Dicarboxylic Acid Pathway Of Photosynthesis Research Articles

Analyzing the Light Energy Distribution in the Photosynthetic Apparatus of C4 Plants Using Highly Purified Mesophyll and Bundle-Sheath Thylakoids.

The chlorophyll fluorescence characteristics of mesophyll and bundle-sheath thylakoids from plant species with the C4 dicarboxylic acid pathway of photosynthesis were investigated using flow cytometry. Ten species with the NADP-malic enzyme (NADP-ME) biochemical type of C4 photosynthesis were tested: Digitaria sanguinalis (L.) Scop., Euphorbia maculata L., Portulaca grandiflora Hooker, Saccharum officinarum L., Setaria viridis (L.) Beauv., Zea mays L., and four species of the genus Flaveria. This study also included three species with NAD-ME biochemistry (Atriplex rosea L., Atriplex spongiosa F. Muell., and Portulaca oleracea L.). Two C4 species of unknown biochemical type were investigated: Cyperus papyrus L. and Atriplex tatarica L. Pure mesophyll and bundle-sheath thylakoids were prepared by flow cytometry and characterized by low-temperature fluorescence spectroscopy. In pure bundle-sheath thylakoids from many species with C4 photosynthesis of the NADP-ME type, significant amounts of photosystem II (PSII) emission can be detected by fluorescence spectroscopy. Simulation of fluorescence excitation spectra of these thylakoids showed that PSII light absorption contributes significantly to the apparent excitation spectrum of photosystem I. Model calculations indicated that the excitation energy of PSII is efficiently transferred to photosystem I in bundle-sheath thylakoids of many NADP-ME species.

Photosynthetic carbon metabolism in Panicum milioides, a C 3-C 4 intermediate species: Evidence for a limited C 4 dicarboxylic acid pathway of photosynthesis

Panicum milioides, a naturally occurring species with C 4-like Kranz leaf anatomy, is intermediate between C 3 and C 4 plants with respect to photorespiration and the associated oxygen inhibition of photosynthesis. This paper presents direct evidence for a limited degree of C 4 photosynthesis in this C 3-C 4 intermediate species based on: 1. (a) the appearance of 24% of the total 14C fixed following 4 s photosynthesis in 14CO 2-air by excised leaves in malate and aspartate and the complete transfer of label from the C 4 acids to Calvin cycle intermediates within a 15 s chase in 12CO 2-air; 2. (b) pyruvate- or alanine-enhanced light-dependent CO 2 fixation and pyruvate stimulation of oxaloacetate- or 3-phosphoglycerate-dependent O 2 evolution by illuminated mesophyll protoplasts, but not bundle sheath strands; and 3. (c) NAD-malic enzyme-dependent decarboxylation of C 4 acids at the C-4 carboxyl position, C 4 acid-dependent O 2 evolution, and 14CO 2 donation from [4- 14C]C 4 acids to Calvin cycle intermediates during photosynthesis by bundle sheath strands, but not mesophyll protoplasts. However, P. milioides differs from C 4 plants in that the activity of the C 4 cycle enzymes is only 15 to 30% of a C 4 Panicum species and the Calvin cycle and phospho enolpyruvate carboxylase are present in both cell types. From these and related studies (Rathnam, C.K.M. and Chollet, R. (1979) Arch. Biochem. Biophys. 193, 346–354; (1978) Biochem. Biophys. Res. Commun. 85, 801–808) we conclude that reduced photorespiration in P. milioides is due to a limited degree of NAD-malic enzyme-type C 4 photosynthesis permitting an increase in pCO 2 at the site of bundle sheath, but not mesophyll, ribulosebisphosphate carboxylase-oxygenase.

Ecological evidence concerning the adaptive significance of the C4 dicarboxylic acid pathway of photosynthesis.

Ecological data were analyzed to determine the environmental conditions associated with the occurrence of plants possessing C3 and C4 photosynthetic pathways. Non-parametric analysis of variance, multiple regression analysis and discriminant analysis techniques were applied to information derived from separate studies on plant species in California and central Europe. All the analyses revealed significant differences in ecology between the C3 and C4 groups. The occurrence of C4 species was greater where summer or winter temperatures were relatively high and moisture availability relatively low. Using discriminant analysis, more than 80% of the species considered were classified into the correct photosynthetic category on the basis of their distribution with respect to temperature. No significant differences between the C3 and C4 groups were found for other environmental factors, including light, soil nitrogen, soil salinity and continentality of climate. These results support the suggestion from previous physiological studies that C4 species may possess competitive advantages under conditions of high temperature and intermittent water stress. The C4 species were relatively restricted in the range of environmental conditions where they occurred, and as a group C4 species may be ecologically more specialized than C3 species.

