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  • Electronic Resource  (19)
  • 1
    Electronic Resource
    Electronic Resource
    Stomatal Conductance and Photosynthesis (1982)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology 33 (1982), S. 317-345 
    Details
    ISSN: 0066-4294
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pp.33.060182.001533
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  • 2
    Electronic Resource
    Electronic Resource
    Thylakoid membrane responses to moderately high leaf temperature in Pima cotton (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 27 (2004), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Photosynthesis is inhibited by high temperatures that plants are likely to experience under natural conditions. Both  increased  thylakoid  membrane  ionic  conductance and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) deactivation have been suggested as the primary cause. The moderately heat-tolerant crop Pima S-6 cotton (Gossypium barbadense) was used to examine heat stress-induced inhibition of photosynthesis. Previous field-work indicated that moderate heat stress (T = 35–45 °C) is associated with very rapid leaf temperature changes. Therefore, a system was devised for rapidly heating intact, attached leaves to mimic natural field heat-stress conditions and monitored Rubisco activation, carbon-cycle metabolites, thylakoid ionic conductance, and photosystem I activity. As a proxy for NADPH and stromal redox status the activation state of NADP-malate dehydrogenase (NADP-MDH) was measured. In dark-adapted cotton leaves, heating caused an increase in thylakoid permeability at temperatures as low as 36 °C. The increased permeability did not cause a decline in adenosine 5′-triphosphate (ATP) levels during steady-state or transient heating. Rapid heating caused a transient decline in ribulose 1,5-bisphosphate without a decrease in Rubisco activation. Sustained heating caused a decline in Rubisco activation and also oxidized the stroma as judged by NADP-MDH activation and this is hypothesized to result from increased cyclic photophosphorylation, explaining the maintenance of ATP content in the face of increased thylakoid membrane ion leakiness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01172.x
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  • 3
    Electronic Resource
    Electronic Resource
    Electron transport is the functional limitation of photosynthesis in field-grown Pima cotton plants at high temperature (2004)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 27 (2004), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Restrictions to photosynthesis can limit plant growth at high temperature in a variety of ways. In addition to increasing photorespiration, moderately high temperatures (35–42 °C) can cause direct injury to the photosynthetic apparatus. Both carbon metabolism and thylakoid reactions have been suggested as the primary site of injury at these temperatures. In the present study this issue was addressed by first characterizing leaf temperature dynamics in Pima cotton (Gossypium barbadense) grown under irrigation in the US desert south-west. It was found that cotton leaves repeatedly reached temperatures above 40 °C and could fluctuate as much as 8 or 10 °C in a matter of seconds. Laboratory studies revealed a maximum photosynthetic rate at 30–33 °C that declined by 22% at 45 °C. The majority of the inhibition persisted upon return to 30 °C. The mechanism of this limitation was assessed by measuring the response of photosynthesis to CO2 in the laboratory. The first time a cotton leaf (grown at 30 °C) was exposed to 45 °C, photosynthetic electron transport was stimulated (at high CO2) because of an increased flux through the photorespiratory pathway. However, upon cooling back to 30 °C, photosynthetic electron transport was inhibited and fell substantially below the level measured before the heat treatment. In the field, the response of assimilation (A) to various internal levels of CO2 (Ci) revealed that photosynthesis was limited by ribulose-1,5-bisphosphate (RuBP) regeneration at normal levels of CO2 (presumably because of limitations in thylakoid reactions needed to support RuBP regeneration). There was no evidence of a ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) limitation at air levels of CO2 and at no point on any of 30 A–Ci curves measured on leaves at temperatures from 28 to 39 °C was RuBP regeneration capacity measured to be in substantial excess of the capacity of Rubisco to use RuBP. It is therefore concluded that photosynthesis in field-grown Pima cotton leaves is functionally limited by photosynthetic electron transport and RuBP regeneration capacity, not Rubisco activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2004.01171.x
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  • 4
    Electronic Resource
    Electronic Resource
