Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    C4 photosynthesis in a single C3 cell is theoretically inefficient but may ameliorate internal CO2 diffusion limitations of C3 leaves (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: Attempts are being made to introduce C4 photosynthetic characteristics into C3 crop plants by genetic manipulation. This research has focused on engineering single-celled C4-type CO2 concentrating mechanisms into C3 plants such as rice. Herein the pros and cons of such approaches are discussed with a focus on CO2 diffusion, utilizing a mathematical model of single-cell C4 photosynthesis. It is shown that a high bundle sheath resistance to CO2 diffusion is an essential feature of energy-efficient C4 photosynthesis. The large chloroplast surface area appressed to the intercellular airspace in C3 leaves generates low internal resistance to CO2 diffusion, thereby limiting the energy efficiency of a single-cell C4 concentrating mechanism, which relies on concentrating CO2 within chloroplasts of C3 leaves. Nevertheless the model demonstrates that the drop in CO2 partial pressure, pCO2, that exists between intercellular airspace and chloroplasts in C3 leaves at high photosynthetic rates, can be reversed under high irradiance when energy is not limiting. The model shows that this is particularly effective at lower intercellular pCO2. Such a system may therefore be of benefit in water-limited conditions when stomata are closed and low intercellular pCO2 increases photorespiration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.0016-8025.2003.01061.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Photosynthetic oxygen exchange in C4 grasses: the role of oxygen as electron acceptor (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: C4 grasses of the NAD-ME type (Astrebla lappacea, Eleusine coracana, Eragrostis superba, Leptochloa dubia, Panicum coloratum, Panicum decompositum) and the NADP-ME type (Bothriochloa bladhii, Cenchrus ciliaris, Dichanthium sericeum, Panicum antidotale, Paspalum notatum, Pennisetum alopecuroides, Sorghum bicolor) were used to investigate the role of O2 as an electron acceptor during C4 photosynthesis. Mass spectrometric measurements of gross O2 evolution and uptake were made concurrently with measurements of net CO2 uptake and chlorophyll fluorescence at different irradiances and leaf temperatures of 30 and 40 °C. In all C4 grasses gross O2 uptake increased with increasing irradiance at very high CO2 partial pressures (pCO2) and was on average 18% of gross O2 evolution. Gross O2 uptake at high irradiance and high pCO2 was on average 3.8 times greater than gross O2 uptake in the dark. Furthermore, gross O2 uptake in the light increased with O2 concentration at both high CO2 and the compensation point, whereas gross O2 uptake in the dark was insensitive to O2 concentration. This suggests that a significant amount of O2 uptake may be associated with the Mehler reaction, and that the Mehler reaction varies with irradiance and O2 concentration. O2 exchange characteristics at high pCO2 were similar for NAD-ME and NADP-ME species. NAD-ME species had significantly greater O2 uptake and evolution at the compensation point particularly at low irradiance compared to NADP-ME species, which could be related to different rates of photorespiratory O2 uptake. There was a good correlation between electron transport rates estimated from chlorophyll fluorescence and gross O2 evolution at high light and high pCO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2003.01112.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Carbonic anhydrase and C4 photosynthesis: a transgenic analysis (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: Carbonic anhydrase (CA, EC 4.2.1.1) catalyses the first reaction in the C4 photosynthetic pathway, the conversion of atmospheric CO2 to bicarbonate in the mesophyll cytosol. To examine the importance of the enzyme to the functioning of the C4 photosynthetic pathway, Flaveria bidentis (L.) Kuntze, a C4 dicot, was genetically transformed with an antisense construct in which the cDNA encoding a putative cytosolic CA (CA3) was placed under the control of a constitutive promoter. Some of the primary transformants had impaired CO2 assimilation rates and required high CO2 for growth. The T1 progeny of four primary transformants were used to examine the quantitative relationship between leaf CA activity and CO2 assimilation rate. CA activity was determined in leaf extracts with a mass spectrometric technique that measured the rate of 18O exchange from doubly labelled 13C18O2. Steady-state CO2 assimilation rates were unaffected by a decrease in CA activity until CA activity was less than 20% of wild type when they decreased steeply. Transformants with less than 10% of wild-type CA activity had very low CO2 assimilation rates and grew poorly at ambient CO2 partial pressure. Reduction in CA activity also increased the CO2 partial pressure required to saturate CO2 assimilation rates. The present data show that CA activity is essential for the functioning of the C4 photosynthetic pathway.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2003.01157.