13C Content of human collagen as a measure of prehistoric diet in woodland North America

PLANTS with the C4 dicarboxylic acid pathway of photosynthesis have markedly higher 13C/12C ratios than plants with the C3 or Calvin pathway1–4. Cumulative assessments of relative 13C concentration (δ13C) values for C3 plant foliage yield an average of −26.5‰, relative to the PDB standard whereas C4 plants average −12.5‰ (ref. 5). These differences in carbon isotope ratios are passed along the food chain to animals and man, so that the nature of the plant food base can be determined through measurements on different body tissues of the consumers. In this study, the time of introduction of maize, a C4 plant, to the prehistoric inhabitants of several regions in woodland North America, almost exclusively a C3 plant regime, was determined through isotopic measurements on human bone collagen. The subsequent elevation of maize to the level of a diet staple is also documented.

Endogenous Photophosphorylation by Mesophyll and Bundle Sheath Chloroplasts from Setaria italica and Amaranthus paniculatus1

The basic features of the C4 dicarboxylic acid pathway of photosynthesis are the fixation of carbon dioxide into C4 acids (namely oxalacetate, malate and aspartate) in the mesophyll cells and their transport into the bundle sheath cells where they are decarboxylated. Thus released carbon dioxide is refixed and further metabolized via the Calvin cycle in the sheath cells (Hatch and Slack, 1970; Black, 1973). Such two-step carboxylation is calculated to result in an energy cost of 5 ATP and 2 NADPH2 per molecule of C02 fixed, compared to that of 3 ATP and 2 NADPH2 per each C02 molecule reduced through Calvin cycle alone (Chen, Brown and Black, 1969; Hatch and Slack, 1970). Chen et al. (1969) suggested that the extra requirement of ATP in C4 plants is met with the capacities of C4 plant-chloroplasts to catalyze higher rates of cyclic photophosphorylation. Bundle sheath chloroplasts of C4 plants, producing malate as the principal C4 acid, e.g., maize and sorghum, are deficient in photosystem (PS) II compared to PS I (Anderson, Woo and Boardman, 19716; Downton, 1971 ; Mayne, Edwards and Black, 1971). Such PS II deficiency has important consequences for Calvin cycle metabolism in the bundle sheath cells of these plants, since all the carbon fixed during photosynthesis eventually has to be reduced through the Calvin cycle. In such instances, it is proposed that for normal C02 reduction, NADPH2 is provided by malic enzyme (Slack, Hatch and Goodchild, 1969; Downton, 1971) and ATP is supplied through cyclic photophosphorylation (Chen et al ., 1969 ; Slack et al ., 1969). These complications do not arise with other C4 plants which use aspartate as the major C4 acid (e.g. Amaranthus and Atriplex ) where bundle sheath chloroplasts possess an active PS II as well as PS I. Though the studies on mesophyll and bundle sheath chloroplasts showed high cyclic photophosphorylation (mediated through phenazine methosulphate) capacities of bundle sheath chloroplast fragments (Anderson, Boardman and Spencer, 1971a; Polya and Osmond, 1972), convincing evidence for endogenous cyclic photophosphorylation is still not available. Here we report the presence of an active endogenous photophosphorylation of bundle sheath chloroplasts insensitive to 3(3,4-dichlorophenyl)-l,l-dimethyl urea (DCMU), evidently mediated through PS I. Plants of Setaria italica Beauv. var. H-l and Amaranthus paniculatus L. were raised in seed pans under an approximate 12-h photoperiod (35 °C day and 20 °C night). The second to fourth leaves starting from the oldest leaf were picked from 3 to 4 week old seedlings. The leaves were chilled to 0 °C and cut into pieces of c. 1 cm2. Mesophyll and bundle sheath chloroplasts were prepared by differential grinding of leaf tissue (Raghavendra, 1975;

C4 pathway of photosynthesis in a member of the polygonaceae: Calligonum persicum(Boiss. & Buhse) boiss

Summary Initial products of 14CO2 fixation, CO2 compensation point and carbon isotope discrimination indicate the occurrence of the C4 dicarboxylic acid pathway of photosynthesis in Calligonum persicum. In this species, the green centric branches do not have the typical form of Kranz-anatomy with a concentric arrangement of mesophyll and bundle sheath layers around the vascular bundles. Instead, they possess two distinct, peripheral rings of green cells. Small vascular bundles adjoin the internal face of the inner layer of green cells, but only at intervals.

