Xanthophyll cycle, light energy dissipation and photosystem II down-regulation in senescent leaves of wheat plants grown in the field

2001 ◽  
Vol 28 (10) ◽  
pp. 1023 ◽  
Author(s):  
Congming Lu ◽  
Qingtao Lu ◽  
Jianhua Zhang ◽  
Qide Zhang ◽  
Tingyun Kuang
Keyword(s):  
Energy Dissipation ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Xanthophyll Cycle ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Down Regulation ◽  
Psii Efficiency ◽  
Psii Photochemistry ◽  
Assimilation Capacity

Photosynthesis, the xanthophyll cycle, light energy dissipation and down-regulation of photosystem II (PSII) in senescent leaves of wheat plants grown in the field were investigated. With the progress of senescence, maximal efficiency of PSII photochemistry decreased only slightly early in the morning but substantially at midday. Actual PSII efficiency, photochemical quenching, efficiency of excitation capture by open PSII centres, and the I–P phase of fluorescence induction curves decreased significantly and such decreases were much more evident at midday than in the morning. At the same time, non-photochemical quenching, thermal dissipation and de-epoxidation status of the xanthophyll cycle increased, with much greater increases at midday than in the morning. These results suggest that the xanthophyll cycle played a role in photoprotection of PSII in senescent leaves by dissipating excess excitation energy. Taking into account the substantial decrease in photosynthetic capacity in senescent leaves, our data seem to support the view that the decrease in actual PSII efficiency in senescent leaves may represent a mechanism to down-regulate photosynthetic electron transport to match the decreased CO2 assimilation capacity and avoid photodamage of PSII from excess excitation energy.

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

2020 ◽  
Vol 10 (15) ◽  
pp. 5031 ◽  
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.

Photochemistry and xanthophyll cycle-dependent energy dissipation in differently oriented cladodes of Opuntia stricta during the winter

1998 ◽  
Vol 25 (1) ◽  
pp. 95 ◽  
Author(s):  
David H. Barker ◽  
Barry A. Logan ◽  
William W. Adams III ◽  
Barbara Demmig-Adams
Keyword(s):  
Energy Dissipation ◽  
Excitation Energy ◽  
Xanthophyll Cycle ◽  
Photosynthetic Apparatus ◽  
High Rate ◽  
Psii Efficiency ◽  
Thermal Energy Dissipation ◽  
Dramatic Decline ◽  
Absorption Of Light ◽  
Cycle Dependent

The photosynthetic and energy dissipation responses of four differently oriented photosynthetic surfaces (cladodes) from the cactus Opuntia stricta (Haw.) Haw. were studied in the field during the winter in Australia. Even under very low PFD (i.e. -2 s-1) all surfaces experienced a dramatic decline in photosystem II (PSII) efficiency during the morning period when temperatures were below freezing. However, light energy absorbed during the warmer afternoon period was more efficiently utilised for photochemistry with less diversion through the thermal energy dissipation pathway. Low temperature presumably reduced the proportion of excitation energy that could be utilised photosynthetically, resulting in a high rate of energy dissipation with a concomitant decline in PSII efficiency. A lag in the diurnal de-acidification of malic acid, and therefore the availability of endogenous CO2, may have also contributed to the low rate of photochemistry during the morning period. We interpret the increase in energy dissipation and decline in PSII efficiency as a controlled response of PSII that is dependent upon the de-epoxidised components of the xanthophyll cycle under conditions when the absorption of light exceeds the capacity of the photosynthetic apparatus to process the excitation energy through photochemistry.

Xanthophyll Cycle-Dependent Energy Dissipation and Flexible Photosystem II Efficiency in Plants Acclimated to Light Stress

1995 ◽  
Vol 22 (2) ◽  
pp. 249 ◽  
Author(s):  
B Demmig-Adams ◽  
WW Iii Adams ◽  
BA Logan ◽  
AS Verhoeven
Keyword(s):  
Energy Dissipation ◽  
Photosystem Ii ◽  
Xanthophyll Cycle ◽  
Light Stress ◽  
Photon Flux ◽  
Growth Environment ◽  
Psii Efficiency ◽  
Cycle Dependent ◽  
Shade Leaves ◽  
Sun Leaves

