Dark CO2 Fixation Research Articles

Einfluß von NaCl und blattalter auf die CO2-dunkelfixierung bei halophyten — Vergleichende untersuchung bei Mesembryanthemum crystallinum und Atriplex spongiosa

Summary Species used in this investigation were Atriplex spongiosa and Mesembryanthemum crystallinum. Mesembryanthemum-plants having 3 successive leaf pairs (numbered with ascending insertion) were treated with 150 and 300 mM NaCl-solutions, respectively, while Atriplex-plants having 7 successive leaves and branches originated in the axils of the leaves were only treated with 300 mM NaCl. During the following 20–30 days the increase of NaCl in the leaves and the incorporation of 14CO2 in the dark was determined. The experiment showed that the middle leaves, before they had reached their approximate final size, had the highest rates of 14CO2-incorporation in the dark. In the course of the experiment the, optimal CO2 dark fixation rate shifted towards the tip of the plants. This was the case in treated and untreated Mesembryanthemum-plants and in untreated Atriplex plants. Leaves of treated Atriplex plants wilted and were killed within 20 days of NaCl-treatment. In contrast, leaves of the branches were not affected by NaCl. During the first days of NaCl-treatment 14CO2 fixation declined. The lower CO2 incorporation of the branches of Atriplex was not restored as was the case in Mesembryanthemum-leaves. Here the fixation rate of the treated plants reached the level of the untreated ones within 13 days. Thereafter a drastic increase in 14CO2 dark fixation occurred. At that time plants exhibit a Crassulacean acid metabolism, as was reported earlier. The lag phase between the beginning of the NaCl treatment and the first appearence of increased dark fixation is not affected by the concentration of NaCl in the growing solution. But leaf age and NaCl-concentration influence the magnitude of dark fixation. The flexibility and possibility of adaptation to changed environment conditions decreases with increasing leaf age. The first leaf pair of Mesembryanthemum was killed by NaCl, the increase in dark fixation of the second leaf pair was half of that exhibited by the third leaf pair. The results are discussed on a morphogenetic and oecophysiological basis.

Carbon dioxide fixation by epidermal and mesophyll tissues of Tulipa and Commelina

Rates of (14)CO2 fixation by epidermal tissue of Tulipa gesneriana (tulip) and Commelina diffusa are only slightly higher in the light than in the dark while in mesophyl tissues rates are much greater in the light. The first products of (14)CO2 fixation by epidermal tissue of Tulipa gesneriana and C. diffusa in the light and dark are malate and aspartate. In addition to these dominating dicarboxylic acids, 3-phosphoglyceric acid and sugar phosphates appear in the light, while in the dark only the amino acids, glutamate and glutamine become labelled. Mesophyll tissue of tulip and C. diffusa, however, gives typical CO2 fixation patterns of the labelled products of C3 plants. Furthermore, a period of dark (14)CO2 fixation followed by a light (12)CO2 chase carried out with epidermal tissue suggested that malate can act has the precursor of phosphorylated compounds of the Calvin cycle and consequently of starch. The data are consistent with the view that guard cells are able to exhibit Crassulacean acid metabolism.

The effect of oxygen concentration during preillumination on enhanced dark CO2-fixation by maize leaves

Summary The effect of oxygen concentration: 0%, 21%, and 100% during the period of preillumination in CO2-free atmosphere on 2 minutes enhanced dark 14CO2-fixation and on its products was investigated. It has been found that enhanced dark 14CO2-fixation depends on oxygen concentration. The pattern of labelled products was unaffected by the atmospheric conditions during the period of preillumination. About 76% of the incorporated radioactivity was located in malate and aspartate. For comparison purposes the radioactivity of the products of 2 minutes photosynthesis and ordinary dark 14CO2-fixation were also examined.

Salt Responses of Carboxylation Enzymes from Species Differing in Salt Tolerance

This paper reports effects of salts on in vitro activity of phosphoenolpyruvate carboxylase and ribulose-1,5-diphosphate carboxylase, isolated from species differing in salt tolerance.Inhibition of phosphoenolpyruvate carboxylase by the inorganic salts KCl, NaCl, and Na(4)SO(4) depended on the source of the enzyme. Phosphoenolpyruvate carboxylase isolated from leaves of C(4) plants was extremely sensitive to inorganic salts, whereas the enzyme extracted from roots of C(4) plants or from both shoots and roots of C(3) plants was much less sensitive. Ribulose-1,5-diphosphate carboxylase was less salt-sensitive than the phosphoenolpyruvate carboxylases. Differences in salt sensitivity of carboxylases were observed over a wide pH range. The results suggest substantial physical-chemical differences between phosphoenolpyruvate carboxylases functioning in photosynthesis and in CO(2) dark fixation.Among C(4) species, phosphoenolpyruvate carboxylase from halophytic species was more salt-sensitive than that from a salt-sensitive species. This anomaly, between in vitro response of enzymes and growth response of the plants, is briefly discussed.