Light-Enhanced Dark 14CO2 Fixation by Leaves in Relation to the C4 Dicarboxylic Acid Pathway of Photosynthesis

The technique of light-enhanced dark carbon dioxide fixation has been employed to critically examine the primary route of CO2 incorporation in leaves of two C4 plants (Setaria italica and Amaranthus paniculatus) in comparison with that of a C3 plant (Rumex vesicarius). Prior illumination of detached leaves enhanced their dark 14CO2 fixation five- to tenfold over that of unilluminated leaves. No variation was observed among C3 and C4 plants, in the conditions required for their light-enhanced dark fixation. Fifty to sixty percent of initially incorporated radioactivity by the leaves of R. vesicarius was in 3-phosphoglycerate. The leaves of S. italica and A. paniculatus fixed most of the radioactivity into the C4 acids malate and aspartate. Sugar phosphates, including 3-phosphoglycerate, were not labelled at all. Our data confirm that, in C4 plants, CO2 is initially fixed through phosphoenolpyruvate carboxylation and thus disprove earlier claims that ribulose bisphosphate can be the primary acceptor of CO2 in a C4 plant. The observations further suggested that aspartate formation during carbon fixation might be favoured by illumination.

A high-activity ATP translocator in mesophyll chloroplasts of Digitaria sanguinalis, a plant having the C-4 dicarboxylic acid pathway of photosynthesis

The effect of exogenous adenine nucleotides on CO 2 fixation and oxygen evolution was studied with mesophyll protoplast extracts of the C 4 plant Digitaria sanguinalis. Exogenous ATP was found to stimulate the rate of pyruvate and pyruvate + oxalacetate induced CO 2 fixation, as well as reverse the inhibition of CO 2 fixation by carbonyl cyanide m-chlorophenyl hydrazone and several electron transport inhibitors. The ATP-dependent stimulation of CO 2 fixation varied from 40 to 70 μmol CO 2 fixed/mg chlorophyll per h, suggesting that ATP was crossing the chloroplast membranes at rates of 80–140 μmol/mg chlorophyll per h, since 2 ATP are required for each CO 2 fixed. Fixation of CO 2 could also be induced in the dark by exogenous ATP, in which case ADP accumulated outside the chloroplasts. This suggests that external ATP is exchanging for internal ADP. In contrast, ADP and AMP were found not to traverse chloroplast membranes, on the basis that neither nucleotide inhibited CO 2 fixation or stimulated oxygen evolution that was limited by available ADP for phosphorylation. Further evidence that ATP can enter the chloroplasts was obtained by direct measurements of the increase in ATP in the chloroplasts due to addition of exogenous ATP in the dark. These studies yielded minimal rates of ATP uptake on the order of 30–40 μmol/mg chlorophyll per h. It is suggested that a membrane translocator exists that specifically transports ATP into the chloroplasts in exchange for ADP. The significance of these findings are considered with respect to the C 4 pathway of photosynthesis.

The action of sulfite on the HCO3−-fixation and the fixation pattern of isolated chloroplasts and leaf tissue slices

Summary Light dependent HCO 3 − -fixation, showing an apparent K m (HC0 3 − ) of 1.3 mM, is competitively inhibited by sulfite. The kinetic analysis indicates that the over-all reaction consists of two processes, both of which are inhibited in a fully competitive way, but with different K i values (1.6 mM and 0.9 mM SO 3 − - respectively). By the action of sulfite, the CO 2 -fixation pattern of isolated spinach chloroplasts is shifted towards the intermediates of the C 4 -dicarboxylic acid pathway of photosynthesis. A similar shift is brought about, although less markedly, by the effect of leaf slicing alone. In maize leaf slices sulfite causes a decrease in malate formation, which is accompanied by an increase in aspartate. Glycollate is accumulated, and as a consequence, label in serine and glycine is reduced. The accumulation is not only due to the inhibition of glycollate oxidase, but also due to an enhanced synthesis in the chloroplasts. Several data on the inhibitory action of sulfite towards the enzymes involved are represented, which may explain the changes in fixation pattern.

