Effects of Bleaching by Nitrogen Deficiency on the Quantum Yield of Photosystem II inSynechocystissp. PCC 6803 Revealed by Chl Fluorescence Measurements

AbstractPhotosynthesis, chlorophyll (Chl) fluorescence, and antioxidant enzymes were measured in the mulberry (Morus spp.) cultivars Da 10, Hongguo 2, Anza 1, and Taiwan 72C002, which were subjected to salinity and high-temperature stress (STS; 0.1%, 0.3%, and 0.5% NaCl concentrations, 34.5°C–40.5°C/27.8°C–29.2°C day/night temperatures). Control plants were watered with 1 L of full-strength Hoagland’s nutrient solution with no added NaCl. Net photosynthetic rate (P N), stomatal conductance (g s), and effective quantum yield of photosystem II photochemistry (ΦPSII) increased in Anza 1 and Taiwan 72C002 under 0.1% STS but decreased in Da 10 and Hongguo 2 compared with the control. However, all the above parameters, including Chl content, maximum quantum yield of photosystem II photochemistry (Fv/Fm), nonphotochemical quenching (NPQ), and maximum carboxylation velocity of Rubisco (V cmax, decreased in Taiwan 72C002, Honggua 2, and Da 10 under 0.3% and 0.5% STS, suggesting that photoinhibition occurred under severe STS. Under STS, there were no significant changes in P N, Fv/Fm, ΦPSII, ascorbate peroxidase (APX) activity, superoxide dismutase (SOD) activity, catalase activity, superoxide anion radical (O2−) content, malondialdehyde (MDA) content, soluble sugar content (SSC), and leaf biomass in Anza 1 even at 0.5% STS, showing that Anza 1 displays high resistance to STS. In addition, peroxidase activity was significantly higher in Anza 1 than in the other mulberry cultivars. Significant adverse effects of severe salinity on photosynthesis and Chl fluorescence parameters were observed in Da 10. Additionally, SOD, peroxidase, and APX activities were lower in Da 10, whereas O2− and MDA contents were higher in comparison with the other mulberry cultivars under 0.3% and 0.5% STS, suggesting that Da 10 had low resistance to STS. These results show that 0.1% STS had a positive effect on photosynthesis and Chl fluorescence parameters in Anza 1 and Taiwan 72C002, and higher peroxidase activity can to a certain extent explain the higher STS tolerance in Anza 1. Damages to DSM photosystems might be related to lower SOD, POD, and APX activities, which resulted in the accumulation of reactive oxygen species.

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Foliar photochemical processes and carbon metabolism under favourable and adverse winter conditions in a Mediterranean mixed forest, Catalonia (Spain)

Biogeosciences ◽

10.5194/bg-11-5657-2014 ◽

2014 ◽

Vol 11 (20) ◽

pp. 5657-5674 ◽

Cited By ~ 7

Author(s):

D. Sperlich ◽

C. T. Chang ◽

J. Peñuelas ◽

C. Gracia ◽

S. Sabaté

Keyword(s):

