Rate Limitation of Non-Steady-State Photosynthesis by Ribulose-1,5-Bisphosphate Carboxylase in Spinach

1989 ◽  
Vol 16 (6) ◽  
pp. 487 ◽  
Author(s):  
IE Woodrow ◽  
KA Mott
Keyword(s):  
Relaxation Time ◽  
Steady State ◽  
Spinacia Oleracea ◽  
Exponential Phase ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Mathematical Framework ◽  
Bisphosphate Carboxylase ◽  
Quantitative Expression ◽  
Spinacia Oleracea L

A mathematical framework was developed to analyse rate limitation of non-steady-state photosynthesis following an increase in photon flux density (PFD). This analysis was employed to resolve an exponential phase of the photosynthetic response of Spinacia oleracea L. to a step increase from darkness to moderate PFD. This phase had a relaxation time of approximately 5 min, similar to the relaxation time for the activation of ribulose-1,5-bisphosphate carboxylase (Rubisco) as determined by freeze-clamp experiments following the same change in PFD. Furthermore, as the time in darkness prior to illumination was increased, the exponential phase contributed more to the overall trajectory of photosynthesis following the increase in light. The relaxation time for the increase in the contribution of this phase was 24 min. Freeze-clamp studies showed a relaxation time of 28 min for Rubisco deactivation in the dark. These results, together with measurements of RuP2 levels, suggest that the exponential phase resolved from gas exchange experiments was limited by activation of Rubisco and that Rubisco deactivation in the dark was the reason that this phase contributed more to the overall photosynthetic trajectory as time in darkness increased. A quantitative expression for the amount of extra photosynthesis that could have been obtained had Rubisco activated instantly following an increase in PFD was derived and discussed in relation to optimal functioning of the system under different environmental conditions.

Activities of the cyanide-resistant respiratory pathway in leaves of sun and shade species

2001 ◽  
Vol 28 (1) ◽  
pp. 27 ◽  
Author(s):  
Ko Noguchi ◽  
Chun-Sim Go ◽  
Ichiro Terashima ◽  
Shingo Ueda ◽  
Tadashi Yoshinari
Keyword(s):  
Spinacia Oleracea ◽  
Proton Translocation ◽  
Plant Mitochondria ◽  
Oxygen Electrode ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Respiratory Pathway ◽  
Higher Plant ◽  
Atp Production ◽  
Spinacia Oleracea L

Higher plant mitochondria have a cyanide-resistant alternative respiratory pathway of electron transport (AP) that is not coupled to proton translocation. To characterise the ecophysiology of this apparently ‘wasteful’ pathway, we constructed a system consisting of a gas-phase oxygen electrode and an air sampling line for measurement of stable oxygen isotope ratios. With this system, we were able to measure respiratory rates of a small amount of leaf segments of ca 0.6 g fresh weight, and collect about 100 L of the air from the oxygen electrode chamber several times. The 18 O/16 O ratio in the air samples was measured by mass spectrometry. The activity of AP was estimated based on the isotopic discrimination of 18 O. We used the leaves of Alocasia odora (Lodd.) Spach., a shade species, and Spinacia oleracea L. and Phaseolus vulgaris L., sun species. These plants were grown at two levels of photosynthetically active photon flux density (PPFD). Three main findings were: (1) in the leaves of A. odora, the contribution of AP was less than 10% of the total respiratory rate, irrespective of growth PPFD; (2) for the sun species grown at high PPFD, the contribution of AP in the leaves was about 40% early in the night, but decreased dramatically late in the night; and (3) when S. oleracea was grown at low PPFD, the contribution of AP in the leaves declined. The low activity of AP in the leaves of A. odora suggests that the efficiency of adenosine triphosphate (ATP) production (ATP/O 2 ) of this species is high. This may be especially important in shaded environments where input of light energy is low. We also suggest that, in the leaves of sun species, ATP/O 2 changes depending on the conditions.