Metabolic regulation in C4 photosynthesis: PEP-carboxylase and energy charge

The effects of ATP, ADP and AMP on the activity of PEP carboxylase from Pennisetum purpureum (a C4 plant) have been investigated. AMP caused slight changes in activity. Both ATP and ADP were inhibitory. The extent of inhibition was related to the concentration of Mg(2+). Kinetics of inhibition (with PEP as variable substrate) were investigated at limiting concentrations of Mg(2+) (2 mM); with excess Mg(2+) (5 mM); or with the concentration of Mg(2+) buffered at about 8 mM. At low Mg(2+) parabolic competitive-kinetics were observed. With higher Mg(2+) concentration linear competitive kinetics of inhibition were observed with a K i (slope) of 1.25 mM ATP. This was increased to 2.03 mM on addition of the allosteric activator glucose-6-P (5 mM). With Mg(2+) buffered ATP was an activator at low concentrations of PEP.Response to enegery charge was investigated using either calculated concentrations of all adenylates or mixtures of AMP and ATP pre-incubated with adenylate kinase. Inhibition at high charge could be reduced by increasing the concentration of Mg(2+) or by addition of the activator glucose-6-P. With enzyme-generated charge series and Mg(2+) buffered at 8 mM an increase in activity was observed at high charge values.These results are discussed in terms of a possible regulatory role of adenylates in the C4 dicarboxylic acid pathway of photosynthesis.

A screening of the dicotyledonous weed flora for the occurrence of C4 dicarboxylic acid pathway of photosynthesis

Using the criteria of leaf anatomy, carbon dioxide compensation point and photosynthetic rate under reduced oxygen tension, a number of the local herbaceous and dicotyledonous weeds were screened for the occurrence of the C4 pathway of photosynthesis. Of the thirty-two species, belonging to nine families seventeen species revealed the characteristics of the C4 plants. All of the plants surveyed here were hitherto not tested and therefore the present results extend the number of plants already known to possess the Hatch-Slack pathway of photosynthesis. Another noteworthy feature of the investigation was the finding of interspecific differences within the generaHeliotropium, Alternanthera, Mollugo andEuphorbia in the presence or absence of the C4 pathway.

Metabolic Activities in Extracts of Mesophyll and Bundle Sheath Cells of Panicum miliaceum (L.) in Relation to the C4 Dicarboxylic Acid Pathway of Photosynthesis

The activities of certain enzymes related to the carbon assimilation pathway in whole leaves, mesophyll cell extracts, and bundle sheath extracts of the C(4) plant Panicum miliaceum have been measured and compared on a chlorophyll basis. Enzymes of the C(4) dicarboxylic acid pathway-phosphoenolpyruvate carboxylase and NADP-malic dehydrogenase-were localized in mesophyll cells. Carbonic anhydrase was also localized in mesophyll cell extracts. Ribose 5-phosphate isomerase, ribulose 5-phosphate kinase, and ribulose diphosphate carboxylase-enzymes of the reductive pentose phosphate pathway-were predominantly localized in bundle sheath extracts. High activities of aspartate and alanine transaminases and glyceraldehyde-3-P dehydrogenase were found about equally distributed between the photosynthetic cell types. P. miliaceum had low malic enzyme activity in both mesophyll and bundle sheath extracts.Isolated bundle sheath cells were capable of converting aspartate to oxalacetate at rates approaching the aspartate transaminase activity of bundle sheath extracts. The bundle sheath cells had a light induced CO(2) fixation of 23 mumoles of CO(2)/mg chl.hr in the absence of exogenous substrates.The photorespiratory enzymes, hydroxypyruvate reductase and glycolic oxidase, were about 3 fold higher in bundle sheath extracts than in mesophyll extracts when compared on a chlorophyll basis.

Metabolic regulation in the C4 dicarboxylic acid pathway of photosynthesis.