    The response of isoprene emission rate and photosynthetic rate to photon flux and nitrogen supply in aspen and white oak trees (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Isoprene is the primary biogenic hydrocarbon emitted from temperate deciduous forest ecosystems. The effects of varying photon flux density (PFD) and nitrogen growth regimes on rates of isoprene emission and net photosynthesis in potted aspen and white oak trees are reported. In both aspen and oak trees, whether rates were expressed on a leaf area or dry mass basis, (1) growth at higher PFD resulted in significantly higher rates of isoprene emission, than growth at lower PFD, (2) there is a significant positive relationship between isoprene emission rate and leaf nitrogen concentration in both sun and shade trees, and (3) there is a significant positive correlation between isoprene emission rate and photosynthetic rate in both sun and shade trees. The greater capacity for isoprene emission in sun leaves was due to both higher leaf mass per unit area and differences in the biochemical and/or physiological properties that influence isoprene emission. Positive correlations between isoprene emission rate and leaf nitrogen concentration support the existence of mechanisms that link leaf nitrogen status to isoprene synthase activity. Positive correlations between isoprene emission rate and photosynthesis rate support previous hypotheses that isoprene emission plays a role in protecting photosynthetic mechanisms during stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00388.x
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  • 5
    Electronic Resource
    Electronic Resource
    Responses to elevated CO2 of Flaveria linearis plants having a reduced activity of cytosolic fructose-1,6-bisphosphatase (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Wide variation exists in the growth responses of C3 plants to elevated CO2 levels. To investigate the role of photosynthetic feedback in this phenomenon, photosynthetic parameters and growth were measured for lines of Flaveria linearis with low, intermediate or high cytosolic fructose-1,6-bisphosphatase (cytFBPase) activity when grown at either 35 or 65 Pa CO2. The effects of pot size on the responses of these lines to elevated CO2 were also examined. Photosynthesis and growth of plants with low cytFBPase activity were less responsive to elevated CO2, and these plants had a reduced maximum potential for photosynthesis and growth. Plants with intermediate cytFBPase activity also showed a lower relative growth enhancement when grown at 65 Pa CO2. There was a significant pot size effect on photosynthesis and growth for line 85-1 (high cytFBPase). This effect was greatest for line 85-1 when grown at 35 Pa CO2, since these plants showed the greatest downward acclimation of photosynthesis when grown in small pots. There was a minimal pot size effect for line 84-9 (low cytFBPase), and this could be partly attributed to the reduced CO2 sensitivity of this line. It is proposed that the capacity for sucrose synthesis in C3, plants is partly responsible for their wide variation in CO2 responsiveness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00221.x
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  • 6
    Electronic Resource
    Electronic Resource
    Genetic and physiological characterization of Flaveria linearis plants having a reduced activity of cytosolic fructose-1.6-bisphosphatase (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We investigated the genetic control of cytosolic fructose-1,6-bisphosphatase (cytFBPase) activity, and the relationships between sucrose synthesis capacity and photosynthesis, growth, flowering and whole-plant carbon partitioning in Flaveria linearis Lag. F1; F2, and selfed lines generated from plants with low or high cytFBPase activity were used. CytFBPase activity was controlled by one gene and inherited co-dominantly, giving three classes of activity (low, intermediate and high). Reversed O2 sensitivity of photosynthesis, which indicates an end-product limitation on photosynthesis, was controlled by one gene and co-segregated with low cytFBPase activity. A low activity of cytFBPase decreased the growth rate. A recessive day-neutral flowering trait in Flaveria linearis did not co-segregate with cytFBPase activity. Plants with low cytFBPase activity had an increased shoot-to-root ratio, and flowering caused an additional shift in carbon partitioning to shoots only in plants with low cytFBPase activity. These data indicate that altering sucrose synthesis can affect photosynthesis and plant growth and development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1996.tb00220.x
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  • 7
    Electronic Resource
    Electronic Resource
    Rapid appearance of 13C in biogenic isoprene when 13CO2 is fed to intact leaves (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 16 (1993), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Biogenic isoprene substantially affects atmospheric chemistry, but it is not known how or why many plants, especially trees, make isoprene. We fed 13CO2 to leaves of Quercus rubra and monitored the incorporation of 13C into isoprene by mass spectrometry. After feeding 13CO2 for 9 min we found all possible labelling patterns from completely unlabelled to fully labelled isoprene. By 18 min, 84% of the carbon atoms in isoprene were 13C. Labelling of the last 20% of the carbon atoms was much slower than labelling of the first 80%. The rate of labelling of isoprene was similar to that reported for phosphoglyceric acid indicating that there is a close linkage between the carbon source for isoprene synthesis and the photosynthetic carbon reduction pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1993.tb00907.x
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  • 8
    Electronic Resource
    Electronic Resource
