scholarly journals Limitation of CO2 Assimilation and Regulation of Benson-Calvin Cycle Activity in Barley Leaves in Response to Changes in Irradiance, Photoinhibition, and Recovery

1989 ◽  
Vol 91 (4) ◽  
pp. 1562-1568 ◽  
Author(s):  
Marie Dujardyn ◽  
Christine H. Foyer
Keyword(s):  
Calvin Cycle ◽  
Co2 Assimilation ◽  
Barley Leaves

A simple dynamic model of photosynthesis in oak leaves: coupling leaf conductance and photosynthetic carbon fixation by a variable intracellular CO2 pool

2004 ◽  
Vol 31 (12) ◽  
pp. 1195 ◽  
Author(s):  
Steffen M. Noe ◽  
Christoph Giersch
Keyword(s):  
Carbon Fixation ◽  
Calvin Cycle ◽  
Target Function ◽  
Vapour Pressure Deficit ◽  
Co2 Assimilation ◽  
Leaf Conductance ◽  
Co2 Partial Pressure ◽  
Sink Term ◽  
Essential Components ◽  
Oak Leaves

Modelling the diurnal course of photosynthesis in oak leaves (Quercus robur L.) requires appropriate description of the dynamics of leaf photosynthesis of which diurnal variations in leaf conductance and in CO2 assimilation are essential components. We propose and analyse a simple photosynthesis model with three variables: leaf conductance (gs), the CO2 partial pressure inside the leaf (pi), and a pool of Calvin cycle intermediates (aps). The environmental factors light (I) and vapour pressure deficit (VPD) are used to formulate a target function G(I, VPD) from which the actual leaf conductance is calculated. Using this gs value and a CO2 consumption term representing CO2 fixation, a differential equation for pi is derived. Carboxylation corresponds to the sink term of the pi pool and is assumed to be feedback-inhibited by aps. This simple model is shown to produce reasonable to excellent fits to data on the diurnal time courses of photosythesis, pi and gs sampled for oak leaves.

An intrinsically disordered protein, CP12: jack of all trades and master of the Calvin cycle

2012 ◽  
Vol 40 (5) ◽  
pp. 995-999 ◽  
Author(s):  
Brigitte Gontero ◽  
Stephen C. Maberly
Keyword(s):  
Amino Acids ◽  
Stress Responses ◽  
Intrinsically Disordered Proteins ◽  
Calvin Cycle ◽  
Intrinsically Disordered Protein ◽  
Disulfide Bridge ◽  
Co2 Assimilation ◽  
Disordered Proteins ◽  
Dimensional Structure ◽  
Intrinsically Disordered

Many proteins contain disordered regions under physiological conditions and lack specific three-dimensional structure. These are referred to as IDPs (intrinsically disordered proteins). CP12 is a chloroplast protein of approximately 80 amino acids and has a molecular mass of approximately 8.2–8.5 kDa. It is enriched in charged amino acids and has a small number of hydrophobic residues. It has a high proportion of disorder-promoting residues, but has at least two (often four) cysteine residues forming one (or two) disulfide bridge(s) under oxidizing conditions that confers some order. However, CP12 behaves like an IDP. It appears to be universally distributed in oxygenic photosynthetic organisms and has recently been detected in a cyanophage. The best studied role of CP12 is its regulation of the Calvin cycle responsible for CO2 assimilation. Oxidized CP12 forms a supramolecular complex with two key Calvin cycle enzymes, GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and PRK (phosphoribulokinase), down-regulating their activity. Association–dissociation of this complex, induced by the redox state of CP12, allows the Calvin cycle to be inactive in the dark and active in the light. CP12 is promiscuous and interacts with other enzymes such as aldolase and malate dehydrogenase. It also plays other roles in plant metabolism such as protecting GAPDH from inactivation and scavenging metal ions such as copper and nickel, and it is also linked to stress responses. Thus CP12 seems to be involved in many functions in photosynthetic cells and behaves like a jack of all trades as well as being a master of the Calvin cycle.