THE PHYSIOLOGICAL STATE WITH RESPECT TO NITROGEN OF PHYTOPLANKTON FROM LOW‐NUTRIENT SUBTROPICAL WATER AS MEASURED BY THE EFFECT OF AMMONIUM ION ON DARK CARBON DIOXIDE FIXATION1

The ammonium ion enhancement method has been used to estimate the state of nitrogen nutrition in natural populations of marine organisms, with the advantage that the native population can be assessed at time zero. The ammonium ion does not stimulate dark CO2 fixation by natural populations of phytoplankton in the low nitrogen subtropical waters of the Florida Strait, indicating that the cells are not physiologically nitrogen deficient; however nitrogen may still be limiting population size.When enhancement was not noted at time zero, incubation of the water in a carboy resulted in depletion of the available nitrogen and a physiological state of nitrogen deficiency subsequently became measurable by this method. The eventual positive results from the test therefore confirm the negative results at time zero.

The development of photosynthesis in dark-grown barley leaves upon illumination

Dark-grown barley leaves (Hordeum vulgare L.) were exposed to varying periods of illumination, followed by the supply of 14CO2 for 14 min in light or in darkness. Alcoholic extracts of the leaves were analyzed by chromatography. It was found that leaves without previous illumination were able to synthesize only malate, aspartate, glutamate, citrate, and succinate, equally in light or darkness. The products of dark fixation of 14CO2 were not affected by the length of prior illumination. In light, after 2 to 4 h of illumination, the synthesis of malate, aspartate, and glutamate was greatly accelerated. At this time intermediates of the Calvin cycle began to appear, followed by a rapid increase in sucrose synthesis. After more than 6 h of illumination, sucrose became the main photosynthetic product. A kinetic examination of the carbon flow into intermediates of carboxylation in light and in darkness was also conducted.The results indicate that during chloroplast development upon illumination there is a successive activation of distinct components of photosynthesis. The first photosynthetic reaction is a light-dependent β-carboxylation. This is followed by the development of the Calvin cycle, and the glycolate pathway. Dark CO2 fixation appears to be a different process from light-requiring β-carboxylation, located in a separate part of the cell.

Comparative Rates of Dark CO2Uptake and Acidification in the Bromeliaceae, Orchidaceae, and Euphorbiaceae

Dark CO2 uptake, titratable acid, pH changes, percentage dry weight, and leaf thickness were compared in 30 genera of angiosperms belonging to the Bromeliaceae, Orchidaceae, and Euphorbiaceae. In each family, the more primitive taxa did not exhibit dark CO2 uptake and dark acidification while the more specialized taxa generally exhibited this system. There appears to be a correlation between the physiological characters studied and the broad phylogeny of the families studied. It is suggested that there has been a concomitant development of dark CO2 fixation with a decreased transpiration ratio and that these have been factors in the successful adaptive radiation of these three families into more xeric environments. There was a significant correlation between dark CO2 exchange and dark acidification and between dark CO2 exchange and leaf thickness in all three families. Crassulacean acid metabolism appears to be associated with a complex of xeromorphic characters rather than strictly with succulence.

Light-enhanced carbon dioxide fixation in isolated chloroplasts

Preillumination of leaves of spinach, soybean and maize in the absence of CO2 greatly enhanced the capacity for fixing CO2 in an immediately following dark period. Lightenhanced dark CO2-fixation was further observed in isolated chloroplasts of spinach and soybean. When isolated chloroplasts were illuminated, CO2-fixing capacity in the subsequent dark period increased rapidly at first and later more slowly attaining a stationary value in about 20 min. When the light was turned off at this stage, the capacity decreased very rapidly becoming zero in about 10 min. The magnitude of the enhanced dark fixation and its decay in the dark were not influenced by the presence or absence of atmospheric oxygen. In both leaves and isolated chloroplasts, no significant change in oxygen (21%) occurred in distribution patterns of radioactivity in products fixed by photosynthetic, or light-enhanced, dark, 14CO2-fixation. In preilluminated leaves 14C was incorporated into sucrose in the subsequent dark period, indicating that the photosynthetic carbon reduction cycle is operating in light-enhanced dark fixation in higher plants.