    Biochemical regulation of isoprene emission (2003)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 26 (2003), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Isoprene (C5H8) is emitted from many plants and has a substantial effect on atmospheric chemistry. There are several models to estimate the rate of isoprene emission used to calculate the impact of isoprene on atmospheric processes. The rate of isoprene synthesis will depend either on the activity of isoprene synthase or the availability of its substrate dimethylallyl pyrophosphate (DMAPP). To investigate long-term regulation of isoprene synthesis, the isoprene emission rate of 15 kudzu leaves was measured. The chloroplast DMAPP level of the five leaves with the highest emission rates and the five leaves with the lowest rates were determined by non-aqueous fractionation of the bulked leaf samples. Leaves with high basal emission rates had low levels of DMAPP whereas leaves with low basal emission rates had high DMAPP levels in their chloroplasts indicating that the activity of isoprene synthase exerts primary control over the basal emission rate. To investigate short-term regulation, isoprene precursors were fed to leaves. Feeding dideuterated deoxyxylulose (DOX-d2) to Eucalyptus leaves resulted in the emission of dideuterated isoprene. Results from DOX-d2 feeding experiments indicated that control of isoprene emission rate was shared between reactions upstream and downstream of the DOX entry into isoprene metabolism. In CO2-free air DOX always increased isoprene emission indicating that carbon availability was an important control factor. In N2, isoprene emission stopped and could not be recovered by adding DOX-d2. Taken together, these results indicate that the regulation of isoprene emission is shared among several steps and the relative importance of the different steps in controlling isoprene emission varies with conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0016-8025.2003.01059.x
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  • 9
    Electronic Resource
    Electronic Resource
    Intramolecular deuterium distributions reveal disequilibrium of chloroplast phosphoglucose isomerase (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 
D, deuterium
δD(NMR), chemical shift axis in a deuterium NMR spectrum
F6P, fructose-6-phosphate
G6P, glucose-6-phosphate
IRMS, isotope ratio mass spectrometry
NMR, nuclear magnetic resonance
PGI, phosphoglucose isomerase

Intramolecular deuterium distributions of the carbon-bound hydrogens of glucose were measured using deuterium nuclear magnetic resonance. Glucose isolated from leaf starch of common bean (Phaseolus vulgaris cv. Linden) or spinach (Spinacia oleracea cv. Giant nobel) was depleted in deuterium in the C(2) position, compared with glucose isolated from leaf sucrose or bean endosperm starch. In beans, the depletion of C(2) was independent of the light intensity during growth (150 or 700 μmol photons s–1 m–2). The ratio of glucose-6-phosphate to fructose-6-phosphate ([G6P]/[F6P]) in bean chloroplasts was 0·9 in high light, indicating that the phosphoglucose isomerase reaction was not in equilibrium ([G6P]/[F6P]) ≈ 3). This implies that the kinetic isotope effect of phosphoglucose isomerase depleted deuterium in the C(2) position of G6P. Because the depletion was the same, the chloroplastic ([G6P]/[F6P]) ratio was in disequilibrium irrespective of the light intensity. If the ([G6P]/[F6P]) ratio was in equilibrium, a large chloroplastic pool of G6P would be unavailable for regeneration of ribulose-1,5-bisphospate. We argue that chloroplast phosphoglucose isomerase activity is regulated to avoid this. The deuterium depletion of C(2) explains the known low overall deuterium abundance of leaf starch. This example shows that measurements of intramolecular deuterium distributions can be essential to understand overall deuterium abundances of plant material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00440.x
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  • 10
    Electronic Resource
    Electronic Resource
    High carbon dioxide and sun/shade effects on isoprene emission from oak and aspen tree leaves (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 14 (1991), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Isoprene (2-methyl 1, 3-butadiene) is emitted from many plants, especially trees. We tested the effect of growth at high CO2 partial pressure and sun versus shade conditions on the capacity of Quercus rubra L. (red oak) and Populus tremuloides Michx. (quaking aspen) leaves to make isoprene. Oak leaves grown at high CO2 partial pressure (65 Pa) had twice the rate of isoprene emission as leaves grown at 40Pa CO2. However, aspen leaves behaved oppositely, with high CO2-grown leaves having just 60-70% the rate of isoprene emission as leaves grown in 40 Pa CO2. Similar responses were observed from 25 to 35 °C leaf temperature during assay. The stimulation of isoprene emission by growth at high CO2 and the stimulation in high temperature resulted in isoprene emission consuming over 15% of the carbon fixed during photosynthesis in high-CO2 grown oak leaves assayed at 35 °C. Leaves from the south (sunny) sides of trees growing in natural conditions had rates of isoprene emission double those of leaves growing in shaded locations on the same trees. This effect was similar in both aspen and oak. The leaves used for these experiments had significantly different chlorophyll a/b ratios indicating they were functionally sun (from the sunny locations) or shade leaves (from the protected locations). Because the metabolic pathway of isoprene synthesis is unknown, we are unable to speculate about how or why these effects occur. However, these effects are more consistent with metabolic control of isoprene release rather than a metabolic leak of isoprene from metabolism. The results are also important for large scale modelling of isoprene emission and for predicting the effect of future increases in atmospheric CO2 level on isoprene emission from vegetation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1991.tb01509.x
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