Limitation of the Rate of Ribulosebisphosphate Carboxylase Activation by Carbamylation and Ribulosebisphosphate Carboxylase Activase Activity: Development and Tests of a Mechanistic Model

1996 ◽  
Vol 23 (2) ◽  
pp. 141 ◽  
Author(s):  
IE Woodrow ◽  
ME Kelly ◽  
KA Mott
Keyword(s):  
Mechanistic Model ◽  
Large Subunit ◽  
Intercellular Co2 Concentration ◽  
Rubisco Activase ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Bisphosphate Carboxylase ◽  
Ribulosebisphosphate Carboxylase ◽  
Kinetics Of ◽  
Rubisco Activation

A mechanistically-based model of light-mediated activation of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is developed. The model describes the kinetics of Rubisco activation following a relatively rapid increase in photon flux density (PPFD) from an initially low level. Underlying the model is the assumption that there are two slow processes that could potentially limit the rate of light-mediated Rubisco activation. These processes are the addition of the activator CO2 to the large subunit of Rubisco, which is accompanied by a conformational change in the enzyme (carbamylation), and activase-mediated removal of ribulose 1,5-bisphosphate from the inactive form of the enzyme. The contribution of these slow processes to the overall activation kinetics of Rubisco was resolved by measuring Rubisco activation in whole spinach leaves using non-steady-state CO2 exchange. It was found that when the change in PPFD was relatively small and a correspondingly small proportion of the Rubisco pool was activated, the kinetics of activation were highly sensitive to the intercellular CO2 concentration (ci). The apparent rate constant for activation under these conditions was found to be similar to that for the carbamylation of purified spinach Rubisco. When the change in PPFD and the proportion of Rubisco activated was relatively large, however, the kinetics of Rubisco activation were almost completely CO2 insensitive and were consistent with those of an enzyme-catalysed reaction. It is suggested that (1) CO2-insensitive activation reflects the operation of Rubisco activase and (2) the increasing CO2 sensitivity seen as the change in PPFD decreases reflects a transition to limitation by carbamylation.

Phosphate Requirement, Photosynthesis, and Diel Cell Cycle of Scenedesmus obliquas Under Fluctuating Light

1987 ◽  
Vol 44 (10) ◽  
pp. 1753-1758 ◽  
Author(s):  
C. N. Shin ◽  
G-Y Rhee ◽  
J. Chen
Keyword(s):  
Steady State ◽  
Average Rate ◽  
Scenedesmus Obliquus ◽  
Constant Light ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Cell Numbers ◽  
P Limitation ◽  
Fluctuating Light ◽  
Light Fluctuation

The effect of light fluctuation (0.06 Hz) on P requirement, photosynthesis, and the diel cell-division cycle was investigated in Scenedesmus obliquus in a chemostat under a 12 h day: 12 h night cycle. P requirement was much less under oscillating than under constant daylight of the same photon flux density. However, cell chlorophyll a was significantly higher, indicating an increased N requirement. There was little difference in photosynthetic efficiency (the slope of the photosynthesis–light regression) between oscillating and constant light, but photosynthetic capacity was higher in fluctuating light. Cell C was also higher. A strong diel rhythmicity in steady-state cell numbers was observed with little phase difference between oscillating and constant light. Although steady-state cell numbers under P limitation were significantly higher under fluctuating light, there was no difference in instantaneous growth rates and their diel distribution. At a dilution rate of 0.6∙d−1, cell death occurred at an average rate of −0.56∙d−1 between 4 h before and 5 h after the onset of the dark period.

scholarly journals Bolting and Growth of Spinacia oleracea L. Can be Altered by Modifying the Photoperiod during Transplant Production

HortScience ◽  
2000 ◽  
Vol 35 (4) ◽  
pp. 624-626 ◽  
Author(s):  
Changhoo Chun ◽  
Ayumi Watanabe ◽  
Toyoki Kozai ◽  
Hyeon-Hye Kim ◽  
Junya Fuse
Keyword(s):  
High Temperature ◽  
Spinacia Oleracea ◽  
Market Value ◽  
Photon Flux ◽  
Artificial Light ◽  
Photosynthetic Photon Flux ◽  
Flower Stalk ◽  
Spinacia Oleracea L ◽  
Critical Photoperiod ◽  
Long Photoperiod

