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  • Artikel: DFG Deutsche Nationallizenzen  (8)
  • C3 plants  (3)
  • Mesembryanthemum  (3)
  • C3  (2)
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  • Artikel: DFG Deutsche Nationallizenzen  (8)
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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    Digitale Medien
    Digitale Medien
    Effects of polyploidy on photosynthesis (1993)
    Springer
    Photosynthesis research 35 (1993), S. 135-147 
    Details
    ISSN: 1573-5079
    Schlagwort(e): C3 plants ; C4 plants ; DNA ; photosynthesis ; polyploidy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In polyploid plants the photosynthetic rate per cell is correlated with the amount of DNA per cell. The photosynthetic rate per unit leaf area is the product of the rate per cell times the number of photosynthetic cells per unit area. Therefore, the photosynthetic rate per unit leaf area will increase if there is a less than proportional increase in cell volume at higher ploidal levels, or if cell packing is altered to allow more cells per unit leaf area. In autopolyploids (Medicago sativa, C3 species, and Pennisetum americanum, C4 species) there is a doubling of photosynthesis per cell and of cell volume in the tetraploid compared to the diploid. However, there is a proportional decrease in number of cells per unit leaf area with this increase in ploidy such that the rate of photosynthesis per leaf area does not change. There is more diversity in the relationship between ploidal level (gene dosage) and photosynthetic rates per unit leaf area in allopolyploids. This is likely to reflect the effects of natural selection on leaf anatomy, and novel genetic interactions from contributed genomes which can occur with allopolyploidy. In allopolyploid wheat (C3 species) a higher cell volume per unit DNA at the higher ploidal level is negatively correlated with photosynthesis rate per unit leaf area. Although photosynthesis per cell increases with ploidy, photosynthesis per leaf area decreases, being lowest in the allohexaploid, cultivated bread wheat (Triticum aestivum). Alternatively, doubling of photosynthetic rate per cell with doubling of DNA, with apparent natural selection for decreased cell volume per unit DNA, results in higher rates of photosynthesis per leaf area in octaploid compared to tetraploid Panicum virgatum (C4) which may be a case of allopolyploidy. Similar responses probably occur in Festuca arundinacea. Therefore, in some systems anatomical factors affecting photosynthesis are also affected by ploidal level. It is important to evaluate that component as well as determining the effect on biochemical processes. Current information on polyploidy and photosynthesis in several species is discussed with respect to anatomy, biochemistry and bases for expressing photosynthetic rates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00014744
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  • 6
    Digitale Medien
    Digitale Medien
    Light dependence of quantum yields of Photosystem II and CO2 fixation in C3 and C4 plants (1993)
    Springer
    Photosynthesis research 35 (1993), S. 265-274 
    Details
    ISSN: 1573-5079
    Schlagwort(e): C3 plants ; C4 plants ; light ; Photosystem II ; quantum yield ; fluorescence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The light dependence of quantum yields of Photosystem II (ΦII) and of CO2 fixation were determined in C3 and C4 plants under atmospheric conditions where photorespiration was minimal. Calculations were made of the apparent quantum yield for CO2 fixation by dividing the measured rate of photosynthesis by the absorbed light [A/I=ΦCO2 and of the true quantum yield by dividing the estimated true rate of photosynthesis by absorbed light [(A+Rl)/Ia=ΦCO2·], where RL is the rate of respiration in the light. The dependence of the ΦII/ΦCO2 and ΦII/ΦCO2 * ratios on light intensity was then evaluated. In both C3 and C4 plants there was little change in the ratio of ΦII/ΦCO2 at light intensities equivalent to 10–100% of full sunlight, whereas there was a dramatic increase in the ratio at lower light intensities. Changes in the ratio of ΦII/ΦCO2 can occur because respiratory losses are not accounted for, due to changes in the partitioning of energy between photosystems or changes in the relationship between PS II activity and CO2 fixation. The apparent decrease in efficiency of utilization of energy derived from PS II for CO2 fixation under low light intensity may be due to respiratory loss of CO2. Using dark respiration as an estimate of RL, the calculated ΦII/ΦCO2 * ratio was nearly constant from full sunlight down to approx 5% of full sunlight, which suggests a strong linkage between the true rate of CO2 fixation and PS II activity under varying light intensity. Measurements of photosynthesis rates and ΦII were made by illuminating upper versus lower leaf surfaces of representative C3 and C4 monocots and dicots. With the monocots, the rate of photosynthesis and the ratio of ΦII/ΦCO2 exhibited a very similar patterns with leaves illuminated from the adaxial versus the abaxial surface, which may be due to uniformity in anatomy and lack of differences in light acclimation between the two surfaces. With dicots, the abaxial surface had both lower rates of photosynthesis and lower ΦII values than the adaxial surface which may be due to differences in anatomy (spongy versus palisade mesophyll cells) and/or light acclimation between the two surfaces. However, in each species the response of ΦII/ΦCO2 to varying light intensity was similar between the two surfaces, indicating a comparable linkage between PS II activity and CO2 fixation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00016557
