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.

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.

Mangrove Photosynthesis: Response to High-Irradiance Stress

1988 ◽  
Vol 15 (2) ◽  
pp. 43 ◽  
Author(s):  
O Bjorkman ◽  
B Demmig ◽  
TJ Andrews
Keyword(s):  
Energy Dissipation ◽  
Photosystem Ii ◽  
Energy Conversion ◽  
O2 Evolution ◽  
Photon Yield ◽  
Mangrove Species ◽  
Reaction Centres ◽  
Fluorescence Characteristics ◽  
Shade Leaves ◽  
Sun Leaves

Efficiencies of photosynthetic energy conversion were determined in sun and shade leaves of several mangrove species, growing in an open intertidal habitat in North Queensland, by measuring the maximum photon yield of O2 evolution and 77K chlorophyll fluorescence characteristics. Preliminary meas- urements confirmed that mangrove leaves have low water potentials, low stomatal conductances and low light-saturated CO2 exchange rates. Mangrove sun leaves therefore received a very large excess of excitation energy. Mangrove shade leaves had as high a photon yield of O2 evolution as non-mangrove leaves and their fluorescence characteristics were normal, showing that the energy conversion efficiency was unaffected by the high salinity. Mangrove sun leaves had markedly depressed photon yields and fluorescence was severely quenched showing that the efficiency of the photochemistry of photosystem II was reduced. The efficiency of energy conversion decreased with an increased radiation receipt. No such depression was detected in sun leaves of non-mangrove species growing in adjacent non-saline sites. Shading of man- grove sun leaves resulted in an increase in the efficiency of energy conversion but, in most species, more than 1 week was required for these leaves to reach the efficiency of shade leaves. Leaves exposed to direct sunlight had somewhat higher efficiencies in mangrove plants cultivated in 10% seawater as compared with full-strength seawater but the salinity of the culture solution had little effect on the increase in the efficiency upon shading. Field and laboratory fluorescence measurements indicated that the reduced efficiency of energy conversion in mangrove sun leaves resulted from a large increase in the rate constant for radiationless energy dissipation in the antenna chlorophyll rather than from damage to the photosystem II reaction centres. We propose that this increase in radiationless energy dissipation serves to protect the reaction centres against damage by excessive excitation.

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.

scholarly journals Carbon gain optimization in five broadleaf deciduous trees in response to light variation within the crown: correlations among morphological, anatomical and physiological leaf traits

2015 ◽  
Vol 74 (1) ◽  
pp. 71-94 ◽  
Author(s):  
Rosangela Catoni ◽  
Loretta Gratani ◽  
Francesco Sartori ◽  
Laura Varone ◽  
Mirko U. Granata
Keyword(s):  
Phenotypic Plasticity ◽  
Deciduous Forest ◽  
Light Variation ◽  
Stress Factors ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Carbon Gain ◽  
Deciduous Species ◽  
Shade Leaves ◽  
Sun Leaves

AbstractLeaf trait variations in five deciduous species (Quercus robur, Corylus avellana, Populus alba, Acer campestre, Robinia pseudoacacia) growing in an old broadleaf deciduous forest in response to light variation within the tree crown was analyzed. Net photosynthetic rate (PN), leaf respiration rate (R) and the photosynthetic nitrogen use efficiency were, on average, more than 100% higher in sun than in shade leaves. A. campestre and C. avellana sun leaves had the highest specific leaf area (SLA, 156.0 ± 17.9 cm2 g-1) and the lowest total leaf thickness (L, 101.9 ± 8.8 μm) underlining their shade-tolerance. Among the shade-intolerant species (Q. robur, P. alba and R. pseudoacacia), Q. robur had the lowest SLA and the highest L in sun leaves (130.6 ± 10.0 cm2 g-1 and 160.8 ± 9.6 μm, respectively) since shade-intolerant species typically have thicker leaves. The higher PN decrease in respect to R decrease from sun to shade leaves attested the higher sensitivity of PN than R to light variations within the crown. This determined a 69% lower R/PN in sun than in shade leaves. This result is further attested by the significant correlation between PN and the relative photosynthetic photon flux density. The shade-tolerant species have a 76% higher R/PN ratio than the shade-intolerant ones. The measured leaf phenotypic plasticity (PI = 0.35) was in the range of broadleaf deciduous species. Plasticity is a key trait useful to quantify plant response to environmental stimuli. It is defined as the ability of a genotype to produce different phenotypes depending on the environment. Among the considered species, Q. robur showed the highest PI (0.39) and P. alba the lowest (0.29). Knowledge on phenotypic plasticity is important in making hypotheses about the dynamics of the studied forest in consideration of environmental stress factors, including invasive species competition and global climate change.

Inhibition of Photosystems I and II in Chilling-Sensitive and Chilling-Tolerant Plants under Light and Low-Temperature Stress

1999 ◽  
Vol 54 (9-10) ◽  
pp. 645-657 ◽  
Author(s):  
Carina Barth ◽  
G. Heinrich Krause
Keyword(s):  
Low Temperature ◽  
Xanthophyll Cycle ◽  
Spinacia Oleracea ◽  
Light Stress ◽  
Fluorescence Emission ◽  
Early Spring ◽  
Psii Efficiency ◽  
Chl A ◽  
Leaf Discs

The responses of photosystems (PS) I and II to light stress at 4 °C and 20 °C were studied in leaf discs from three chilling-sensitive plant species, Cucumis sativus, Cucurbita maxima and Nicotiana tabacum, and in the chilling-tolerant Spinacia oleracea. The chilling-sensitive plants were grown at 24 °C under 80 -120 μmol photons m-2 s-1 (Cucumis and Cucurbita) or 30 μmol photons m-2 s-1 (Nicotiana). Spinacia was cultivated outdoors during winter and early spring. The P700 absorbance change around 820 nm served as a relative measure of PSI activity. The potential efficiency of PSII was determined in dark-adapted leaf discs by means of the ratio of variable to maximum chlorophyll (Chl) a fluorescence emission (Fv/Fᴍ). In Cucurbita, Nicotiana and Spinacia, PSI was not or only slightly inhibited by 2 h illumination with 200 μmol m-2 s-1 at 4 °C or with 2000 μmol m-2 s-1 at 20 °C. In leaves of Cucurbita and Nicotiana, exposure to 2000 μmol photons m-2 s-1 at 4 °C resulted in a decline in PSI activity and potential PSII efficiency approximately to the same extent (about 50% within 2 h). In contrast, in Cucumis, both moderate and high light at low temperature caused a PSI inhibition that proceeded considerably faster than the decline in PSII efficiency. Such preferential photoinhibition of PSI was not observed in the other three species tested. In Spinacia, a lower susceptibility of PSI and PSII to photoinhibition at 4 °C was associated with a faster de-epoxidation kinetics of violaxanthin, as compared to the three chilling-sensitive species. In addition, leaves of Spinacia were characterized by a significantly larger pool of xanthophyll-cycle pigments and a higher content of β-carotene based on Chi a+b. When leaves of Cucurbita were preincubated with methylviologen, which catalyzes formation of superoxide anion radicals at the acceptor side of PSI, the decline in potential PSII efficiency under 2000 μmol photons m-2 s-1 at 20 °C and 4 °C was strongly enhanced, whereas the P700 signal was less affected. Our data demonstrate that in the species tested, PSI may be inhibited in vivo besides PSII under light stress, but preferential photoinhibition of PSI is not a general phenomenon in chilling-sensitive plants. At low temperatures, a reduced function of the xanthophyll cycle and of the antioxidative scavenging system might account for enhanced PSI and PSII inhibition in vivo

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