scholarly journals CO2 Assimilation, Photosynthetic Enzymes, and Carbohydrates of Grape Leaves (Vitis labrusca L. cv. Concord) in Response to Iron Supply

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 826D-827
Author(s):  
Brandon R. Smith* ◽  
Li-Song Chen ◽  
Lailiang Cheng
Keyword(s):  
Calvin Cycle ◽  
Sucrose Phosphate Synthase ◽  
Co2 Assimilation ◽  
Carbon Export ◽  
Photosynthetic Enzymes ◽  
Hydroxyphenylacetic Acid ◽  
Key Enzyme ◽  
The Difference ◽  
One Year ◽  
Assimilation Capacity

Own-rooted one-year-old `Concord' grapevines were fertigated twice weekly for 11 weeks with 1, 10, 20, 50, OR 100 μmol iron (Fe) from ferric ethylenediamine di (o-hydroxyphenylacetic) acid in a complete nutrient solution. As Fe supply increased, leaf total Fe content did not change, whereas active Fe (extracted by 2, 2'-dipyridyl) and total chlorophyll content increased curvilinearly. CO2 assimilation and stomatal conductance increased curvilinearly with increasing active Fe, whereas intercellular CO2 concentrations decreased linearly. Activities of key Calvin cycle enzymes, Rubisco, NADP-glyceraldehyde-3-phosphate dehydrogenase, phosphoribulokinase, stromal fructose-1,6-bisphosphatase (FBPase), and a key enzyme in sucrose synthesis, cytosolic FBPase, all increased linearly with increasing active Fe. No difference was found in the activities of ADP-glucose pyrophosphorylase and sucrose phosphate synthase of leaves between the lowest and the highest treatments, whereas slightly lower activities were observed in the middle Fe treatments. Content of 3-phosphoglycerate increased curvilinearly with increased active Fe, whereas glucose-6-phosphate and fructose-6-phosphate did not change. Glucose, fructose, sucrose, starch, and total non-structural carbohydrates at both dusk and pre-dawn increased with increasing active Fe. Carbon export from starch breakdown during the night, calculated as the difference between dusk and predawn levels, increased as active Fe increased. In conclusion, Fe limitation reduces the activities of Rubisco and other photosynthetic enzymes, and hence CO2 assimilation capacity. Fe-deficient grapevines have lower concentrations of non-structural carbohydrates in source leaves, and therefore, are source limited.

scholarly journals Adjustment of Photosynthetic and Antioxidant Activities to Water Deficit Is Crucial in the Drought Tolerance of Lolium multiflorum/Festuca arundinacea Introgression Forms

2020 ◽  
Vol 21 (16) ◽  
pp. 5639
Author(s):  
Katarzyna Lechowicz ◽  
Izabela Pawłowicz ◽  
Dawid Perlikowski ◽  
Magdalena Arasimowicz-Jelonek ◽  
Sara Blicharz ◽  
...  
Keyword(s):  
Drought Tolerance ◽  
Water Deficit ◽  
Festuca Arundinacea ◽  
Antioxidant Activities ◽  
Lolium Multiflorum ◽  
Calvin Cycle ◽  
Co2 Assimilation ◽  
Intrinsic Water Use Efficiency ◽  
Use Efficiency ◽  
Fructose 1,6 Bisphosphate

Lolium multiflorum/Festuca arundinacea introgression forms have been proved several times to be good models to identify key components of grass metabolism involved in the mechanisms of tolerance to water deficit. Here, for the first time, a relationship between photosynthetic and antioxidant capacities with respect to drought tolerance of these forms was analyzed in detail. Two closely related L. multiflorum/F. arundinacea introgression forms distinct in their ability to re-grow after cessation of prolonged water deficit in the field were selected and subjected to short-term drought in pots to dissect precisely mechanisms of drought tolerance in this group of plants. The studies revealed that the form with higher drought tolerance was characterized by earlier and higher accumulation of abscisic acid, more stable cellular membranes, and more balanced reactive oxygen species metabolism associated with a higher capacity of the antioxidant system under drought conditions. On the other hand, both introgression forms revealed the same levels of stomatal conductance, CO2 assimilation, and consequently, intrinsic water use efficiency under drought and recovery conditions. However, simultaneous higher adjustment of the Calvin cycle to water deficit and reduced CO2 availability, with respect to the accumulation and activity of plastid fructose-1,6-bisphosphate aldolase, were clearly visible in the form with higher drought tolerance.