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The photosynthesis of young Panicum C4 leaves is not C3-like (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 21 (1998), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Evidence is presented contrary to the suggestion that C4 plants grow larger at elevated CO2 because the C4 pathway of young C4 leaves has C3-like characteristics, making their photosynthesis O2 sensitive and responsive to high CO2. We combined PAM fluorescence with gas exchange measurements to examine the O2 dependence of photosynthesis in young and mature leaves of Panicum antidotale (C4, NADP-ME) and P. coloratum (C4, NAD-ME), at an intercellular CO2 concentration of 5 Pa. P. laxum (C3) was used for comparison. The young C4 leaves had CO2 and light response curves typical of C4 photosynthesis. When the O2 concentration was gradually increased between 2 and 40%, CO2 assimilation rates (A) of both mature and young C4 leaves were little affected, while the ratio of the quantum yield of photosystem II to that of CO2 assimilation (ΦPSII/ΦCO2) increased more in young (up to 31%) than mature (up to 10%) C4 leaves. A of C3 leaves decreased by 1·3 and ΦPSII/ΦCO2 increased by 9-fold, over the same range of O2 concentrations. Larger increases in electron transport requirements in young, relative to mature, C4 leaves at low CO2 are indicative of greater O2 sensitivity of photorespiration. Photosynthesis modelling showed that young C4 leaves have lower bundle sheath CO2 concentration, brought about by higher bundle sheath conductance relative to the activity of the C4 and C3 cycles and/or lower ratio of activities of the C4 to C3 cycles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00348.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The growth response of C4 plants to rising atmospheric CO2 partial pressure: a reassessment (2000)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 23 (2000), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Despite mounting evidence showing that C4 plants can accumulate more biomass at elevated CO2 partial pressure (p(CO2)), the underlying mechanisms of this response are still largely unclear. In this paper, we review the current state of knowledge regarding the response of C4 plants to elevated p(CO2) and discuss the likely mechanisms. We identify two main routes through which elevated p(CO2) can stimulate the growth of both well-watered and water-stressed C4 plants. First, through enhanced leaf CO2 assimilation rates due to increased intercellular p(CO2). Second, through reduced stomatal conductance and subsequently leaf transpiration rates. Reduced transpiration rates can stimulate leaf CO2 assimilation and growth rates by conserving soil water, improving shoot water relations and increasing leaf temperature. We argue that bundle sheath leakiness, direct CO2 fixation in the bundle sheath or the presence of C3-like photosynthesis in young C4 leaves are unlikely explanations for the high CO2-responsiveness of C4 photosynthesis. The interactions between elevated p(CO2), leaf temperature and shoot water relations on the growth and photosynthesis of C4 plants are identified as key areas needing urgent research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2000.00609.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Carbon isotope discrimination in C3-C4 intermediates (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Carbon isotope discrimination in C3–C4 intermediates is determined by fractionations during diffusion and the biochemical fractionations occurring during CO2 fixation. These biochemical fractionations in turn depend on the fractionation by Rubisco in the mesophyll, the amount of CO2 fixation. These biochemical fractionations in turn depend on the fractionation by Rubisco in the mesophyll, the amount of CO2 fixation occurring in the bundle sheath, the extent of bundle-sheath leakiness and the contribution which C4-cycle activity makes to the CO2 pool there. In most instances, carbon isotope discrimination in C3–C4 intermediates is C3-like because only a small fraction of the total carbon fixed is fixed in the bundle sheath. In particular, this must be the case for Flaveria intermediates which initially fix substantial amounts of CO2 into C4-acids. In C3–C4 intermediates that refix photorespiratory CO2 alone, it is possible for carbon isotope discrimination to be greater than in C3-species, particularly at low CO2 pressures or at high leaf temperatures. Short-term measurements of carbon isotope discrimination and gas exchange of leaves can be used to study the photosynthetic pathways of C3-C4 intermediates and their hybrids as has recently been done for C3 and C4 species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb01656.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Some relationships between the biochemistry of photosynthesis and the gas exchange of leaves (1981)
    Springer
    Planta 153 (1981), S. 376-387 
    Details
    ISSN: 1432-2048
