ◽

Non Photochemical Quenching

Partitioning of light energy into several pathways and its relation to photosynthesis were examined in a shade-demanding species Panax notoginseng (Burkill) F.H.Chen ex C.Y.Wu & K.M.Feng grown along a light gradient. In fully light-induced leaves, the actual efficiency of PSII photochemistry (ΔF/Fmʹ), electron transport rate (ETR), non-photochemical quenching (NPQ) and photochemical quenching (qP) were lower in low-light-grown plants; this was also the case in fully dark-adapted leaves under a simulated sunfleck. In response to varied light intensity, high-light-grown plants showed greater quantum yields of light-dependent non-photochemical quenching (ΦNPQ) and PSII photochemistry (ΦPSII) and smaller quantum yields of fluorescence and constitutive thermal dissipation (Φf,d). Under the simulated sunfleck, high-light-grown plants showed greater ΦPSII and smaller Φf,d. There were positive relationships between net photosynthesis (Anet) and ΦNPQ+f,d and negative relationships between Anet and ΦPSII in fully light-induced leaves; negative correlations of Anet with ΦNPQ+f,d and positive correlations of Anet with ΦPSII were observed in fully dark-adapted leaves. In addition, more nitrogen was partitioned to light-harvesting components in low-light-grown plants, whereas leaf morphology and anatomy facilitate reducing light capture in high-light-grown plants. The pool of xanthophyll pigments and the de-epoxidation state was greater in high-light-grown plants. Antioxidant defence was elevated by increased growth irradiance. Overall, the evidences from P. notoginseng suggest that in high-light-grown shade-demanding plants irradiated by high light more electrons were consumed by non-net carboxylative processes that activate the component of NPQ, that low-light-grown plants correspondingly protect the photosynthetic apparatus against photodamage by reducing the efficiency of PSII photochemistry under high light illumination, and that during the photosynthetic induction, the ΔpH-dependent (qE) component of NPQ might dominate photoprotection, but the NPQ also depresses the enhancement of photosynthesis via competition for light energy.

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Short-term temperature dependency of the photosynthetic and PSII photochemical responses to photon flux density of leaves of Vitis vinifera cv. Shiraz vines grown in field conditions with and without fruit

Functional Plant Biology ◽

10.1071/fp18324 ◽

2019 ◽

Vol 46 (7) ◽

pp. 634 ◽

Cited By ~ 1

Author(s):

Dennis H. Greer

Keyword(s):

Maximum Efficiency ◽

Photon Flux ◽

Photochemical Quenching ◽

Photon Flux Density ◽

Temperature Dependent ◽

Psii Photochemistry ◽

Acclimation Response ◽

Summer Temperatures ◽

Non Photochemical Quenching ◽

The Impact

Shiraz vines grown outdoors with and without a crop load were used to determine photosynthetic and chlorophyll fluorescence responses to light across a range of leaf temperatures to evaluate the impact of presence/absence of a sink on these responses. Results indicate maximum rates of photosynthesis and light saturation in fruiting vines were biased towards higher temperatures whereas these processes in vegetative vines were biased towards lower temperatures. The maximum efficiency of PSII photochemistry was similarly biased, with higher efficiency for the vegetative vines below 30°C and a higher efficiency for the fruiting vines above. The quantum efficiency of PSII electron transport was generally higher across all temperatures in the fruiting compared with vegetative vines. Photochemical quenching was not sensitive to temperature in fruiting vines but strongly so in vegetative vines, with an optimum at 30°C and marked increases in photochemical quenching at other temperatures. Non-photochemical quenching was not strongly temperature dependent, but there were marked increases in both treatments at 45°C, consistent with marked decreases in assimilation. These results suggest demand for assimilates in fruiting vines induced an acclimation response to high summer temperatures to enhance assimilate supply and this was underpinned by comparable shifts in PSII photochemistry.