Greenhouse and field cucumber genotypes use different mechanisms to protect against dark chilling

2004 ◽  
Vol 31 (12) ◽  
pp. 1215 ◽  
Author(s):  
Yan-Hong Zhou ◽  
Li-Feng Huang ◽  
Yao-Shun Du ◽  
Jing-Quan Yu
Keyword(s):  
Calvin Cycle ◽  
Photosynthetic Electron Transport ◽  
Co2 Assimilation ◽  
Photochemical Quenching ◽  
Genotypic Differences ◽  
Diurnal Changes ◽  
Cucumis Sativus L ◽  
Photosynthetic Gas Exchange ◽  
Protection Mechanism ◽  
Psii Photochemistry

Diurnal changes in photosynthetic gas exchange and chlorophyll fluorescence were measured after two consecutive night chills to reveal the photosynthetic characteristics and the mechanism of photoprotection in a greenhouse genotype Jinyou No. 3 (GH), and in a field genotype Jinyan No. 4 (OF) of cucumber (Cucumis sativus L.). Both genotypes showed inhibition of CO2 assimilation immediately after the dark chill, with OF exhibiting a greater reduction. Dark chilling had little effect on stomatal limitation (l) and RuBP regeneration (Jmax) but significantly decreased maximum carboxylation velocity of Rubisco (Vcmax). The reduced capacity for CO2 fixation in the Calvin cycle induced a downstream regulation of PSII photochemistry, a mechanism that regulates the photosynthetic electron transport to match the lower demand for ATP and NADPH in the stroma of chloroplasts. The reduced quantum efficiency of PSII photochemistry was mainly due to reductions both in the photochemical quenching coefficient (qP) and in the efficiency of excitation energy capture by open PSII reaction centres (Fv′ / Fm′) for OF, but only to the latter for GH. Night chills resulted in an enhanced photorespiration proportion in GH and an O2-dependent alternative electron flux in OF, which served as protective mechanisms for the two varieties. These results showed that there are genotypic differences in the limitation factor for CO2 assimilation and in photo-protection mechanism to night chill in cucumber.

Metabolism of glycolic acid-1-14C in barley leaves with or without added CO2

1971 ◽  
Vol 49 (2) ◽  
pp. 299-302 ◽  
Author(s):  
Imre A. Tamàs ◽  
R. G. S. Bidwell
Keyword(s):  
Hordeum Vulgare ◽  
Glycolic Acid ◽  
Calvin Cycle ◽  
Sucrose Synthesis ◽  
Hordeum Vulgare L ◽  
Barley Leaves

Detached primary leaves of barley (Hordeum vulgare L. var. Dayton) were supplied with glycolate-1 -14C in light or darkness with or without CO2, and the radioactivity of soluble metabolites and evolved CO2 was measured at intervals. The results of these experiments suggest that exogenously supplied glycolate is metabolized by two distinct pathways in illuminated leaves. It may be converted to sucrose outside the chloroplasts, presumably via the glycolate pathway. Alternatively glycolate carbon, through some product of its metabolism, enters the chloroplasts and becomes incorporated into intermediates of the Calvin cycle, from which photorespired CO2 is derived. Endogenous glycolate, originating from Calvin cycle intermediates, may leave the chloroplasts and become a substrate for sucrose synthesis. Exchange of carbon therefore appears to take place between the Calvin cycle inside and the glycolate pathway outside the chloroplasts. This exchange gives a net flow of carbon out of the chloroplasts during photosynthetic CO2 fixation. However, at low external CO2 concentration the flow of carbon from the glycolate pathway into the Calvin cycle in chloroplasts is greatly enhanced, providing substrate for CO2 production. Exogenous glycolate apparently does not directly enter the site of CO2 production in light. However, it is converted to CO2 in darkness, without the participation of the Calvin cycle.

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