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  • 7
    Digitale Medien
    Digitale Medien
    Analysis of inhibition of photosynthesis due to water stress in the C3 species Hordeum vulgare and Vicia faba: Electron transport, CO2 fixation and carboxylation capacity (1996)
    Springer
    Photosynthesis research 49 (1996), S. 57-69 
    Details
    ISSN: 1573-5079
    Schlagwort(e): water stress ; C3 plants ; chlorophyll fluorescence ; Rubisco ; CO2 exchange
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A C3 monocot, Hordeum vulgare and C3 dicot, Vicia faba, were studied to evaluate the mechanism of inhibition of photosynthesis due to water stress. The net rate of CO2 fixation (A) and transpiration (E) were measured by gas exchange, while the true rate of O2 evolution (J O2) was calculated from chlorophyll fluorescence analysis through the stress cycle (10 to 11 days). With the development of water stress, the decrease in A was more pronounced than the decrease in J O2 resulting in an increased ratio of Photosystem II activity per CO2 fixed which is indicative of an increase in photorespiration due to a decrease in supply of CO2 to Rubisco. Analyses of changes in the J O2 A ratios versus that of CO2 limited photosynthesis in well watered plants, and RuBP pool/RuBP binding sites on Rubisco and RuBP activity, indicate a decreased supply of CO2 to Rubisco under both mild and severe stress is primarily responsible for the decrease in CO2 fixation. In the early stages of stress, the decrease in C i (intercellular CO2) due to stomatal closure can account for the decrease in photosynthesis. Under more severe stress, CO2 supply to Rubisco, calculated from analysis of electron flow and CO2 exchange, continued to decrease. However, C i, calculated from analysis of transpiration and CO2 exchange, either remained constant or increased which may be due to either a decrease in mesophyll conductance or an overestimation of C i by this method due to patchiness in conductance of CO2 to the intercellular space. When plants were rewatered after photosynthesis had dropped to 10–30% of the original rate, both species showed near full recovery within two to four days.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00029428
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  • 8
    Digitale Medien
    Digitale Medien
    Malate metabolism by NADP-malic enzyme in plant defense (1999)
    Springer
    Photosynthesis research 61 (1999), S. 99-105 
    Details
    ISSN: 1573-5079
    Schlagwort(e): C3 ; C4 ; UV-B ; stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Malate is involved in various metabolic pathways, and there are several enzymes that metabolize it. One important malate metabolizing enzyme is NADP-malic enzyme (NADP-ME). NADP-ME functions in many different pathways in plants, having an important role in C4 photosynthesis where it releases the CO2 to be used in carbon fixation by Rubisco. Apart from this specialized role, NADP-ME is thought to fulfill diverse housekeeping functions because of its universal presence in different plant tissues. NADP-ME is induced after wounding or exposure to UV-B radiation. In this way, the enzyme is implicated in defense-related deposition of lignin by providing NADPH for the two NADPH-dependent reductive steps in monolignol biosynthesis. On the other hand, it can supply NADPH for flavonoid biosynthesis as many steps in the flavonoid biosynthesis pathway require reductive power. Pyruvate, another product of NADP-ME reaction, can be used for obtaining ATP through respiration in the mitochondria; and may serve as a precursor for synthesis of phosphoenolpyruvate (PEP). PEP is utilized in the shikimate pathway, leading to the synthesis of aromatic amino acids including phenylalanine, the common substrate for lignin and flavonoid synthesis. Moreover, NADP-ME can be involved in mechanisms producing NADPH for synthesis of activated oxygen species that are produced in order to kill or damage pathogens. In conclusion, an increase in the levels of NADP-ME could provide building blocks and energy for biosynthesis of defense compounds, suggesting a role of malate metabolism in plant defense.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1006209003096
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