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  • Artikel: DFG Deutsche Nationallizenzen  (13)
  • C4 photosynthesis  (8)
  • Crassulacean acid metabolism  (3)
  • C3  (2)
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  • Artikel: DFG Deutsche Nationallizenzen  (13)
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  • 1
    Digitale Medien
    Digitale Medien
    Photosynthetic acclimation of maize to growth under elevated levels of carbon dioxide (1999)
    Springer
    Planta 210 (1999), S. 115-125 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Key words: CO2 enrichment ; C4 photosynthesis ; Respiration ; Zea (CO2 enrichment)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract. The effects of elevated CO2 concentrations on the photochemistry, biochemistry and physiology of C4 photosynthesis were studied in maize (Zea mays L.). Plants were grown at ambient (350 μL L−1) or ca. 3 times ambient (1100 μL L−1) CO2 levels under high light conditions in a greenhouse for 30 d. Relative to plants grown at ambient CO2 levels, plants grown under elevated CO2 accumulated ca. 20% more biomass and 23% more leaf area. When measured at the CO2 concentration of growth, mature leaves of high-CO2-grown plants had higher light-saturated rates of photosynthesis (ca. 15%), lower stomatal conductance (71%), higher water-use efficiency (225%) and higher dark respiration rates (100%). High-CO2-grown plants had lower carboxylation efficiencies (23%), measured under limiting CO2, and lower leaf protein contents (22%). Activities of a number of C3 and C4 cycle enzymes decreased on a leaf-area basis in the high-CO2-grown plants by 5–30%, with NADP-malate dehydrogenase exhibiting the greatest decrease. In contrast, activities of fructose 1,6-bisphosphatase and ADP-glucose pyrophosphorylase increased significantly under elevated CO2 condition (8% and 36%, respectively). These data show that the C4 plant maize may benefit from elevated CO2 through acclimation in the capacities of certain photosynthetic enzymes. The increased capacity to synthesize sucrose and starch, and to utilize these end-products of photosynthesis to produce extra energy by respiration, may contribute to the enhanced growth of maize under elevated CO2.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004250050660
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  • 2
    Digitale Medien
    Digitale Medien
    Activity and quantity of ribulose bisphosphate carboxylase-and phosphoenolpyruvate carboxylase-protein in two Crassulacean acid metabolism plants in relation to leaf age, nitrogen nutrition, and point in time during a day/night cycle (1982)
    Springer
    Planta 154 (1982), S. 309-317 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Crassulacean acid metabolism ; Day/night cycle ; Kalanchoe ; Leaf age and CAM ; Mesembryanthemum ; Nitrogen nutrition ; Phosphoenolpyruvate carboxylase ; Ribulose bisphosphate carboxylase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Activity of ribulose 1,5-bisphosphate (RuBP) carboxylase in leaf extracts of the constitutive Crassulacean acid metabolism (CAM) plant Kalanchoe pinnata (Lam.) Pers. decreased with increasing leaf age, whereas the activity of phosphoenolpyruvate (PEP) carboxylase increased. Changes in enzyme activities were associated with changes in the amount of enzyme proteins as determined by immunochemical analysis, sucrose density gradient centrifugation, and SDS gel electrophoresis of leaf extracts. Young developing leaves of plants which received high amounts of NO 3 - during growth contained about 30% of the total soluble protein in the form of RuBP carboxylase; this value declined to about 17% in mature leaves. The level of PEP carboxylase in young leaves of plants at high NO 3 - was an estimated 1% of the total soluble protein and increased to approximately 10% in mature leaves, which showed maximum capacity for dark CO2 fixation. The growth of plants at low levels of NO 3 - decreased the content of soluble protein per unit leaf area as well as the extractable activity and the percentage contribution of both RUBP carboxylase and PEP carboxylase to total soluble leaf protein. There was no definite change in the ratio of RuBP carboxylase to PEP carboxylase activity with a varying supply of NO 3 - during growth. It has been suggested (e.g., Planta 144, 143–151, 1978) that a rhythmic pattern of synthesis and degradation of PEP carboxylase protein is involved in the regulation of β-carboxylation during a day/night cycle in CAM. No such changes in the quantity of PEP carboxylase protein were observed in the leaves of Kalanchoe pinnata (Lam.) Pers. or in the leaves of the inducible CAM plant Mesembryanthemum crystallinum L.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00393908
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  • 3
    Digitale Medien
    Digitale Medien
    The influence of inorganic phosphate on photosynthesis in intact chloroplasts from Mesembryanthemum crystallinum L. plants exhibiting C3 photosynthesis or crassulacean acid metabolism (1983)
    Springer