    Keywords: CO2 assimilation ; Electron transport ; Gas exchange ; Phaseolus ; Photosynthesis (C3) ; Ribulose bisphosphate carboxylase-oxygenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A series of experiments is presented investigating short term and long term changes of the nature of the response of rate of CO2 assimilation to intercellular p(CO2). The relationships between CO2 assimilation rate and biochemical components of leaf photosynthesis, such as ribulose-bisphosphate (RuP2) carboxylase-oxygenase activity and electron transport capacity are examined and related to current theory of CO2 assimilation in leaves of C3 species. It was found that the response of the rate of CO2 assimilation to irradiance, partial pressure of O2, p(O2), and temperature was different at low and high intercellular p(CO2), suggesting that CO2 assimilation rate is governed by different processes at low and high intercellular p(CO2). In longer term changes in CO2 assimilation rate, induced by different growth conditions, the initial slope of the response of CO2 assimilation rate to intercellular p(CO2) could be correlated to in vitro measurements of RuP2 carboxylase activity. Also, CO2 assimilation rate at high p(CO2) could be correlated to in vitro measurements of electron transport rate. These results are consistent with the hypothesis that CO2 assimilation rate is limited by the RuP2 saturated rate of the RuP2 carboxylase-oxygenase at low intercellular p(CO2) and by the rate allowed by RuP2 regeneration capacity at high intercellular p(CO2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384257
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Effect of salinity and humidity on δ13C value of halophytes—Evidence for diffusional isotope fractionation determined by the ratio of intercellular/atmospheric partial pressure of CO2 under different environmental conditions (1982)
    Springer
    Oecologia 52 (1982), S. 121-124 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seedlings of two mangrove species, Avicennia marina and Aegiceras corniculatum, were grown in a range of salinities and humidities in controlled environment chambers, and Phaseolus vulgaris plants were grown in the glasshouse. The fractionation of carbon isotopes in the three species was correlated with the ratio of intercellular and ambient partial pressures of CO2. The results are consistent with fractionation being due both to diffusion in air and to carboxylation in the leaf. It was concluded that the latter process discriminates against 13CO2 relative to 12CO2 by about 27‰.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349020
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Effects of partial defoliation, changes of irradiance during growth, short-term water stress and growth at enhanced p(CO2) on the photosynthetic capacity of leaves of Phaseolus vulgaris L. (1984)
    Springer
    Planta 160 (1984), S. 320-329 
    Details
    ISSN: 1432-2048
    Keywords: Carbon dioxide (high partial pressure) ; Electron transport ; Gas exchange ; Phaseolus (CO2 assimilation) ; Photosynthesis at high p(CO2) ; Ribulose-1,5-bisphosphate carboxylase-oxygenase ; Defoliation ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of CO2-assimilation rate to the intercellular partial pressure of CO2 (p(CO2)) is used to analyse the effects of various growth treatments on the photosynthetic characteristics of P. vulgaris. Partial defoliation caused an increase in CO2-assimilation rate at all intercellular p(CO2). A change in the light regime for growth from high to low light levels caused a decrease of CO2-assimilation rate at all intercellular p(CO2). Growth in a CO2-enriched atmosphere resulted in lowered assimilation assimilation rates compared with controls at comparable intercellular p(CO2). Short-term water stress initially caused only a decline in the CO2-assimilation rate at high intercellular p(CO2), but not at low intercellular p(CO2). Except under severe water stress, changes in the initial slope of the response of CO2-assimilation rate to intercellular p(CO2) were in parallel to those of the in-vitro activity of ribulose-1,5-bisphosphate (RuBP) carboxylase. From the results, we infer that partial defoliation, changes in the light regime for growth, and growth in a CO2-enriched atmosphere cause parallel changes in RuBP-carboxylase (EC 4.1.1.39) activity and the “capacity for RuBP regeneration”, whereas short-term water stress initially causes only a decline in the RuBP-regeneration capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393413
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A biochemical model of photosynthetic CO2 assimilation in leaves of C3 species (1980)
    Springer
    Planta 149 (1980), S. 78-90 
    Details
    ISSN: 1432-2048
    Keywords: Electron transport ; Leaf model ; Light and CO2 assimilation ; Ribulose bisphosphate carboxylase-oxygenase ; Temperature ; Photosynthesis (C3)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various aspects of the biochemistry of photosynthetic carbon assimilation in C3 plants are integrated into a form compatible with studies of gas exchange in leaves. These aspects include the kinetic properties of ribulose bisphosphate carboxylase-oxygenase; the requirements of the photosynthetic carbon reduction and photorespiratory carbon oxidation cycles for reduced pyridine nucleotides; the dependence of electron transport on photon flux and the presence of a temperature dependent upper limit to electron transport. The measurements of gas exchange with which the model outputs may be compared include those of the temperature and partial pressure of CO2(p(CO2)) dependencies of quantum yield, the variation of compensation point with temperature and partial pressure of O2(p(O2)), the dependence of net CO2 assimilation rate on p(CO2) and irradiance, and the influence of p(CO2) and irradiance on the temperature dependence of assimilation rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386231
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...