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1.
Comparative ecophysiology of C3 and C4 plants 总被引:2,自引:3,他引:2
Abstract. In this review we relate the physiological significance of C4 photosynthesis to plant performance in nature. We begin with an examination of the physiological consequences of the C4 pathway on photosynthesis, then discuss the ecophysiological performance of C4 plants in contrasting environments. We then compare the performance of C3 and C4 plants when they occur together in similar habitats, and finally discuss the distribution of C4 photosynthesis with respect to the physical environment, phylogeny, and life form. 相似文献
2.
C4 photosynthesis in a single C3 cell is theoretically inefficient but may ameliorate internal CO2 diffusion limitations of C3 leaves 总被引:2,自引:1,他引:1
S. VON CAEMMERER 《Plant, cell & environment》2003,26(8):1191-1197
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. 相似文献
3.
The widely used steady‐state model of Farquhar et al. (Planta 149: 78–90, 1980) for C3 photosynthesis was developed on the basis of linear whole‐chain (non‐cyclic) electron transport. In this model, calculation of the RuBP‐regeneration limited CO2‐assimilation rate depends on whether it is insufficient ATP or NADPH that causes electron transport limitation. A new, generalized equation that allows co‐limitation of NADPH and ATP on electron transport is presented herein. The model is based on the assumption that other thylakoid pathways (the Q‐cycle, cyclic photophosphorylation, and pseudocyclic electron transport) interplay with the linear chain to co‐contribute to a balanced production of NADPH and ATP as required by stromal metabolism. The original model assuming linear electron transport limited either by NADPH or by ATP, predicts quantum yields for CO2 uptake that represent the highest and the lowest values, respectively, of the range given by the new equation. The applicability of the new equation is illustrated for a number of C3 crop species, by curve fitting to gas exchange data in the literature. In comparison with the original model, the new model enables analysis of photosynthetic regulation via the electron transport pathways in response to environmental stresses. 相似文献
4.
O. Ghannoum K. Siebke S. Von Caemmerer & J. P. Conroy 《Plant, cell & environment》1998,21(11):1123-1131
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. 相似文献
5.
IRON REQUIREMENTS OF C3 AND C4 PLANTS 总被引:1,自引:1,他引:0
6.
Low-temperature photosynthetic performance of a C4 grass and a co-occurring C3 grass native to high latitudes 总被引:1,自引:1,他引:0
The photosynthetic performance of C4 plants is generally inferior to that of C3 species at low temperatures, but the reasons for this are unclear. The present study investigated the hypothesis that the capacity of Rubisco, which largely reflects Rubisco content, limits C4 photosynthesis at suboptimal temperatures. Photosynthetic gas exchange, chlorophyll a fluorescence, and the in vitro activity of Rubisco between 5 and 35 °C were measured to examine the nature of the low‐temperature photosynthetic performance of the co‐occurring high latitude grasses, Muhlenbergia glomerata (C4) and Calamogrostis canadensis (C3). Plants were grown under cool (14/10 °C) and warm (26/22 °C) temperature regimes to examine whether acclimation to cool temperature alters patterns of photosynthetic limitation. Low‐temperature acclimation reduced photosynthetic rates in both species. The catalytic site concentration of Rubisco was approximately 5.0 and 20 µmol m?2 in M. glomerata and C. canadensis, respectively, regardless of growth temperature. In both species, in vivo electron transport rates below the thermal optimum exceeded what was necessary to support photosynthesis. In warm‐grown C. canadensis, the photosynthesis rate below 15 °C was unaffected by a 90% reduction in O2 content, indicating photosynthetic capacity was limited by the capacity of Pi‐regeneration. By contrast, the rate of photosynthesis in C. canadensis plants grown at the cooler temperatures was stimulated 20–30% by O2 reduction, indicating the Pi‐regeneration limitation was removed during low‐temperature acclimation. In M. glomerata, in vitro Rubisco activity and gross CO2 assimilation rate were equivalent below 25 °C, indicating that the capacity of the enzyme is a major rate limiting step during C4 photosynthesis at cool temperatures. 相似文献
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8.
