Protection of photosynthetic O2 evolution against heat inactivation: the role of chloride, pH and coupling status

1988 ◽  
Vol 15 (2) ◽  
pp. 143-152 ◽  
Author(s):  
Christa Critchley ◽  
Renu Khanna Chopra
Keyword(s):  
Heat Inactivation ◽  
O2 Evolution ◽  
Photosynthetic O2 Evolution

Low temperature effects on grapevine photosynthesis: the role of inorganic phosphate

2004 ◽  
Vol 31 (8) ◽  
pp. 789 ◽  
Author(s):  
Luke Hendrickson ◽  
Wah Soon Chow ◽  
Robert T. Furbank
Keyword(s):  
Low Temperature ◽  
Carbon Assimilation ◽  
O2 Evolution ◽  
Vitis Vinifera L ◽  
Regulatory Processes ◽  
Photosynthetic O2 Evolution ◽  
Grapevine Leaves ◽  
Sugar Levels ◽  
Stimulation Of

The photosynthetic response of grapevine leaves (Vitis vinifera L. cv. Riesling) to low temperature was studied to determine the role of end-product limitation and orthophosphate (Pi) recycling to the chloroplast under these conditions. As reported previously, the response of photosynthesis in air to stomatal conductance declined at temperatures below 15°C, suggesting that at low temperatures inhibition of photosynthesis in grapevine has a strong non-stomatal component. Stimulation of carbon assimilation at ambient CO2 by reducing O2 from 21 to 2 kPa, O2 declined to zero below 15°C, a phenomenon often associated with a restriction in photosynthesis due to end-product-synthesis limitation. This stimulation could be restored by feeding Pi. Photosynthesis in leaf disks at both high and low irradiances in non-photorespiratory conditions (1% CO2) was highly sensitive to reductions in temperature. Below 15°C, feeding Pi caused a large stimulation of photosynthetic O2 evolution. Metabolite measurements indicated that despite a decline in Rubisco carbamylation state, ribulose 1,5-bisphosphate (RuBP) levels dropped at low temperature and the ratio of 3-phosphoglycerate (3-PGA) to triose phosphate (TP) remained largely unchanged. These results suggest that grapevine-leaf photosynthesis is severely restricted at low temperature by non-stomatal mechanisms. The return of Pi to the chloroplast plays an important role in this limitation but a coordinated set of regulatory processes maintain a homeostasis of phosphorylated sugar levels.

Photosynthetic O2 evolution and apparent H+ uptake by slices of greening barley and maize leaves in aerobic and anaerobic solutions

1973 ◽  
Vol 51 (10) ◽  
pp. 1953-1957 ◽  
Author(s):  
Ulrich Lüttge
Keyword(s):  
Bundle Sheath ◽  
O2 Evolution ◽  
Strictly Anaerobic ◽  
Ph Change ◽  
Reaction Systems ◽  
Gas Streams ◽  
Maize Leaves ◽  
Photosynthetic O2 Evolution ◽  
Varied Composition ◽  
Aerobic And Anaerobic

Apparent rates of photosynthetic O2 evolution and light-dependent pH change (Δ[H+]) were measured in solutions containing leaf slices and bubbled with gas streams of varied composition. Intracellular recycling of O2 and CO2 between photosynthetic and respiratory reaction systems seems to be possible in green cells in the light. As a result of photosynthetic O2 evolution, the tissue and the solution are never strictly anaerobic even after prolonged bubbling with N2. Internal gas exchange is more pronounced in slices from the leaves of maize (a C-4 plant) having the complex Kranz tissue differentiation of mesophyll and bundle sheath, than in the leaves of barley (a C-3 plant).Light-dependent Δ[H+] is observed under all conditions used, i.e. in air, air – CO2, pure N2, and N2 + CO2. During the early stages of greening of etiolated leaves, Δ[H+] is found to be closely related to photosynthetic O2 evolution. After prolonged greening, Δ[H+] is larger in air – CO2 than in air. In pure N2, Δ[H+] is smaller and apparent O2 evolution is larger than in N2 + CO2. These results are discussed in relation to the hypothesis that part of light-dependent Δ[H+] is independent of concomitant photosynthetic CO2 fixation.

scholarly journals Does superoxide anion participate in 2-oxoglutarate-dependent hydroxylation?

1982 ◽  
Vol 205 (2) ◽  
pp. 339-344 ◽  
Author(s):  
Elisabeth Holme ◽  
Göran Lindstedt ◽  
Sven Lindstedt ◽  
Ingalill Nordin
Keyword(s):  
Superoxide Dismutase ◽  
Superoxide Anion ◽  
Potent Inhibitor ◽  
Enzymic Activity ◽  
Heat Inactivation ◽  
Low Molecular Weight ◽  
Enzyme Protein ◽  
Erythrocyte Superoxide Dismutase ◽  
Rule Out

The possible role of superoxide anion in 2-oxoglutarate-coupled dioxygenase reactions has been investigated. γ-Butyrobetaine hydroxylase (EC 1.14.11.1) was inhibited by human erythrocyte superoxide dismutase (EC 1.15.1.1), probably due to release of Cu2+ or Zn2+, as the inhibition was more pronounced after heat-inactivation of the dismutase and as Cu2+ was a potent inhibitor. Bovine superoxide dismutase and the Mn2+-containing superoxide dismutase from Escherichia coli were not inhibitory. Superoxide anion generated from xanthine/xanthine oxidase was not stimulatory and could not replace ascorbate. Thymine 7-hydroxylase (EC 1.14.11.6) and thymidine 2′-hydroxylase (EC 1.14.11.3) were not inhibited by erythrocyte superoxide dismutase or stimulated by superoxide anion. γ-Butyrobetaine hydroxylase was inhibited by a number of low-molecular-weight compounds, such as tetranitromethane, Nitro Blue Tetrazolium, adrenaline and Tiron, which may act as scavengers of superoxide anion. Involvement of this radical in other oxygenase reactions has been inferred from the findings that they were inhibitory for the respective enzymes. Several of these compounds also inhibited γ-butyrobetaine hydroxylase. It could be concluded from these experiments, however, that mechanisms other than disposal of superoxide anion might equally well be operative, such as hydrophobic interaction with the enzyme protein and interaction with compounds required for full enzymic activity, e.g. iron and ascorbate. The results appear to rule out a requirement for superoxide anion generated in free solution, and have not yielded evidence for participation of enzyme-bound superoxide anion in 2-oxoglutarate-dependent hydroxylations.

scholarly journals Mechanism for photosynthetic O2 evolution.

1986 ◽  
Vol 83 (13) ◽  
pp. 4586-4588 ◽  
Author(s):  
G. W. Brudvig ◽  
R. H. Crabtree
Keyword(s):  
O2 Evolution ◽  
Photosynthetic O2 Evolution
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