Spinach (Spinacia oleracea L. cv. Dimple) was chosen to determine whether bolting (i.e., elongation of flower stalks) could be controlled by manipulating the photoperiod during transplant production in a closed system using artificial light. Plants grown under various photoperiods during transplant production were transferred and cultured under natural short photoperiods and artificial long photoperiods. Vegetative growth at transplanting tended to be greater with the longer photoperiod because of the increased integrated photosynthetic photon flux. Bolting initiation reacted qualitatively to a long photoperiod, and the critical photoperiod for bolting initiation was longer than 13 h and shorter than 15 h. The plants grown under a longer photoperiod during transplant production had longer flower stalks at harvest. The long photoperiod and/or high temperature after transplanting therefore promoted flower stalk elongation. Growing plants under a photoperiod that was shorter than the critical photoperiod during transplant production reduced elongation of the flower stalks, thus there was no loss of market value even though the plants were cultured under a long photoperiod and high temperature for 2 weeks after transplanting.

scholarly journals Incorporation of carbon from photosynthetic products into 2-carboxyarabinitol-1-phosphate and 2-carboxyarabinitol

1994 ◽  
Vol 304 (3) ◽  
pp. 781-786 ◽  
Author(s):  
P J Andralojc ◽  
G W Dawson ◽  
M A J Parry ◽  
A J Keys
Keyword(s):  
Specific Binding ◽  
Anion Exchange Chromatography ◽  
Photosynthetic Photon Flux Density ◽  
French Bean ◽  
Exchange Chromatography ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Bisphosphate Carboxylase ◽  
Naturally Occurring ◽  
Subsequent Exposure

The synthesis of 2-carboxy-D-arabinitol-1-phosphate (CA1P), the naturally occurring inhibitor of ribulose-1,5-bisphosphate carboxylase/oxygenase, was studied in leaves of the French bean Phaseolus vulgaris, L. Leaves were supplied with air containing 14CO2 in the light then the plants were transferred to normal air in the light or in the dark. Leaf samples were frozen in liquid nitrogen, ground to a powder and extracted with acid. Lipids, pigments and cations were removed from the extract and CA1P and 2-carboxy-D-arabinitol (CA) recovered by anion exchange chromatography. The CA1P was further purified by its specific binding to purified ribulose-1,5-bisphosphate carboxylase/oxygenase. CA and CA1P were identified by chromatographic properties and n.m.r. spectra. When plants were kept for 15 h in darkness after exposure to 14CO2, up to 2.2% and 5.5% of the radioactivity in the extracts was present in CA1P and CA, respectively. The most radioactivity appeared in these compounds when photosynthesis from 14CO2 took place at low photosynthetic photon flux density (PPFD). Under such conditions, radioactivity was detected in CA1P after only 10 min. During subsequent exposure to normal air (12CO2) at low PPFD the amount of radioactivity in CA1P remained almost constant for 6 h; in darkness the rate of incorporation of radioactivity into CA1P reached a maximum after 2 h and the radioactivity was still increasing 6 h later. At low PPFD, the amount of CA1P in the leaves reached a maximum after 2 h. In darkness, the amount of CA1P began to increase rapidly after a lag of almost 1 h, well ahead of the increase in radioactivity in CA1P.

Variations in photosynthetic, anatomical, and enzymatic leaf traits and correlations with growth in recently selected Populus hybrids

1987 ◽  
Vol 17 (4) ◽  
pp. 273-283 ◽  
Author(s):  
R. Ceulemans ◽  
I. Impens ◽  
V. Steenackers
Keyword(s):  
Growth Performance ◽  
Principal Component ◽  
Net Photosynthesis ◽  
Leaf Traits ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Ribulose Bisphosphate Carboxylase ◽  
Bisphosphate Carboxylase ◽  
Shoot Height

Several photosynthetic, anatomical, and enzymatic leaf traits were studied on 1- and 2-year-old fast growing Populus clones representing interspecific hybrids of P. deltoides, P. trichocarpa, and P. maximowiczii. Growth performance of the clones was studied with container-grown plants and for 5 years in the field. Considerable variation in photosynthetic, anatomical, and enzymatic leaf traits was found, but variation in growth differences among the clonal groups was minimal. Photosynthetic photon flux density saturated net photosynthesis of 1-year-old container-grown plants was significantly correlated with shoot height growth, but none of the other leaf traits measured showed a significant correlation with any of the growth characteristics. Clonal groups could be segregated by taxonomic and genetic affinities with hierarchical clustering and principal component analysis. Although enzymatic and biochemical traits (area leaf weight, ribulose-bisphosphate carboxylase and phosphoenolpyruvate carboxylase activities, protein content) and adaxial stomatal frequency can be used to discriminate among clonal groups, no significant regression of these leaf traits on growth performance was observed.

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