    Planta 159 (1983), S. 97-104 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Crassulacean acid metabolism ; Mesembryanthemum ; Chloroplast, isolated ; Photosynthesis (O2 evolution, CO2 fixation)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Intact chloroplasts were obtained from mesophyll protoplasts isolated from Mesembryanthemum crystallinum in the C3 or Crassulacean acid metabolism (CAM) photosynthetic mode, and examined for the influence of inorganic phosphate (Pi) on aspects of bicarbonate-dependent O2 evolution and CO2 fixation. While the chloroplasts from both modes responded similarly to varying Pi, some features appear typical of chloroplasts from species capable of CAM, including a relatively high capacity for photosynthesis in the absence of Pi, a short induction period, and resistance to inhibition of photosynthesis by high levels of Pi. In the absence of Pi the chloroplasts retained 75–85% of the 14CO2 fixed and the total export of dihydroxyacetone phosphate was low compared with the rate of photosynthesis. In CAM plants the ability to conduct photosynthesis and retain most of the fixed carbon in the chloroplasts at low external Pi concentrations may enable storage of carbohydrates which are essential for providing a carbon source for the nocturnal synthesis of malic acid. At high external Pi concentrations (e.g. 10 25 mM), the amount of total dihydroxyacetone phosphate exported to the assay medium relative to the rate of photosynthesis was high while the products of 14CO2 fixation were largely retained in the chloroplasts which indicates starch degradation is occurring at high Pi levels. Starch degradation normally occurs in CAM plants in the dark; high levels of Pi may induce starch degradation in the light which has the effect of limiting export of the immediate products of photosynthesis and thus the degree of Pi inhibition of photosynthesis with the isolated chloroplast.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00392978
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  • 4
    Digitale Medien
    Digitale Medien
    Effects of growth regulators on the induction of Crassulacean acid metabolism in the facultative halophyte Mesembryanthemum crystallinum L. (1994)
    Springer
    Planta 192 (1994), S. 287-294 
    Details
    ISSN: 1432-2048
    Schlagwort(e): Crassulacean acid metabolism ; Growth regulator ; Induction of CAM ; Mesembryanthemum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The classical induction of Crassulacean acid metabolism (CAM) in Mesembryanthemum crystallinum L. by water stress is observed within one week when fourto five-week-old plants (grown under a 16/8 h photoperiod at ca. 600 μmol quanta · m−2 · s−1) are irrigated with 350 mM NaCl. The induction of CAM was evaluated by measuring phosphoenolpyruvate carboxylase (PEPCase, EC 4.1.1.31) and NADP-malic enzyme (NADP-ME, EC 4.1.1.82) activities and nocturnal increases in malate content and titratable acidity of leaf extracts, and the daily pattern of CO2 exchange and stomatal conductance during the 7-d induction period. Three growth regulators, abscisic acid (ABA), farnesol (an antitranspirant and analog of ABA), and benzylaminopurine (BAP), were found to substitute for NaCl for induction of CAM when fed to plants in nutrient media. Daily irrigation with solutions containing micromolar levels (optimum ca. 10 micromolar) of these growth regulators led to the induction of CAM similar to that by high salt. Application of the growth regulators, like NaCl, caused large increases in the activity of NADP-ME and the activity and level of PEPCase, which are components of the biochemical machinery required for CAM. Western immunoblotting showed that the increased activity of PEPCase on addition of ABA, farnesol and BAP was mainly due to increased levels of the CAM-specific isoforms. Also, dehydration of cut leaves over 8.5 h under light resulted in a severalfold increase in PEPCase activity. An equivalent increase in PEPCase activity in excised leaves was also obtained by feeding 150 mM NaCl, or micromolar levels of ABA or BAP via the petiole, which supports results obtained by feeding the growth regulators to roots. However, the increase in PEPCase activity was inhibited by feeding high levels of BAP to cut leaves prior to dehydration, indicating a more complex response to the cytokinin. Abscisic acid may have a role in induction of CAM in M. crystallinum under natural conditions as there is previous evidence that induction by NaCl causes an increase in the content of ABA, but not cytokinins, in leaves of this species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00198562
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  • 5
    Digitale Medien
    Digitale Medien
    Inhibition of C4 photosynthesis by (benzamidooxy)acetic acid (1982)
    Springer
    Photosynthesis research 3 (1982), S. 293-305 
    Details
    ISSN: 1573-5079