The effect of an acclimation to light stress during the growth of leaves on their response to high photon flux densities (PFDs) was characterised by quantifying changes in photosystem II (PSII) characteristics and carotenoid composition. During brief experimental exposures to high PFDs sun leaves exhibited: (a) much higher levels of antheraxanthin + zeaxanthin than shade leaves, (b) a greater extent of energy dissipation in the light-harvesting antennae, and (c) a greater decrease of intrinsic PSII efficiency that was rapidly reversible. During longer experimental exposures to high PFD, deep-shade leaves but not the sun leaves showed slowly developing secondary decreases in intrinsic PSII efficiency. Recovery of these secondary responses was also slow and inhibited by lincomycin, an inhibitor of chloroplast-encoded protein synthesis. In contrast, under field conditions all changes in intrinsic PSII efficiency in open sun-exposed habitats as well as understory sites with intense sunflecks appeared to be caused by xanthophyll cycle-dependent energy dissipation. Furthermore, comparison of leaves with different maximal rates of electron transport revealed that all leaves compensated fully for these differences by dissipating very different amounts of absorbed light via xanthophyll cycle-dependent energy dissipation, thereby all maintaining a similarly low PSII reduction state. It is our conclusion that an increased capacity for xanthophyll cycle-dependent energy dissipation is a key component of the acclimation of leaves to a variety of different forms of light stress, and that the response of leaves to excess light experienced in the growth environment is thus likely to be qualitatively different from that to sudden experimental exposures to PFDs exceeding the growth PFD.

scholarly journals Rapid Hormetic Responses of Photosystem II Photochemistry to Cadmium Exposure

2020 ◽  
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.

Carotenoids and Photosystem II Characteristics of Upper and Lower Halves of Leaves Acclimated to High Light

1996 ◽  
Vol 23 (6) ◽  
pp. 669 ◽  
Author(s):  
WW Iii Adams ◽  
B Demmig-Adams ◽  
DH Barker ◽  
S Kiley
Keyword(s):  
Chlorophyll Fluorescence ◽  
Photosystem Ii ◽  
Excitation Energy ◽  
Total Energy ◽  
Xanthophyll Cycle ◽  
Lower Surface ◽  
Thylakoid Membranes ◽  
High Light ◽  
Pigment Composition ◽  
Light Gradient

Acclimation of the leaves or stems of four succulent species to different light environments and to the light gradient across high light-acclimated tissues was examined through measurements of chlorophyll fluorescence and characterisation of the pigment composition of the thylakoid membranes. Whereas the total amounts of light striking the upper (sun-exposed) and lower (self-shaded) surfaces were quite different, resulting in a much smaller pool of the xanthophyll cycle carotenoids in the lower halves of high light-acclimated tissues, the conversion state of the xanthophyll cycle (the degree to which violaxanthin is converted to antheraxanthin and zeaxanthin) was similar throughout the tissues during exposure to natural sunlight. Under full sunlight, less than 25% of the light absorbed by the upper surface was utilised through photosynthesis, with the majority of the remaining excitation energy being dissipated thermally. In contrast, a considerably greater fraction of the light absorbed by the lower surface was utilised in photosynthesis, ranging from one-third to more than two-thirds of the total energy absorbed.

Light energy dissipation in Quercus ilex resprouts after fire

2000 ◽  
Vol 27 (2) ◽  
pp. 129 ◽  
Author(s):  
Isabel Fleck ◽  
Xavier Aranda ◽  
Bouchra El Omari ◽  
Jon Permanyer ◽  
Anunciación Abadía ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Quercus Ilex ◽  
Photosynthetic Capacity ◽  
Leaf Age ◽  
Photochemical Efficiency ◽  
Photosynthetic Apparatus ◽  
High Irradiance ◽  
Light Energy ◽  
Photochemical Quenching ◽  
Sink Strength

Holm oak (Quercus ilex) plants that have resprouted after fire have higher photosynthetic capacity than control plants in intact vegetation. In this study, branches detached from forest plants were fed with dithiothreitol (DTT) in the laboratory to inhibit zeaxanthin production and thus reduce the dissipation of light energy as heat. This allowed us to test the hypothesis that plants with greater photosynthetic capacity, and therefore greater photo-chemical sink strength, would suffer a lower reduction in photochemical efficiency under stressful conditions. Greater rates of photochemistry in resprouts, which exhibited increased photosynthesis (A), leaf conductance (g), quantum yield of PSII (ΔF/Fm′) and photochemical quenching (qP), were related to lower non-radiative dissipation of excess energy as indicated by 1 – (Fv′/Fm′). However, the fraction of energy remaining of that used in photo-chemistry or dissipated thermally in the PSII antennae was similar in resprouts and controls and was not affected by DTT, especially under high irradiance conditions. Zeaxanthin involvement in PSII protection operated in resprouts and controls since DTT induced the same kind of response (NPQ decrease) but was lower in resprouts. These chloro-phyll fluorescence results suggest the participation of some additional mechanism for energy dissipation. Light capture characteristics of the photosynthetic apparatus did not differ between resprouts and controls, and leaf age did not play a determining role in the differences observed.

