scholarly journals Doubling the CO2 Concentration Enhanced the Activity of Carbohydrate-Metabolism Enzymes, Source Carbohydrate Production, Photoassimilate Transport, and Sink Strength for Opuntia ficus-indica

1996 ◽  
Vol 110 (3) ◽  
pp. 893-902 ◽  
Author(s):  
N. Wang ◽  
P. S. Nobel
Keyword(s):  
Carbohydrate Metabolism ◽  
Co2 Concentration ◽  
Sink Strength ◽  
Opuntia Ficus Indica ◽  
Metabolism Enzymes

scholarly journals Activity of Energy and Carbohydrate Metabolism Enzymes in the Juvenile Pink Salmon Oncorhynchus gorbuscha (Walb.) during the Transition from Freshwater to a Marine Environment

2021 ◽  
Vol 48 (5) ◽  
pp. 546-554
Author(s):  
M. V. Churova ◽  
N. S. Shulgina ◽  
M. Yu. Krupnova ◽  
D. A. Efremov ◽  
N. N. Nemova
Keyword(s):  
Carbohydrate Metabolism ◽  
Marine Environment ◽  
Pentose Phosphate Pathway ◽  
Anaerobic Metabolism ◽  
Pink Salmon ◽  
Atp Synthesis ◽  
Pentose Phosphate ◽  
Oncorhynchus Gorbuscha ◽  
Biochemical Adaptation ◽  
Metabolism Enzymes

Abstract Biochemical adaptations of energy metabolism and some pathways of glucose oxidation during a change in salinity of the environment in larvae and smolts of the pink salmon Oncorhynchus gorbuscha (Walb.) inhabiting the White Sea were studied. We assayed the activity of energy and carbohydrate metabolism enzymes (cytochrome c oxidase (COХ), lactate dehydrogenase (LDH), glucose-6-phosphate dehydrogenase (G6PDH), 1-glycerophosphate dehydrogenase (1-GPDH), and aldolase) in pink salmon larvae in a short-term aquarium experiment and in pink salmon smolts in a long-term cage experiment simulating the transition of juveniles from freshwater to a marine environment. A decrease in the activity of COX, LDH, 1‑GPDH, and aldolase already in the first hour after the transfer of larvae to seawater was shown. Smolts kept in the estuary and in the sea had low levels of activity of 1-GPDH and aldolase in comparison with individuals from the river. Most likely, in the salmon juveniles studied, there was a redistribution of carbohydrates between the reactions of aerobic and anaerobic metabolism in favor of anaerobic ATP synthesis. No changes in the enzyme activity of the pentose phosphate pathway, G-6-PDH, were found in either larvae or smolts compared with the individuals kept in freshwater. Maintenance of the required levels of anaerobic metabolism and of the pentose phosphate pathway is probably one of the mechanisms of biochemical adaptation of pink salmon to changes in salinity.

scholarly journals The Crosstalk of Melatonin and Hydrogen Sulfide Determines Photosynthetic Performance by Regulation of Carbohydrate Metabolism in Wheat under Heat Stress

Plants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1778 ◽  
Author(s):  
Noushina Iqbal ◽  
Mehar Fatma ◽  
Harsha Gautam ◽  
Shahid Umar ◽  
Adriano Sofo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Sulfide ◽  
Heat Stress ◽  
Carbohydrate Metabolism ◽  
Soluble Sugars ◽  
Photosynthetic Apparatus ◽  
Time Duration ◽  
H2o2 Content ◽  
Metabolism Enzymes ◽  
Regulation Of Carbohydrate Metabolism

Photosynthesis is a pivotal process that determines the synthesis of carbohydrates required for sustaining growth under normal or stress situation. Stress exposure reduces the photosynthetic potential owing to the excess synthesis of reactive oxygen species that disturb the proper functioning of photosynthetic apparatus. This decreased photosynthesis is associated with disturbances in carbohydrate metabolism resulting in reduced growth under stress. We evaluated the importance of melatonin in reducing heat stress-induced severity in wheat (Triticum aestivum L.) plants. The plants were subjected to 25 °C (optimum temperature) or 40 °C (heat stress) for 15 days at 6 h time duration and then developed the plants for 30 days. Heat stress led to oxidative stress with increased production of thiobarbituric acid reactive substances (TBARS) and hydrogen peroxide (H2O2) content and reduced accrual of total soluble sugars, starch and carbohydrate metabolism enzymes which were reflected in reduced photosynthesis. Application of melatonin not only reduced oxidative stress through lowering TBARS and H2O2 content, augmenting the activity of antioxidative enzymes but also increased the photosynthesis in plant and carbohydrate metabolism that was needed to provide energy and carbon skeleton to the developing plant under stress. However, the increase in these parameters with melatonin was mediated via hydrogen sulfide (H2S), as the inhibition of H2S by hypotaurine (HT; H2S scavenger) reversed the ameliorative effect of melatonin. This suggests a crosstalk of melatonin and H2S in protecting heat stress-induced photosynthetic inhibition via regulation of carbohydrate metabolism.

scholarly journals High sink strength prevents photosynthetic down-regulation in cassava grown at elevated CO2 concentration

2020 ◽  
Author(s):  
Ursula M Ruiz-Vera ◽  
Amanda P De Souza ◽  
Michael R Ament ◽  
Roslyn M Gleadow ◽  
Donald R Ort
Keyword(s):  
Elevated Co2 ◽  
Leaf Tissue ◽  
Co2 Enrichment ◽  
Co2 Concentration ◽  
Cultivar Differences ◽  
Sink Strength ◽  
Down Regulation ◽  
Tropical Regions ◽  
Free Air ◽  
Intrinsic Water Use Efficiency