Leaves of twelve C3 species and six C4 species were examined to understand better the relationship between mesophyll cell properties and the generally high photosynthetic rates of these plants. The CO2 diffusion conductance expressed per unit mesophyll cell surface area (gCO2cell) cell was determined using measurements of the net rate of CO2 uptake, water vapor conductance, and the ratio of mesophyll cell surface area to leaf surface area (Ames/A). Ames/A averaged 31 for the C3 species and 16 for the C4 species. For the C3 species gCO2cell ranged from 0.12 to 0.32 mm s-1, and for the C4 species it ranged from 0.55 to 1.5 mm s-1, exceeding a previously predicted maximum of 0.5 mm s-1. Although the C3 species Cammissonia claviformis did not have the highest gCO2cell, the combination of the highest Ames and highest stomatal conductance resulted in this species having the greatest maximum rate of CO2 uptake in low oxygen, 93 μmol m-2 s-1 (147 mg dm-2 h-1). The high gCO2cell of the C4 species Amaranthus retroflexus (1.5 mm s-1) was in part attributable to its thin cell wall (72 nm thick). 相似文献
9.
Abstract Evidence is drawn from previous studies to argue that C3—C4 intermediate plants are evolutionary intermediates, evolving from fully-expressed C3 plants towards fully-expressed C4 plants. On the basis of this conclusion, C3—C4 intermediates are examined to elucidate possible patterns that have been followed during the evolution of C4 photosynthesis. An hypothesis is proposed that the initial step in C4-evolution was the development of bundle-sheath metabolism that reduced apparent photorespiration by an efficient recycling of CO2 using RuBP carboxylase. The CO2-recycling mechanism appears to involve the differential compartmentation of glycine decarboxylase between mesophyll and bundle-sheath cells, such that most of the activity is in the bundlesheath cells. Subsequently, elevated phosphoenolpyruvate (PEP) carboxylase activities are proposed to have evolved as a means of enhancing the recycling of photorespired CO2. As the activity of PEP carboxylase increased to higher values, other enzymes in the C4-pathway are proposed to have increased in activity to facilitate the processing of the products of C4-assimilation and provide PEP substrate to PEP carboxylase with greater efficiency. Initially, such a ‘C4-cycle’ would not have been differentially compartmentalized between mesophyll and bundlesheath cells as is typical of fully-expressed C4 plants. Such metabolism would have limited benefit in terms of concentrating CO2 at RuBP carboxylase and, therefore, also be of little benefit for improving water- and nitrogen-use efficiencies. However, the development of such a limited C4-cycle would have represented a preadaptation capable of evolving into the leaf biochemistry typical of fully-expressed C4 plants. Thus, during the initial stages of C4-evolution it is proposed that improvements in photorespiratory CO2-loss and their influence on increasing the rate of net CO2 assimilation per unit leaf area represented the evolutionary ‘driving-force’. Improved resourceuse efficiency resulting from an efficient CO2-concentrating mechanism is proposed as the driving force during the later stages. 相似文献
10.
Models of carbon metabolism in C3 -C4 intermediate plants as applied to the evolution of C4 photosynthesis 总被引:4,自引:4,他引:0
M. PEISKER 《Plant, cell & environment》1986,9(8):627-635
Abstract Models developed to explain the biphasic response of CO2 compensation concentration to O2 concentration and the C3-like carbon isotope discrimination in C3-C4 intermediate species are used to characterize quantitatively the steps necessary in the evolution of C4 photosynthesis. The evolutionary stages are indicated by model outputs, CO2 compensation concentration and δ13C value. The transition from intermediate plants to C4 plants requires the complete formation of C4 cycle capacity, expressed by the models as transition from C4 cycle limitation by phosphoenolpyruvate (PEP) regeneration rate to limitation by PEP carboxylase activity. Other steps refer to CO2 leakage from bundle sheath cells, to further augmentations of C4 cycle components, to the repression of ribulose-1,5-bisphos-phate carboxylase in the mesophyll cells, and to a decrease in the CO2 affinity of the enzyme. Possibilities of extending the suggested approach to other physiological characteristics, and the adaptive significance of the steps envisaged, are discussed. 相似文献
11.