Effects of Mild Water Stress on Enzymes of Nitrate Assimilation and of the Carboxylative Phase of Photosynthesis in Barley1

The effects of water stress were determined on enzymes of nitrate assimilation, of the carboxylative phase of photosynthesis, and of dark CO2 fixation in the first leaves of Hordeum vulgare L. After water removal, decreased activity of nitrate reductase was detected at the same time that water potential decreased in the first leaves and growth of the second leaves ceased. Up to 58% of the nitrate reductase activity was lost during the 4‐day stress period. Nitrite reductase activity showed a tendency to decrease. Phosphoenolpyruvate carboxylase activity decreased 1 day later in the stress period and by only half as much as did nitrate reductase activity. Twenty‐four hours after rewatering, the activities of nitrate reductase and phosphoenolpyruvate carboxylase had recovered completely. This recovery occurred during the same time that water potential increased in the first leaves and elongation of the second leaf began.Activities of phosphoribulokinase and ribulose‐l,5‐diP carboxylase were affected little by water stress. The reported rapid decrease in photosynthetic fixation of CO2 at the onset of water stress may be due less to changes in these enzyme levels than to restrictions in gaseous exchange by reduction of stomatal aperture. Concentrations of chlorophyll, soluble protein, and nitrate were slightly lower in the first leaves of water‐stressed plants.The reduction in the activities of phosphoenolpyruvate carboxylase and, especially, nitrate reductase could be part of a biochemical adaptation to stress conditions, causing a decrease in synthetic capabilities so as to reduce overall energy requirements.

Effects of preillumination with light of different wavelengths on subsequent dark CO2-fixation in Chlorella cells

The effects of preillumination with monochromatic red or blue light on the subsequent dark 14CO2-fixation in Chlorella cells were studied under aerobic as well as anaerobic conditions. When the cell suspension was made aerobic by bubbling air (CO2-free) throughout the periods of preillumination and the following dark 14CO2-fixation, the initial fixation product was mainly PGA. The radioactive carbon first incorporated in PGA was transferred mostly to aspartate during the later periods of dark 14CO2-fixation. The rate of 14C-incorporation into aspartate after preillumination with blue light was 2 to 3 times as high as that observed after red-light pretreatment. The observations support our previous inference that the activity of PEP carboxylase in Chlorella cells is stimulated by preillumination with blue light. When nitrogen gas was used during preillumination and the subsequent dark fixation, the radioactivity of 14C incorporated during the initial enhanced 14CO2-fixation was eventually transferred to alanine and lactate. The increase in radioactivity of alanine and lactate was more pronounced during dark fixation after preillumination with red light than after preillumination with blue light.

Dark Fixation of CO2 in the Lake with Special Reference to Organic Matter Production

Dark Fixation of CO2 in the Lake with Special Reference to Organic Matter Production

PARTIAL IDENTIFICATION OF DARK 14CO2 FIXATION PRODUCTS IN LEAVES OF CATTLEYA (ORCHIDACEAE)

SummaryFollowing exposure of Cattleya leaves to 14CO2 in the dark, labelled malate, citrate and an unidentified compound were detected by thin layer chromatography. This is interpreted to suggest the existence in Cattleya leaves of a dark CO2 fixation pathway which may be similar to that found in other plants which can fix large amounts of carbon in the dark.

Non-Autotrophic Carbon Dioxide Metabolism in Cacti

Non-autotrophic ("dark") 14CO2 metabolism and associated acid accumulation were studied in the Cactaceae. Carbon dioxide assimilation and oxygen uptake were generally lower than in crassulacean succulents. The primary products were organic acids (malic acid) and amino acids. Little or no 14C activity was detected in lipoidal or neutral components. After a 2-hr dark CO2 fixation period, the first-order rate constant for steady-state decarboxylation in the dark was 1.7 x 10-3 min-1 and in the light was 0.2 x 10-3 min-1. The greater rate in the dark was reflected in the decay of the primary product, malic acid. The slower rate in the light was accounted for by photosynthetic reassimilation of 14CO2. In part, the observed diurnal fluctuation of organic acids may be explained in terms of steady-state decarboxylation. In the dark carboxylation evidently exceeds decarboxylation, and organic acids accumulate. In the light much of the available CO2 would be assimilated by photosynthetic carboxylation reactions so that non-autotrophic carboxylation may be less than steady-state decarboxylation. Thus, a diurnal fluctuation of organic acids would result.