Abstract Cassava has the potential to alleviate food insecurity in many tropical regions, yet few breeding efforts to increase yield have been made. Improved photosynthetic efficiency in cassava has the potential to increase yields, but cassava roots must have sufficient sink strength to prevent carbohydrates from accumulating in leaf tissue and suppressing photosynthesis. Here, we grew eight farmer-preferred African cassava cultivars under free-air CO2 enrichment (FACE) to evaluate the sink strength of cassava roots when photosynthesis increases due to elevated CO2 concentrations ([CO2]). Relative to the ambient treatments, elevated [CO2] treatments increased fresh (+27%) and dry (+37%) root biomass, which was driven by an increase in photosynthesis (+31%) and the absence of photosynthetic down-regulation over the growing season. Moreover, intrinsic water use efficiency improved under elevated [CO2] conditions, while leaf protein content and leaf and root cyanide concentrations were not affected. Overall, these results suggest that higher cassava yields can be expected as atmospheric [CO2] increases over the coming decades. However, there were cultivar differences in the partitioning of resources to roots versus above-grown biomass; thus, the particular responses of each cultivar must be considered when selecting candidates for improvement.

scholarly journals Carbon flux to woody tissues in a beech/spruce forest during summer and in response to chronic O<sub>3</sub> exposure

2011 ◽  
Vol 8 (11) ◽  
pp. 3127-3138 ◽  
Author(s):  
W. Ritter ◽  
C. P. Andersen ◽  
R. Matyssek ◽  
T. E. E. Grams
Keyword(s):  
Stable Carbon Isotope ◽  
Co2 Concentration ◽  
Sink Strength ◽  
Co2 Efflux ◽  
Coarse Roots ◽  
Coarse Root ◽  
Free Air ◽  
Adult Trees ◽  
Stem Co2 Efflux ◽  
Turn Over

Abstract. The present study compares the dynamics in carbon (C) allocation of adult deciduous beech (Fagus sylvatica) and evergreen spruce (Picea abies) during summer and in response to seven-year-long exposure with twice-ambient ozone (O3) concentrations (2 × O3). Focus was on the respiratory turn-over and translocation of recent photosynthates at various positions along the stems, coarse roots and soils. The hypotheses tested were that (1) 2 × O3 decreases the allocation of recent photosynthates to CO2 efflux of stems and coarse roots of adult trees, and that (2) according to their different O3 sensitivities this effect is stronger in beech than in spruce. Labeling of whole tree canopies was applied by releasing 13C depleted CO2 (δ13C of −46.9‰) using a free-air stable carbon isotope approach. Canopy air δ13C was reduced for about 2.5 weeks by ca. 8‰ in beech and 6‰ in spruce while the increase in CO2 concentration was limited to about 110 μl l−1 and 80 μl l−1, respectively. At the end of the labeling period, δ13C of stem CO2 efflux and phloem sugars was reduced to a similar extend by ca. 3–4‰ (beech) and ca. 2–3‰ (spruce). The fraction of labeled C (fE,new) in stem CO2 efflux amounted to 0.3 to 0.4, indicating slow C turnover of the respiratory supply system in both species. Elevated O3 slightly stimulated the allocation of recently fixed photosynthates to stem and coarse root respiration in spruce (rejection of hypothesis I for spruce), but resulted in a significant reduction in C flux in beech (acceptance of hypotheses I and II). The distinct decrease in C allocation to beech stems indicates the potential of chronic O3 stress to substantially mitigate the C sink strength of trees on the long-term scale.

scholarly journals The Crosstalk of Melatonin and Hydrogen Sulfide Determines Photosynthetic Performance by Regulation of Carbohydrate Metabolism in Wheat under Heat Stress

2021 ◽  
Author(s):  
Noushina Iqbal ◽  
Mehar Fatma ◽  
Harsha Gautam ◽  
Shahid Umar ◽  
Adriano Sofo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hydrogen Sulfide ◽  
Heat Stress ◽  
Carbohydrate Metabolism ◽  
Soluble Sugars ◽  
Photosynthetic Apparatus ◽  
Time Duration ◽  
H2o2 Content ◽  
Metabolism Enzymes ◽  
Regulation Of Carbohydrate Metabolism

Photosynthesis is a pivotal process that determines the synthesis of carbohydrates required for sustaining growth under normal or stress situation. Stress exposure reduces the photosynthetic potential owing to the excess synthesis of reactive oxygen species that disturb the proper functioning of photosynthetic apparatus. This decreased photosynthesis is associated with disturbances in carbohydrate metabolism resulting in reduced growth under stress. We evaluated the importance of melatonin in reducing heat stress-induced severity in wheat plants (Triticum aestivum L.). The plants were subjected to 25 ˚C (optimum temperature) or 40 ˚C (heat stress) for 15 days at 6 hours time duration and then developed the plants for 30 days. Heat stress led to oxidative stress with increased production of TBARS and H2O2 content and reduced accrual of total soluble sugars, starch and carbohydrate metabolism enzymes which are reflected in reduced photosynthesis. Application of melatonin not only reduced oxidative stress through lowering TBARS and H2O2 content, through augmenting the activity of antioxidative enzymes but also increased the photosynthesis in plant and carbohydrate metabolism that is needed to provide energy and carbon skeleton to the developing plant under stress. However, the increase in these parameters with melatonin was mediated via hydrogen sulfide (H2S), as the inhibition of H2S by hypotaurine (HT; H2S inhibitor) reversed the ameliorative effect of melatonin. This suggests a crosstalk of melatonin and H2S in protecting heat stress-induced photosynthetic inhibition via regulation of carbohydrate metabolism.

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