Quantum Yield ◽

Photosystem Ii ◽

Tree Species ◽

Cold Period ◽

Summer Drought ◽

Mild Winter ◽

Fluorescence Measurements ◽

Winter Conditions ◽

Evergreen Tree ◽

Wide Range

Abstract. Evergreen trees in the Mediterranean region must cope with a wide range of environmental stresses from summer drought to winter cold. The mildness of Mediterranean winters can periodically lead to favourable environmental conditions above the threshold for a positive carbon balance, benefitting evergreen woody species more than deciduous ones. The comparatively lower solar energy input in winter decreases the foliar light saturation point. This leads to a higher susceptibility to photoinhibitory stress especially when chilly (< 12 °C) or freezing temperatures (< 0 °C) coincide with clear skies and relatively high solar irradiances. Nonetheless, the advantage of evergreen species that are able to photosynthesize all year round where a significant fraction can be attributed to winter months, compensates for the lower carbon uptake during spring and summer in comparison to deciduous species. We investigated the ecophysiological behaviour of three co-occurring mature evergreen tree species (Quercus ilex L., Pinus halepensis Mill., and Arbutus unedo L.). Therefore, we collected twigs from the field during a period of mild winter conditions and after a sudden cold period. After both periods, the state of the photosynthetic machinery was tested in the laboratory by estimating the foliar photosynthetic potential with CO2 response curves in parallel with chlorophyll fluorescence measurements. The studied evergreen tree species benefited strongly from mild winter conditions by exhibiting extraordinarily high photosynthetic potentials. A sudden period of frost, however, negatively affected the photosynthetic apparatus, leading to significant decreases in key physiological parameters such as the maximum carboxylation velocity (Vc, max), the maximum photosynthetic electron transport rate (Jmax), and the optimal fluorometric quantum yield of photosystem II (Fv/Fm). The responses of Vc, max and Jmax were highly species specific, with Q. ilex exhibiting the highest and P. halepensis the lowest reductions. In contrast, the optimal fluorometric quantum yield of photosystem II (Fv/Fm) was significantly lower in A. unedo after the cold period. The leaf position played an important role in Q. ilex showing a stronger winter effect on sunlit leaves in comparison to shaded leaves. Our results generally agreed with the previous classifications of photoinhibition-tolerant (P. halepensis) and photoinhibition-avoiding (Q. ilex) species on the basis of their susceptibility to dynamic photoinhibition, whereas A. unedo was the least tolerant to photoinhibition, which was chronic in this species. Q. ilex and P. halepensis seem to follow contrasting photoprotective strategies. However, they seemed equally successful under the prevailing conditions exhibiting an adaptive advantage over A. unedo. These results show that our understanding of the dynamics of interspecific competition in Mediterranean ecosystems requires consideration of the physiological behaviour during winter which may have important implications for long-term carbon budgets and growth trends.

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Foliar photochemical processes and carbon metabolism under favourable and adverse winter conditions in a Mediterranean mixed forest, Catalonia (Spain)

Biogeosciences Discussions ◽

10.5194/bgd-11-9697-2014 ◽

2014 ◽

Vol 11 (6) ◽

pp. 9697-9759 ◽

Cited By ~ 2

Author(s):

D. Sperlich ◽

C. T. Chang ◽

J. Peñuelas ◽

C. Gracia ◽

S. Sabaté

Keyword(s):

Quantum Yield ◽

Photosystem Ii ◽

Tree Species ◽

Cold Period ◽

Summer Drought ◽

Mild Winter ◽

Fluorescence Measurements ◽

Winter Conditions ◽

Evergreen Tree ◽

Wide Range

Abstract. Evergreen trees in the Mediterranean region must cope with a wide range of environmental stresses from summer drought to winter cold. The mildness of Mediterranean winters can periodically lead to favourable environmental conditions above the threshold for a positive carbon balance, benefitting evergreen woody species more than deciduous ones. The comparatively lower solar energy input in winter decreases the foliar light saturation point. This leads to a higher susceptibility to photoinhibitory stress especially when chilly (< 12 °C) or freezing temperatures (< 0 °C) coincide with clear skies and relatively high solar irradiances. Nonetheless, the advantage of evergreen species that are able to photosynthesize all year round where a significant fraction can be attributed to winter months, compensates for the lower carbon uptake during spring and summer in comparison to deciduous species. We investigated the ecophysiological behaviour of three co-occurring mature evergreen tree species (Quercus ilex L., Pinus halepensis Mill., and Arbutus unedo L.) during a period of mild winter conditions and their responses to a sudden cold period. The state of the photosynthetic machinery in both periods was thus tested by estimating the foliar photosynthetic potential with CO2 response curves in parallel with chlorophyll fluorescence measurements. The studied evergreen tree species benefited strongly from mild winter conditions by exhibiting extraordinarily high photosynthetic potentials similar to those under spring conditions. A sudden period of frost, however, negatively affected the photosynthetic apparatus, leading to significant decreases in key physiological parameters such as the maximum carboxylation velocity (Vc, max), the maximum photosynthetic electron transport rate (Jmax), and the optimal fluorometric quantum yield of photosystem II (Fv/Fm). This change persisted for several weeks after the cold period despite the recovery of the temperature to the conditions previous to the frost event. The responses of Vc, max and Jmax were highly species-specific, where Q. ilex exhibited the highest and P. halepensis the lowest reductions. In contrast, the optimal fluorometric quantum yield of photosystem II (Fv/Fm) was significantly lower in A. unedo after the cold period. The leaf position played an important role in Q. ilex showing a comparatively stronger winter effect on sunlit leaves. Our results generally agreed with the previous classifications of photoinhibition-avoiding (P. halepensis) and photoinhibition-tolerant (Q. ilex) species on the basis of their susceptibility to dynamic photoinhibition, whereas A. unedo was the least tolerant to photoinhibition, which was chronic in this species. Q. ilex and P. halepensis seem to follow contrasting photoprotective strategies which are, however, equally successful under the prevailing conditions exhibiting an adaptive advantage over A. unedo in our study site. These results show that our understanding of the dynamics of interspecific competition in Mediterranean ecosystems requires consideration of the physiological behaviour during winter which may have important implications for long-term carbon budgets and growth trends.