    Schlagwort(e): aspartate and alanine aminotransferases ; (benzamidooxy)acetic acid ; C4 photosynthesis ; herbicide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract (Benzamidooxy)acetic acid (common name benzadox) which has herbicidal properties was evaluated as a potential inhibitor of photosynthesis in C4 plants. Among enzymes of the C4 pathway, it was a relatively strong inhibitor of alanine aminotransferase in in vitro experiments at concentrations of 5mM. In benzadox treated leaves of Panicum miliaceum, a NAD-malic enzyme type C4 species, there was strong inhibition of both alanine and aspartate aminotransferase and of photosynthetic O2 evolution within one hour. Consistent with the inhibition of these enzymes of the C4 cycle, the pool sizes of metabolites of the cycle was altered: the aspartate level was increased two fold, while the levels of other metabolites such as pyruvate, alanine, oxalacetate and malate were decreased. Kinetic studies with partially purified alanine aminotransferase showed that benzadox is a competitive inhibitor with respect to alanine and a noncompetitive inhibitor with respect to 2-oxoglutarate. Comparisons between the structures and inhibitory actions of benzadox and (aminooxy)acetic acid, the latter a potent inhibitor of alanine and aspartate aminotransferases, suggest that in vivo, benzadox may exert its effect through metabolism to (aminooxy)acetic acid.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00034110
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  • 6
    Digitale Medien
    Digitale Medien
    Can CO2 assimilation in maize leaves be predicted accurately from chlorophyll fluorescence analysis? (1993)
    Springer
    Photosynthesis research 37 (1993), S. 89-102 
    Details
    ISSN: 1573-5079
    Schlagwort(e): C4 photosynthesis ; chlorophyll fluorescence ; CO2 assimilation ; maize ; Photosystem II ; quantum yield
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Analysis is made of the energetics of CO2 fixation, the photochemical quantum requirement per CO2 fixed, and sinks for utilising reductive power in the C4 plant maize. CO2 assimilation is the primary sink for energy derived from photochemistry, whereas photorespiration and nitrogen assimilation are relatively small sinks, particularly in developed leaves. Measurement of O2 exchange by mass spectrometry and CO2 exchange by infrared gas analysis under varying levels of CO2 indicate that there is a very close relationship between the true rate of O2 evolution from PS II and the net rate of CO2 fixation. Consideration is given to measurements of the quantum yields of PS II (φ PS II) from fluorescence analysis and of CO2 assimilation ( $$\phi _{CO_2 } $$ ) in maize over a wide range of conditions. The $${{\phi _{PSII} } \mathord{\left/ {\vphantom {{\phi _{PSII} } {\phi _{CO_2 } }}} \right. \kern-\nulldelimiterspace} {\phi _{CO_2 } }}$$ ratio was found to remain reasonably constant (ca. 12) over a range of physiological conditions in developed leaves, with varying temperature, CO2 concentrations, light intensities (from 5% to 100% of full sunlight), and following photoinhibition under high light and low temperature. A simple model for predicting CO2 assimilation from fluorescence parameters is presented and evaluated. It is concluded that under a wide range of conditions fluorescence parameters can be used to predict accurately and rapidly CO2 assimilation rates in maize.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02187468
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  • 7
    Digitale Medien
    Digitale Medien
    Light/dark modulation of phosphoenolpyruvate carboxylase in C3 and C4 species (1994)
    Springer
    Photosynthesis research 42 (1994), S. 133-143 
    Details
    ISSN: 1573-5079
    Schlagwort(e): PEP carboxylase ; C3 ; C4
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In this report, the effects of light on the activity and allosteric properties of phosphoenolpyruvate (PEP) carboxylase were examined in newly matured leaves of several C3 and C4 species. Illumination of previously darkened leaves increased the enzyme activity 1.1 to 1.3 fold in C3 species and 1.4 to 2.3 fold in C4 species, when assayed under suboptimal conditions (pH 7) without allosteric effectors. The sensitivities of PEP carboxylase to the allosteric effectors malate and glucose-6-phosphate were markedly different between C3 and C4 species. In the presence of 5 mM malate, the activity of the enzyme extracted from illuminated leaves was 3 to 10 fold higher than that from darkened leaves in C4 species due to reduced malate inhibition of the enzyme from illuminated leaves, whereas it increased only slightly in C3 species. The Ki(malate) for the enzyme increased about 3 fold by illumination in C4 species, but increased only slightly in C3 species. Also, the addition of the positive effector glucose-6-phosphate provided much greater protection against malate inhibition of the enzyme from C4 species than C3 species. Feeding nitrate to excised leaves of nitrogen deficient plants enhanced the degree of light activation of PEP carboxylase in the C4 species maize, but had little or no effect in the C3 species wheat. These results suggest that post-translational modification by light affects the activity and allosteric properties of PEP carboxylase to a much greater extend in C4 than in C3 species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02187124
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  • 8
    Digitale Medien
    Digitale Medien
    CO2 and O2 dependence of PS II activity in C4 plants having genetically produced deficiencies in the C3 or C4 cycle (1998)
    Springer
    Photosynthesis research 58 (1998), S. 91-101 
    Details
    ISSN: 1573-5079