Research Article| November 01 1972 Metabolic regulation in the C4 dicarboxylic acid pathway of photosynthesis J Coombs; J Coombs 1Tate and Lyle Ltd. Research Centre, Westerham Road, Keston, Kent BR2 6HJ, U.K Search for other works by this author on: This Site PubMed Google Scholar C W Baldry; C W Baldry 1Tate and Lyle Ltd. Research Centre, Westerham Road, Keston, Kent BR2 6HJ, U.K Search for other works by this author on: This Site PubMed Google Scholar C Bucke C Bucke 1Tate and Lyle Ltd. Research Centre, Westerham Road, Keston, Kent BR2 6HJ, U.K Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1972) 130 (1): 25P. https://doi.org/10.1042/bj1300025P Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Cite Icon Cite Get Permissions Citation J Coombs, C W Baldry, C Bucke; Metabolic regulation in the C4 dicarboxylic acid pathway of photosynthesis. Biochem J 1 November 1972; 130 (1): 25P. doi: https://doi.org/10.1042/bj1300025P Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1972 The Biochemical Society1972 Article PDF first page preview Close Modal You do not currently have access to this content.

Chloroplast peripheral reticulum in Nymphoides indica

Summary An extensive chloroplast reticulum is present in the lower epidermis and sub-epidermis of the leaf of Nymphoides indica . It causes distortion of the chloroplast margin, and may appear in the form of vesicles or a complex tubular network. Previous reports of chloroplast peripheral reticulum have suggested a relationship with the C 4 -dicarboxylic acid pathway of photosynthesis. N. indica has the recognised characteristics of a C 3 plant.

Studies on the mechanism of activation and inactivation of pyruvate, phosphate dikinase. A possible regulatory role for the enzyme in the C4 dicarboxylic acid pathway of photosynthesis.

1. The activity of pyruvate,P(i) dikinase in leaves of maize and Amaranthus palmeri rapidly falls on transferring illuminated plants to darkness. Illumination of dark-treated plants results in an immediate rapid increase in activity of the enzyme, the final activity reached being dependent on the intensity of the incident light. 2. Activation of the enzyme in extracts of dark-treated maize leaves after gel filtration on Sephadex G-25 requires a thiol and P(i). The P(i) requirement for activation can be replaced by arsenate. Activation of the enzyme is inhibited by AMP and GMP and possibly also by ADP and ATP. Activation of the enzyme after gel filtration on Sephadex G-200 also requires a heat-labile component that is excluded by Sephadex G-25. 3. The active enzyme isolated from illuminated leaves is inactivated by ADP in the presence of a thiol, the rate of inactivation being very much faster in air than in an oxygen-free atmosphere. Reactivation of the ADP-inactivated enzyme requires a thiol, P(i) and a component excluded by Sephadex G-25 but considerably retarded by Sephadex G-200. 4. The active enzyme is rapidly and irreversibly inactivated in the absence of a thiol. Inactivation is accelerated by both sodium diethyldithiocarbamate and tetraethylthiuram disulphide, and the enzyme inactivated by these reagents is completely reactivated by incubation with dithiothreitol. This reactivation does not require P(i). The inactive enzyme from dark-treated leaves is stabilized by diethyldithiocarbamate and can be partially activated by dithiothreitol alone; complete reactivation requires both dithiothreitol and P(i). 5. The enzyme activity is markedly inhibited by the thiol reagents p-chloromercuribenzoate, gamma-(p-arsenophenyl)-n-butyrate and an equimolar mixture of arsenite and 2,3-dimercaptopropan-1-ol. 6. The processes of activation and inactivation observed in vitro are discussed in relation to the regulation of pyruvate,P(i) dikinase activity in the leaf.

A new enzyme for the interconversion of pyruvate and phosphopyruvate and its role in the C4 dicarboxylic acid pathway of photosynthesis.

1. An enzyme was isolated from leaves of tropical grasses that catalyses the reversible conversion of pyruvate, ATP and orthophosphate into phosphopyruvate, AMP and pyrophosphate. A requirement for Mg(2+) could not be replaced by Mn(2+) or Ca(2+). 2. By replacing orthophosphate with [(32)P]orthophosphate or with arsenate, evidence was provided that the orthophosphate consumed appears in pyrophosphate. 3. Without Mg(2+) or 2-mercaptoethanol the enzyme was rapidly and irreversibly inactivated. EDTA only partially replaced the requirement for the thiol compound. The enzyme was considerably more unstable at 0 degrees or when frozen than at 22 degrees . Even with the best conditions devised the enzyme lost about 25% of its activity every 3hr. 4. The activities of the enzyme in leaves of the tropical grasses sugar cane (Saccharum hybrid var. Pindar), maize (Zea mays) and sorghum (Sorghum vulgare) were comparable with their maximum photosynthesis rates. The enzyme was not detectable in leaf extracts from several other plants. 5. Its role in photosynthesis is discussed.