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Cotton leaf nutrient concentrations in response to waterlogging under field conditions

Field Crops Research ◽

10.1016/j.fcr.2009.05.012 ◽

2009 ◽

Vol 113 (3) ◽

pp. 246-255 ◽

Cited By ~ 44

Author(s):

Stephen P. Milroy ◽

Michael P. Bange ◽

Pongmanee Thongbai

Keyword(s):

Field Conditions ◽

Nutrient Concentrations ◽

Cotton Leaf ◽

Leaf Nutrient Concentrations

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A Chlorophyll-Less Barley Mutant “NYB” Is Insensitive to Water Stress

Zeitschrift für Naturforschung C ◽

10.1515/znc-2007-5-614 ◽

2007 ◽

Vol 62 (5-6) ◽

pp. 403-409 ◽

Cited By ~ 10

Author(s):

Shu Yuan ◽

Wen-Juan Liu ◽

Tao Lei ◽

Ming-Hua Luo ◽

Jun-Bo Du ◽

...

Keyword(s):

Water Stress ◽

Maximum Efficiency ◽

Photochemical Quenching ◽

Wild Type ◽

Energy Capture ◽

Barley Mutant ◽

Core Proteins ◽

Psii Photochemistry ◽

Non Photochemical Quenching ◽

Quantum Yield Of Psii

“NYB” is a chlorophyll-less barley mutant, which grows relatively slow and unhealthily. The effects of water stress on photosystem II (PSII) of NYB and its wild type (WT) were investigated. Unexpected results indicated that the mutant was more resistant to water stress, because: PSII core proteins D1, D2 and LHCII declined more in WT than in NYB under water stress, and the corresponding psbA, psbD and cab mRNAs also decreased more dramatically in WT; CO2 assimilation, stomatal conductance, maximum efficiency of PSII photochemistry (Fv/Fm), efficiency of excitation energy capture by open PSII reaction centres (Fv’/Fm’), quantum yield of PSII electron transport (φPSII) and DCIP photoreduction in NYB were less sensitive to water stress than in WT, although the non-photochemical quenching coefficient (qN) and the photochemical quenching coefficient (qP) were almost the same in NYB and WT. Effective chlorophyll utilization and improved PSII protein formation in the mutant may be the reason for the enhanced stress resistance. Other possible mechanisms are also discussed.

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Phosphate Deficiency Increases the Rate Constant of Thermal Dissipation of Excitation Energy by Photosystem II in Intact Leaves of Sunflower and Maize.

Functional Plant Biology ◽

10.1071/pp9950417 ◽

1995 ◽

Vol 22 (3) ◽

pp. 417 ◽

Cited By ~ 11

Author(s):

J Jacob

Keyword(s):

Excitation Energy ◽

Rate Constant ◽

Thermal Dissipation ◽

Phosphate Deficiency ◽

Photon Flux ◽

Photochemical Quenching ◽

Variable Fluorescence ◽

Psii Photochemistry ◽

Non Photochemical Quenching

Sunflower (Helianthus annuus L.) and maize (Zea mays L.) plants were grown in controlled environment chambers either with adequate supply or no external supply of inorganic phosphate. On the third fully-expanded leaves, chlorophyll fluorescence from photosystem II (PSII) was measured using a modulated fluorescence measuring system at various photon flux densities at room temperature. Phosphate deficiency resulted in an increase in the coefficient of non-photochemical quenching and a decrease in the coefficient of photochemical quenching of variable fluorescence. The efficiency of excitation energy capture by open PSII reaction centres and quantum yield of PSII photochemistry were decreased with phosphate deficiency. There was a significant effect of phosphate deficiency on in vivo PSII photochemistry which was independent of changes in thylakoid membrane energisation induced by the actinic light. An increase in the non-photochemical quenching of variable fluorescence with phosphate deficiency was due to an increased rate constant of thermal dissipation of excitation energy by PSII. Analyses of fluorescence signals suggest that phosphate deficiency decreased the rate constant of PSII photochemistry as well as the probability of excitation energy transfer from PSII antenna to PSII reaction centre. These effects were more apparent at low photon flux densities than at high photon flux densities. Regulation of energy transduction in the thylakoid and in vivo PSII activity in response to the physical environment of the plant are important aspects of environmental regulation of photosynthesis.