Stomatal acclimation over a subambient to elevated CO2 gradient in a C3 /C4 grassland 总被引:2,自引:1,他引:1
H. Maherali C. D. Reid H. W. Polley H. B. Johnson & R. B. Jackson 《Plant, cell & environment》2002,25(4):557-566
An investigation to determine whether stomatal acclimation to [CO2] occurred in C3/C4 grassland plants grown across a range of [CO2] (200–550 µmol mol?1) in the field was carried out. Acclimation was assessed by measuring the response of stomatal conductance (gs) to a range of intercellular CO2 (a gs–Ci curve) at each growth [CO2] in the third and fourth growing seasons of the treatment. The gs–Ci response curves for Solanum dimidiatum (C3 perennial forb) differed significantly across [CO2] treatments, suggesting that stomatal acclimation had occurred. Evidence of non–linear stomatal acclimation to [CO2] in this species was also found as maximum gs (gsmax; gs measured at the lowest Ci) increased with decreasing growth [CO2] only below 400 µmol mol?1. The substantial increase in gs at subambient [CO2] for S. dimidiatum was weakly correlated with the maximum velocity of carboxylation (Vcmax; r2 = 0·27) and was not associated with CO2 saturated photosynthesis (Amax). The response of gs to Ci did not vary with growth [CO2] in Bromus japonicus (C3 annual grass) or Bothriochloa ischaemum (C4 perennial grass), suggesting that stomatal acclimation had not occurred in these species. Stomatal density, which increased with rising [CO2] in both C3 species, was not correlated with gs. Larger stomatal size at subambient [CO2], however, may be associated with stomatal acclimation in S. dimidiatum. Incorporating stomatal acclimation into modelling studies could improve the ability to predict changes in ecosystem water fluxes and water availability with rising CO2 and to understand their magnitudes relative to the past. 相似文献
12.
The evolution of C4 photosynthesis 总被引:8,自引:4,他引:4
Rowan F. Sage 《The New phytologist》2004,161(2):341-370
13.
Immediate export in leaves of C3‐C4 intermediates were compared with their C3 and C4 relatives within the Panicum and Flaveria genera. At 35 Pa CO2, photosynthesis and export were highest in C4 species in each genera. Within the Panicum, photosynthesis and export in ‘type I’ C3‐C4 intermediates were greater than those in C3 species. However, ‘type I’ C3‐C4 intermediates exported a similar proportion of newly fixed 14C as did C4 species. Within the Flaveria, ‘type II’ C3‐C4 intermediate species had the lowest export rather than the C3 species. At ambient CO2, immediate export was strongly correlated with photosynthesis. However, at 90 Pa CO2, when photosynthesis and immediate export increased in all C3 and C3‐C4 intermediate species, proportionally less C was exported in all photosynthetic types than that at ambient CO2. All species accumulated starch and sugars at both CO2 levels. There was no correlation between immediate export and the pattern of 14C‐labelling into sugars and starch among the photosynthetic types within each genus. However, during CO2 enrichment, C4Panicum species accumulated sugars above the level of sugars and starch normally made at ambient CO2, whereas the C4Flaveria species accumulated only additional starch. 相似文献
14.
Carbon: terrestrial C4 plants 总被引:1,自引:1,他引:0
The carbon isotope composition of terrestrial C4 plants depends on the primary carboxylation of phosphoenolpyruvate (PEP) and on the diffusion of CO2 to the carboxylation sites, but is also influenced by the final carboxylation of ribulose-1,5-bisphosphate (RuBP). Several models have been used for reproducing this complex situation. In the present review, a particular model is applied as a means to interpret the effects of environmental and genetically determined factors on carbon isotope discrimination during C4 photosynthesis. As a new feature, the model considers four types of limitation of the overall CO2 assimilation rate. Both carboxylation reactions are assumed to be limited by either maximum enzyme activity or maximum substrate regeneration rate. The model is applied to experimental data on the effects of CO2, irradiance and water stress on short-term discrimination by leaves of several C4 species measured simultaneously with CO2 gas exchange characteristics. In particular, different patterns of the influence of low irradiances on carbon isotope discrimination are interpreted as due to variations in that irradiance at which a transition from limitation by PEP regeneration rate and RuBP carboxylase activity to limitation by the regeneration rates of both substrates occurs. After discussing literature data on the effects of environmental conditions on carbon isotope discrimination by C4 plants seasonal and developmental changes in carbon isotope composition, studies on the systematic and geographic distribution of C4 plants, evolutionary and genetical aspects, and some ecological implications are reviewed. 相似文献
15.