Fissazione di C14O2in Colture di Tessuti Vegetali « in Vitro »

Abstract C14O2 fixation in plant tissues « in vitro ». — In the present work it has been examinated the autotrophic and heterotrophic CO2 fixation of explants of « Helianthus tuberosus » « in vitro » and the photosyntetic efficiency of leaves produced from buds of « in vitro » explants of « Cichorium intybus » compared with that of mature leaves from normal plants of the same species. From our results it is evident that « in vitro » explants of « Helianthus tuberosus », grown, in the light, are able to autotrophically incorporate C14O2; the distribution of the radioactivity into the various fractions shows a large influence of the light on the neutral fraction containing sugars (50% of the total radioactivity). In the chlorophyllous explants the dark CO2 fixation is obviously of heterotrophic type: 97% of the total radioactivity is incorporated in amine acids (43%) and the organic acids (53%); on the other hand in the dark grown explants the radioactivity is differently distributed between amino acids (59...

LEAF RESISTANCE TO WATER VAPOR TRANSFER IN SUCCULENT PLANTS: EFFECT OF THERMOPERIOD

Leaf resistance (RL) of Kalanchoe blossfeldiana to water vapor transfer was determined with a resistance hygrometer. The diurnal leaf‐resistance change followed a normal pattern (i.e., low in light and higher in dark) when plants were pretreated with cool thermoperiods or with thermoperiods having little diurnal temperature fluctuation. Large diurnal temperature fluctuations (30‐18, 26‐15 C) resulted in apparent nocturnal stomatal opening. Nocturnal stomatal opening was more apparent than real since leaf‐resistance measurements indicated day stomatal closing rather than complete night opening. Low nocturnal leaf resistances ( < 10 sec/cm) were not measured in the dark; however, resistances tended to decrease toward the end of the dark period indicating some degree of nocturnal stomatal opening. Leaf resistances were generally higher than those reported for nonsucculent plants. The data suggested that gaseous diffusion (Q) into or out of the leaves of K. blossfeldiana would be adequately described by an equation of the form, Q = D Δ e RL−1. There was little or no indication that physiological long days (15 min of 660 mμ light in the middle of a 16‐hr dark period), which prevented flowering and reduced organic acid accumulation, significantly affected leaf resistance. It was concluded that the photoperiod response effects of dark CO2 fixation were probably not due to leaf‐resistance changes and, therefore, not due to stomatal aperture changes.

Leaf Resistance to Water Vapor Transfer in Succulent Plants: Effect of Thermoperiod

Leaf resistance (RL) of Kalanchoe blossfeldiana to water vapor transfer was determined with a resistance hygrometer. The diurnal leaf-resistance change followed a normal pattern (i.e., low in light and higher in dark) when plants were pretreated with cool thermoperiods or with thermoperiods having little diurnal temperature fluctuation. Large diurnal temperature fluctuations (30-18, 26-15 C) resulted in apparent nocturnal stomatal opening. Nocturnal stomatal opening was more apparent than real since leaf-resistance measurements indicated day stomatal closing rather than complete night opening. Low nocturnal leaf resistances ( < 10 sec/cm) were not measured in the dark; however, resistances tended to decrease toward the end of the dark period indicating some degree of nocturnal stomatal opening. Leaf resistances were generally higher than those reported for nonsucculent plants. The data suggested that gaseous diffusion (Q) into or out of the leaves of K. blossfeldiana would be adequately described by an equation of the form, Q = D Δ e RL−1. There was little or no indication that physiological long days (15 min of 660 mμ light in the middle of a 16-hr dark period), which prevented flowering and reduced organic acid accumulation, significantly affected leaf resistance. It was concluded that the photoperiod response effects of dark CO2 fixation were probably not due to leaf-resistance changes and, therefore, not due to stomatal aperture changes.

