scholarly journals Efficient ultraviolet-light energy dissipation by an aromatic ketone

2010 ◽  
Vol 46 (5) ◽  
pp. 800-802 ◽  
Author(s):  
Abdelkarim El Moncef ◽  
M. Consuelo Cuquerella ◽  
Elena Zaballos ◽  
Carmen Ramírez de Arellano ◽  
Abdeslem Ben-Tama ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Ultraviolet Light ◽  
Light Energy ◽  
Aromatic Ketone

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.

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.

Effects of drought on light-energy dissipation mechanisms in high-light-acclimated, field-grown grapevines

2002 ◽  
Vol 29 (10) ◽  
pp. 1197 ◽  
Author(s):  
Hipólito Medrano ◽  
Josefina Bota ◽  
Anunciacion Abadía ◽  
Bartolomé Sampol ◽  
José M. Escalona ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Water Shortage ◽  
Co2 Assimilation ◽  
High Light ◽  
Light Energy ◽  
Thermal Dissipation ◽  
Severe Drought ◽  
Absorbed Energy ◽  
Dissipation Pattern ◽  
Effects Of Drought

The response of several light-energy dissipation mechanisms to water shortage was analysed in a 10-year study in field-grown, high-light-acclimated grapevines, and compared with those of greenhouse-grown, low-light-acclimated grapevines. Dissipation mechanisms, except leaf photochemistry, differ among cultivars and acclimate to the prevailing light conditions during growth. However, no additional acclimation to drought was observed. The dependence of the dissipation responses on stomatal conductance suggests that low CO2 availability in the chloroplasts during drought triggers variations in the energy dissipation pattern. In irrigated grapevines under high light, more than 50% of total absorbed energy is thermally dissipated. There is evidence that implicates the xanthophyll cycle as the main thermal dissipation processes. CO2 assimilation is the most important photochemical pathway of dissipation in irrigated plants, but is replaced by photorespiration when CO2 assimilation declines under mild drought. Under moderate to severe drought, both photosynthesis and photorespiration decline, and thermal dissipation increases to account for up to 90% of total dissipation. Involvement of other processes in light dissipation is minimal in grapevines. Even in severely-stressed leaves, the incidence of photoinhibition is very low, indicating that safe dissipation of absorbed energy is very effective in grapevines.

Effects of low temperature stress on excitation energy partitioning and photoprotection in Zea mays

2009 ◽  
Vol 36 (1) ◽  
pp. 37 ◽  
Author(s):  
Leonid V. Savitch ◽  
Alexander G. Ivanov ◽  
Loreta Gudynaite-Savitch ◽  
Norman P. A. Huner ◽  
John Simmonds
Keyword(s):  
Zea Mays ◽  
Energy Dissipation ◽  
Energy Partitioning ◽  
Light Energy ◽  
Dissipated Energy ◽  
Reaction Centre ◽  
Quenching Mechanism ◽  
Psii Photochemistry ◽  
Maize Plants ◽  
Recombination Pathway

Analysis of the partitioning of absorbed light energy within PSII into fractions utilised by PSII photochemistry (ΦPSII), thermally dissipated via ΔpH- and zeaxanthin-dependent energy quenching (ΦNPQ) and constitutive non-photochemical energy losses (Φf,D) was performed in control and cold-stressed maize (Zea mays L.) leaves. The estimated energy partitioning of absorbed light to various pathways indicated that the fraction of ΦPSII was twofold lower, whereas the proportion of thermally dissipated energy through ΦNPQ was only 30% higher, in cold-stressed plants compared with control plants. In contrast, Φf,D, the fraction of absorbed light energy dissipated by additional quenching mechanism(s), was twofold higher in cold-stressed leaves. Thermoluminescence measurements revealed that the changes in energy partitioning were accompanied by narrowing of the temperature gap (ΔTM) between S2/3QB− and S2QA− charge recombinations in cold-stressed leaves to 8°C compared with 14.4°C in control maize plants. These observations suggest an increased probability for an alternative non-radiative P680+QA− radical pair recombination pathway for energy dissipation within the reaction centre of PSII in cold-stressed maize plants. This additional quenching mechanism might play an important role in thermal energy dissipation and photoprotection when the capacity for the primary, photochemical (ΦPSII) and zeaxanthin-dependent non-photochemical quenching (ΦNPQ) pathways are thermodynamically restricted in maize leaves exposed to cold temperatures.

Effect of carbon/nitrogen ratio on carbohydrate metabolism and light energy dissipation mechanisms in Arabidopsis thaliana

2016 ◽  
Vol 105 ◽  
pp. 195-202 ◽  
Author(s):  
Thais Huarancca Reyes ◽  
Andrea Scartazza ◽  
Yu Lu ◽  
Junji Yamaguchi ◽  
Lorenzo Guglielminetti
Keyword(s):  
Arabidopsis Thaliana ◽  
Energy Dissipation ◽  
Carbohydrate Metabolism ◽  
Light Energy ◽  
Carbon Nitrogen Ratio ◽  
Nitrogen Ratio
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