Plasma membranes were isolated from green leaves of maize ( Zea mays ), spinach ( Spinacia oleracea ), Setaria viridis and wheat ( Triticum aestivum cv. Omase) by aqueous two-phase partitioning. Carbonic anhydrase activity was detected in these membranes. The activity was inhibited by specific inhibitors for carbonic anhydrase, acetazolamide and ethoxyzolamide. The carbonic anhydrase activity was markedly enhanced by the addition of Triton X-100 to the plasma membranes. The highest activity was obtained in the presence of 0.015% detergent. The activity was scarcely affected when the plasma membrane vesicles were treated with proteinase K, but largely inactivated by the protease after treating the membranes with Triton X-100. These results indicate that carbonic anhydrase faces the cytoplasmic side of the membrane since plasma membranes purified by aqueous two-phase partitioning are tightly sealed vesicles of right side-out orientation (apoplastic side-out). With leaves of C4 plants, 20 to 60% of the total carbonic anhydrase activity was found in the microsomal fraction. By contrast, only 1 to 3% of the activity was found in the microsomal fraction from leaves of C3 plants. Western blot analysis showed that a polypeptide in the spinach plasma membrane cross-reacted with an antiserum raised against spinach chloroplast carbonic anhydrase, and that the molecular mass of the plasma membrane enzyme was higher than that of the chloroplast carbonic anhydrase (28 and 26 kDa, respectively). This indicates the presence of different molecular species of carbonic anhydrase in the chloroplast and the plasma membrane. 相似文献
16.
Carbon isotope discrimination in C3 -C4 intermediates 总被引:1,自引:1,他引:0
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. 相似文献
17.
The specific activity of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco, EC 4.1.1.39) was measured from the crude extracts of five C3 plants consisting of wheat ( Triticum aestivum L. cv. Maris Mink), spinach ( Spinacia oleracea L.), pea ( Pisum sativum L. cv. Greenfeast), pumpkin ( Cucurbita pepo L. cv. Jättiläismeloni) and Ceratodon purpureus (Hedw.) Brid., and two C4 plants, maize ( Zea mays L. ETA F1 ) and sugar sorghum [ Sorghum saccharatum (L. emend, L.) Moench]. The amount of Rubisco in the crude extracts was estimated by polyacrylamide gel electro-phoresis with the Coomassie Brilliant Blue staining procedure. The amounts of the dye bound to the purified Rubisco of different higher plants were similar. The method gave a linear response for both purified enzyme and crude extracts, and the results agreed with those observed by immunochemical methods. The addition of positive effectors such as inorganic phosphate was necessary to obtain maximal activity in the crude extracts of all the studied plants except in that of maize. No significant differences in the specific carboxylase activity at 25°C were found between the C3 and C4 plants. 相似文献
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19.
It has been suggested previously that Japanese larch ( Larix kaempferi ) exhibits characteristics of C4 photosynthesis. To further evaluate this suggestion, stable carbon isotope ratios were determined for leaf and bark tissue of Larix gmelini, L. kaempferi, L. laricina, L. Iyallii, L. occidentalis , and L. sibirica. All δ13 C values were more negative than –22‰. Short-term labeling with 14 CO2 showed that phosphoglyceric acid and other phosphorylated compounds were the first products of photosynthesis in L. sibirica. Both of these results strongly suggest that the initial fixation of atmospheric CO2 in these six Larix species is accomplished solely via the C3 photosynthetic pathway. 相似文献
20.
C4 plants are rare in the cool climates characteristic of high latitudes and altitudes, perhaps because of an enhanced susceptibility to photo‐inhibition at low temperatures relative to C3 species. In the present study we tested the hypothesis that low‐temperature photo‐inhibition is more detrimental to carbon gain in the C4 grass Muhlenbergia glomerata than the C3 species Calamogrostis Canadensis. These grasses occur together in boreal fens in northern Canada. Plants were grown under cool (14/10 °C day/night) and warm (26/22 °C) temperatures before measurement of the light responses of photosynthesis and chlorophyll fluorescence at different temperatures. Cool growth temperatures led to reduced rates of photosynthesis in M. glomerata at all measurement temperatures, but had a smaller effect on the C3 species. In both species the amount of xanthophyll cycle pigments increased when plants were grown at 14/10 °C, and in M. glomerata the xanthophyll epoxidation state was greatly reduced. The detrimental effect of low growth temperature on photosynthesis in M. glomerata was almost completely reversed by a 24‐h exposure to the warm‐temperature regime. These data indicate that reversible dynamic photo‐inhibition is a strategy by which C4 species may tolerate cool climates and overcome the Rubisco limitation that is prevalent at low temperatures in C4 plants. 相似文献