    Schlagwort(e): C4 photosynthesis ; PEP carboxylase mutants ; Photosystem II ; Rubisco transgenic plants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The CO2 dependence of rates of CO2 fixation (A) and photochemistry of PS II at 5, 15 and 30% O2 were analyzed in the C4 plant Amaranthus edulis having a C4 cycle deficiency [phosphoenolpyruvate carboxylase (PEPC) mutants], and in the C4 plant Flaveria bidentis having a C3 cycle deficiency [Rubisco small subunit antisense (αSSU)]. In the wild type (WT) A. edulis and its heterozygous mutant having less than 50% WT PEPC activity there was a similar dependence of A and PS II photochemistry on varying CO2, although the CO2 saturated rates were 25% lower in heterozygous plants. The homozygous plants having less than 2% PEPC of the WT had significant levels of photorespiration at ambient levels of CO2 and required about 30 times ambient levels for maximum rates of A. Despite variation in the capacity of the C4 cycle, more than 91% of PS II activity was linearly associated with A under varying CO2 at 5, 15 and 30% O2. However, the WT plant had a higher PS II activity per CO2 fixed under saturating CO2 than the homozygous mutant, which is suggested to be due to elimination of the C4 cycle and its associated requirement for ATP from a Mehler reaction. In the αSSU F. bidentis plants, a decreased rate of A (35%) and PS II activity (33%) accompanied a decrease in Rubisco capacity. There was some increase in alternative electron sinks at high CO2 when the C3 cycle was constrained, which may be due to increased flux through the C4 cycle via an ATP generating Mehler reaction. Nevertheless, even with constraints on the function of the C4 or C3 cycle by genetic modifications, analyses of CO2 response curves under varying levels of O2 indicate that CO2 assimilation is the main determinant of PS II activity in C4 plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006176713574
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  • 9
    Digitale Medien
    Digitale Medien
    A mathematical model of C4 photosynthesis: The mechanism of concentrating CO2 in NADP-malic enzyme type species (2000)
    Springer
    Photosynthesis research 66 (2000), S. 199-224 
    Details
    ISSN: 1573-5079
    Schlagwort(e): C4 photosynthesis ; modeling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A computer model comprising light reactions in PS II and PS I, electron-proton transport reactions in mesophyll and bundle sheath chloroplasts, all enzymatic reactions and most of the known regulatory functions of NADP-ME type C4 photosynthesis has been developed as a system of differential budget equations for intermediate compounds. Rate-equations were designed on principles of multisubstrate-multiproduct enzyme kinetics. Some of the 275 constants needed (ΔG0′ and K m values) were available from literature and others (V m) were estimated from reported rates and pool sizes. The model provided good simulations for rates of photosynthesis and pool sizes of intermediates under varying light, CO2 and O2. A basic novelty of the model is coupling of NADPH production via NADP-ME with ATP production and regulation of the C3 cycle in bundle sheath chloroplasts. The functional range of the ATP/NADPH ratio in bundle sheath chloroplasts extends from 1.5 to 2.1, being energetically most efficient around 2. In the presence of such stoichiometry, the CO2 concentrating function can be explained on the basis of two processes: (a) extra ATP consumption for starch and protein synthesis in bundle sheath leads to a faster NADPH and CO2 import compared with CO2 fixation in bundle sheath, and (b) the residual photorespiratory activity consumes RuBP by oxygenation, NADPH and ATP and causes the imported CO2 to accumulate in bundle sheath cells. As a wider application, the model may be used for predicting results of genetic engineering of plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1010695402963
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  • 10
    Digitale Medien
    Digitale Medien
    Light and temperature dependence of the rate and degree of activation of pyruvate, Pi dikinase in vivo in maize (1980)
    Springer
    Photosynthesis research 1 (1980), S. 199-207 
    Details
    ISSN: 1573-5079
    Schlagwort(e): C4 photosynthesis ; maize ; pyruvate ; Pi dikinase ; temperature and light
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Activation of pyruvate,Pi dikinase by light was studied in leaf discs of maize which were illuminated for 1 h at light intensities ranging from approximately 3% to 50% of full sunlight and at temperatures of 10, 22.5, and 35°C. At the highest light intensity the degree of activation was similar and relatively independent of temperature between 10 and 35°C. Under low light the degree of activation was high at 10°C but decreased rapidly with increasing temperature. There was a similar effect of light and temperature on the activation of NADP-malate dehydrogenase. At low temperature, the rate of activation of pyruvate,Pi dikinase was relatively low and independent of the light intensity used and the rate of inactivation in the dark was extremely low. At high temperature, the rate of activation was high and dependent on the light intensity used while the rate of dark inactivation was also relatively high. The degree of activation is discussed in relation to the possible influence of light and temperature on the turnover between the active and inactive forms of pyruvate,Pi dikinase during illumination.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020599
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