Vergleichende Untersuchungen zur Photosynthese und Atmung der Blätter von Schwefelmangelpflanzen

In the course of our investigations on sulfur metabolism in higher plants possible changes of photosynthesis and respiration induced by sulfur deficiency have been studied. Leaves of S-deficient and normal tomato plants were illuminated in the presence of 14CO2 for various times. After subsequent lyophilization, chloroplasts were isolated using a non-aqueous procedure which prevents leaching of hydrophilic substances out of the plastids. The time course of distribution of phosphoglycerate, sugar mono- and -diphosphates, and of malate between chloroplasts and the cytoplasm was calculated from the 14C-incorporation into the fractions obtained. Neither a significant difference in the 14C-fixation rate nor remarkable changes of sites of synthesis and of transport of photosynthetic products between chloroplasts and cytoplasm could be observed between normal and S-deficient leaves. However, in S-deficient leaves the percentage of the sugar monophosphates is higher than normal even after 7 min photosynthesis, the 14C-activity in starch is twice as high as in normal leaves, whereas sucrose was labelled only weakly. The respiration rate measured manometrically, is on a unit leaf area basis, similar to that of normal leaves; protein is not useful as a reference figure owing to the reduced protein content of the deficient leaves. Infiltration of discs of leaves with 14C-sucrose and subsequent measurement of the various 14C-labelled metabolites resulted in a strongly reduced labelling of citrate, malate, aspartate, and glutamate as compared with normal leave cells. Alanine was found to be more radioactive. Since in addition citrate was less radioactive after 4 min dark fixation of 14CO2 we suggest from our results that the citrate cycle may be inhibited directly or indirectly by S-deficiency and that direct oxidation may dominate in the degradation of glucose in the S-deficient leaf cell.

RELATIONSHIPS AMONG CO2 DARK-FIXATION, SUCCULENCE, FLOWERING, AND ORGANIC ACID FORMATION IN KALANCHOE BLOSSFELDIANA VARIETY TOM THUMB

Kalanchoe blossfeldiana variety Tom Thumb was treated photoperiodically in regular and CO2-free air and examined at two widely separated time intervals for interrelationships among flowering, succulence, capacity for CO2 dark-fixation, and organic acid formation. These processes and leaf thickening are all under photoperiodic control and increase with increasing numbers of short-day treatments. They also occur in a CO2-free atmosphere on 9-hour photoperiods although CO2 dark-fixation and organic acid formation are limited to the low level of the long-day treated plants at 5 weeks' time. Only CO2 dark-fixation and organic acid formation appear to be interrelated and apparently utilize respiratory CO2 if treated in a CO2-free atmosphere. This capacity to use respiratory CO2 increases with maturity of the plants. Flowering does not control the development of succulence, organic acid formation, or the capacity for CO2 dark-fixation. Likewise, capacity for dark-fixation and organic acid formation do not control flowering and can occur in vegetative Tom Thumb plants that do not exhibit appreciable succulence.

Cell-free Hydrogenase from Chlamydomonas

10. LATIES, G. G. 1959. The development and control of coexisting respiratory systems in slices of chicory root. Archiv. Biochem. Biophys. 79: 378-91. 11. LATIES, G. G. 1962. Controlling influence of thickness on development and type of respiratory activity in potato slices. Plant Physiol. 37: 679-90. 12. MAcDONALD, I. R. AND P. C. DEKOCK. 1958. Temperature control and metabolic drifts in aging disks of storage tissue. Ann. Botany NS 22: 429-48. 13. MAcDONALD, I. R., P. C. DEKOCK, AND A. H. KNIGHT. 1960. Variations in the mineral content of storage tissue disks maintained in tap water. Physiol. Plantarum 13: 77-89. 14. SPLITTSTOESSER, W. E. 1963. Some aspects of dark CO2 fixation in storage tissues. Ph.D. thesis. Purdue University, Lafayette, Indiana. 15. ULRICH, A. 1941. Metabolism of non-volatile organic acids in excised barley roots as related to cation-anion balance during salt accumulation. Am. J. Botany. 28: 526-37. 16. WOLF, B. AND V. ICHESAKA. 1947. Rapid chemical soil and plant tests. Soil Sci. 64: 227-44.

A Comparative Study of the Influence of Salt Type and Concentration on14CO2Fixation in Potato Slices at 25° C and 0° C

Dark fixation of 14CO2 was followed in potato disks under varying salt treatments at 0° C and 25° C. It is shown that the specific activity of the 14CO2 supplied is heavily diluted by endogenously produced CO2 and that the apparently greater fixation of 14CO2, at 0° C as compared with that at 25 ° C is due to the lower respiration rate at 0° C, with consequently less dilution of the 14CO2. supplied. At 25° C organic acid formation in response to different salt treatments fulfils the common expectation, 14CO2 fixation increasing in the presence of K2SO4 and decreasing in CaCl2 relative to that in KCl. The role of organic acids in maintaining ionic balance within the cell at 25° C is thereby indicated but at 0° C organic acid adjustments did not follow the normal pattern. At 25° C but not at o° C increasing external concentration of KCI resulted in an increased level of 14CO2 fixation.