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Photon flux density and temperature-dependent responses of photosynthesis and photosystem II performance of apple leaves grown in field conditions

Functional Plant Biology ◽

10.1071/fp15068 ◽

2015 ◽

Vol 42 (8) ◽

pp. 782 ◽

Cited By ~ 7

Author(s):

Dennis H. Greer

Keyword(s):

Electron Transport ◽

Flux Density ◽

Leaf Temperature ◽

Field Conditions ◽

Photon Flux ◽

Photochemical Quenching ◽

Photon Flux Density ◽

Temperature Dependent ◽

Light Responses ◽

Non Photochemical Quenching

The process of photosynthesis depends on the light, and is modulated by leaf temperature and their interaction is important to understand how climate affects photosynthesis. Photosynthetic and PSII light responses at a range of leaf temperatures were measured on leaves of apple (Malus domestica Borkh. cv. Red Gala) trees growing in field conditions. The objective was to assess the interaction between photon flux density (PFD) and temperature on these processes. Results showed leaf temperature strongly modulated the PFD-dependent response of photosynthesis and PSII performance. An interaction on photosynthesis occurred, with temperature affecting saturated rates as well as PFDs saturating photosynthesis. The efficiency of PSII electron transport (operating and maximum in light) universally declined with increasing PFD but temperature strongly influenced the response. Rates of PSII electron transport at saturating PFDs were affected by temperatures. Both photochemical quenching and non-photochemical quenching also responded strongly to temperature but at high PFDs, photochemical quenching increased linearly with decreasing temperatures while non-photochemical quenching increased curvilinearly with increasing temperatures. Modelling revealed changes in photosynthesis were positively correlated with rates of electron transport. These results greatly enhance our understanding of photosynthesis and the underpinning processes and their responses to temperature and PFD.

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Rapid Hormetic Responses of Photosystem II Photochemistry to Cadmium Exposure

10.20944/preprints202011.0283.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ioannis-Dimosthenis S. Adamakis ◽

Ilektra Sperdouli ◽

Anetta Hanć ◽

Anelia Dobrikova ◽

Emilia Apostolova ◽

...

Keyword(s):

Photosystem Ii ◽

Chloroplast Ultrastructure ◽

Photochemical Quenching ◽

Psii Efficiency ◽

Salvia Sclarea ◽

Whole Plant ◽

Short Period ◽

Psii Photochemistry ◽

Non Photochemical Quenching ◽

Short Time

Five-day exposure of clary sage (Salvia sclarea) to 100 μM cadmium (Cd) in hydroponics was sufficient to increase Cd concentrations significantly in roots and aboveground parts and affect negatively whole plant levels of calcium (Ca) and magnesium (Mg), since Cd competes for Ca channels, while reduced Mg concentrations are associated with increased Cd tolerance. Total zinc (Zn), copper (Cu), and iron (Fe) uptake increased but their translocation to the aboveground parts decreased possible due to translocation barriers. Despite the substantial levels of Cd in leaves, without any observed defects on chloroplast ultrastructure, an enhanced photosystem II (PSII) efficiency was observed, with a higher fraction of absorbed light energy to be directed to photochemistry (ΦPSΙΙ). The concomitant increase in the photoprotective mechanism of non-photochemical quenching of photosynthesis (NPQ) resulted in an important decrease in the dissipated non-regulated energy (ΦNO), modifying the homeostasis of reactive oxygen species (ROS), through a decreased singlet oxygen (1O2) formation. Thus, when clary sage was exposed to Cd for a short period, tolerance mechanisms were triggered, with PSII photochemistry to be regulated by NPQ in such a way that PSII efficiency to be enhanced. However, exposure to a combination of Cd and high light or for longer duration (8 days) to Cd alone, resulted in an inhibition of PSII functionality pointing out towards Cd toxicity. Thus, the rapid activation of PSII functionality at short time exposures and the inhibition at longer duration suggests a hormetic response and describes these effects in terms of “adaptive response” and “toxicity”, respectively.

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