Biochemical constrains limit the potential of the photochemical reflectance index as a predictor of effective quantum efficiency of photosynthesis during the winter spring transition in Jack pine seedlings

2009 ◽  
Vol 36 (11) ◽  
pp. 1016 ◽  
Author(s):  
Florian Busch ◽  
Norman P. A. Hüner ◽  
Ingo Ensminger
Keyword(s):  
Energy Dissipation ◽  
Quantum Efficiency ◽  
Xanthophyll Cycle ◽  
Physiological State ◽  
Jack Pine ◽  
Thermal Dissipation ◽  
Photochemical Quenching ◽  
Invasive Technique ◽  
Photochemical Reflectance Index ◽  
Leaf Reflectance

Leaf reflectance spectral measurements are an emerging non-invasive technique that can be used to derive the photochemical reflectance index (PRI) to assess the physiological state of plants from leaf to ecosystem level. Changes in PRI are associated with changes in the xanthophyll cycle activity and provide an estimate of changes in the effective photochemical quantum efficiency (ΦII) during the growing season. However, we hypothesised that the correlation between PRI and ΦII might be poor when the xanthophyll cycle is primed for sustained thermal dissipation of the light energy absorbed. To test our hypothesis, we studied the recovery of winter acclimated Jack pine (Pinus banksiana Lamb.) seedlings that were exposed to different simulated spring recovery treatments in controlled environments. Different growth temperatures and light intensities were used to dissect the effect of these two factors on chlorophyll fluorescence, pigment composition and leaf reflectance. ΦII showed a clear response to temperature whereas PRI was mostly affected by light intensity. In contrast, the de-epoxidation state of the xanthophyll cycle pigments was both temperature and light dependent. Our data suggest that zeaxanthin-independent non-photochemical quenching is employed to various degrees in the different treatments. As a result, within the limits of our experimental setup, PRI could not explain the variation in ΦII. This indicates that an improved understanding of the different energy quenching mechanisms is critical to accurately interpret the PRI signal under environmental conditions where the predominant mode of excess energy dissipation does not involve a dynamic operation of the xanthophyll cycle, but a sustained mechanism of energy dissipation.

scholarly journals Allosteric regulation of the light-harvesting system of photosystem II

2000 ◽  
Vol 355 (1402) ◽  
pp. 1361-1370 ◽  
Author(s):  
Peter Horton ◽  
Alexander V. Ruban ◽  
Mark Wentworth
Keyword(s):  
Photosystem Ii ◽  
Xanthophyll Cycle ◽  
Light Harvesting ◽  
Allosteric Regulation ◽  
Photochemical Quenching ◽  
Protein Subunit ◽  
Ps Ii ◽  
Non Photochemical Quenching

Non–photochemical quenching of chlorophyll fluorescence (NPQ) is symptomatic of the regulation of energy dissipation by the light–harvesting antenna of photosystem II (PS II). The kinetics of NPQ in both leaves and isolated chloroplasts are determined by the transthylakoid ΔpH and the de–epoxidation state of the xanthophyll cycle. In order to understand the mechanism and regulation of NPQ we have adopted the approaches commonly used in the study of enzyme–catalysed reactions. Steady–state measurements suggest allosteric regulation of NPQ, involving control by the xanthophyll cycle carotenoids of a protonationdependent conformational change that transforms the PS II antenna from an unquenched to a quenched state. The features of this model were confirmed using isolated light–harvesting proteins. Analysis of the rate of induction of quenching both in vitro and in vivo indicated a bimolecular second–order reaction; it is suggested that quenching arises from the reaction between two fluorescent domains, possibly within a single protein subunit. A universal model for this transition is presented based on simple thermodynamic principles governing reaction kinetics.

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