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Faculty Opinions recommendation of The cyanobacterial homologue of HCF136/YCF48 is a component of an early photosystem II assembly complex and is important for both the efficient assembly and repair of photosystem II in Synechocystis sp. PCC 6803.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.7466956.7759054 ◽

2011 ◽

Author(s):

Dario Leister

Keyword(s):

Photosystem Ii ◽

Synechocystis Sp ◽

Pcc 6803

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Chlorophyll Fluorescence Measurements in Arabidopsis Wild-type and Photosystem II Mutant Leaves

BIO-PROTOCOL ◽

10.21769/bioprotoc.1532 ◽

2015 ◽

Vol 5 (14) ◽

Cited By ~ 3

Author(s):

Iris Steinberger ◽

Felix Egidi ◽

Anja Schneider

Keyword(s):

Chlorophyll Fluorescence ◽

Photosystem Ii ◽

Wild Type ◽

Fluorescence Measurements

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Nitrogen and Phosphorus Addition to Soil Improves Seed Yield, Foliar Stomatal Conductance, and the Photosynthetic Response of Rapeseed (Brassica napus L.)

Agriculture ◽

10.3390/agriculture11060483 ◽

2021 ◽

Vol 11 (6) ◽

pp. 483

Author(s):

Esmaeil Zangani ◽

Kamran Afsahi ◽

Farid Shekari ◽

Eileen Mac Sweeney ◽

Andrea Mastinu

Keyword(s):

Stomatal Conductance ◽

Quantum Yield ◽

Photosystem Ii ◽

Chlorophyll Content ◽

Seed Yield ◽

Nitrogen Application ◽

Flowering Stage ◽

Nitrogen And Phosphorus ◽

Brassica Napus L ◽

Phosphorus Levels

The effects of nitrogen and phosphorus levels on the physiological traits, yield, and seed yield of rapeseed (Brassica napus L.), were studied in a farm research project of Zanjan University. Three levels of nitrogen (0, 100, and 200 kg/ha) and three levels of phosphorus (0, 75, and 150 kg/ha) were considered. The results showed that an increase in nitrogen level caused an increase in the leaf chlorophyll content so that the application of 200 kg/ha of nitrogen increased the chlorophyll content of the leaves until the mid-grain filling stage. Nitrogen application lowered leaf stomatal conductance in the early flowering stage whereas the stomatal conductance was increased during the late flowering stage. Nitrogen application (100 and 200 kg/ha) also increased the quantum yield of photosystem II. On the other hand, with the application of 150 kg/ha and 75 kg/ha of phosphorus, the leaf stomatal conductance and the quantum yield of photosystem II in the early flowering stage increased respectively. The results showed that the application of 200 kg/ha of nitrogen and 75 kg/ha of phosphorus significantly increased seed and oil yield compared to the control. In addition, the number of siliques per plant and the weight of 1000 seeds showed an increasing trend that was affected by nitrogen and phosphorus levels. This study demonstrated that nitrogen enhanced the chlorophyll content, leaf area, and consequently, the quantum yield of photosystem II. Nitrogen also augmented the seed filling duration, seed yield, and oil yield by increasing gas exchange. As a result, the application of 100 kg/ha of nitrogen together with 75 kg/ha phosphorus showed the greatest effect on the qualitative and quantitative yield of rapeseed. However, the application of 200 kg/ha of nitrogen alone or in combination with different levels of phosphorus did not significantly increase many of the studied traits.

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