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1.
Hubick KT Hammer GL Farquhar GD Wade LJ von Caemmerer S Henderson SA 《Plant physiology》1990,92(2):534-537
Carbon-isotope discrimination (Δ) is used to distinguish between different photosynthetic pathways. It has also been shown that variation in Δ occurs among varieties of C3 species, but not as yet, in C4 species. We now report that Δ also varies among genotypes of sorghum (Sorghum bicolor Moench), a C4 species. The discrimination in leaves of field-grown plants of 12 diverse genotypes of sorghum was measured and compared with their grain yields. Discrimination varied significantly among genotypes, and there was a significant negative correlation between grain yield and Δ. The variation in Δ may be caused by genetic differences in either leakiness of the bundle-sheath cells or by differences in the ratio of assimilation rate to stomatal conductance. At the leaf level, the former should be related to light-use efficiency of carbon fixation and the latter should be related to transpiration efficiency. Both could relate to the yield of the crop. 相似文献
2.
大鵟的食性改变:来自稳定性碳同位素的证据 总被引:9,自引:0,他引:9
通过对大规模灭鼠后的海北高寒草甸生态系统大鵟、小型哺乳类以及雀形目鸟类肌肉稳定性碳同位素比值的测定发现,大篱的肌肉稳定性碳同位素比值介于-22.60‰和-23.10‰之间;小型哺乳类和主要雀形目鸟类肌肉稳定性碳同位素比值分别介于-25.57‰和-25.78‰以及-24.81‰和-22.51‰之间,且它们之间差异性显著。基于碳同位素的分馏模式(即动物和它食物之间稳定性碳同位素分馏在1‰~2‰之间),我们推断经大规模灭鼠后,大篱的食性发生了较大变化,其食物主要来源于高寒草甸的雀形目鸟类,而非原来的小型哺乳类。通过稳定性同位素营养级模型的运算发现,大蔫处在4.23左右的营养级;雀形目鸟类处在2.4到3.39左右的营养级,而小型哺乳类则处在1.45到1.82左右的营养级。进而采用稳定性同位素质量平衡模型计算得出,大篱的食物由35.04%的小型哺乳类和64.96%的雀形目鸟类所组成,进一步说明小型哺乳类在大量灭鼠后仅占大篱食物的很小一部分。由此可见,采取大规模的化学灭鼠,不仅降低了小型啮齿类天敌——大鵟的数量,而日使得其食谱发毕了巨大改变而转向草甸主要雀形目鸟类[动物学报49(6):764~768,2003]。 相似文献
3.
Short-term changes in leaf carbon isotope discrimination in salt- and water-stressed c(4) grasses 总被引:1,自引:5,他引:1
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Online carbon isotope discrimination (Δ) and leaf gas exchange measurements were made with control and salt-stressed Zea mays and Andropogon glomeratus, two NADP-ME type C4 grasses. Linear relationships between Δ and pi/pa (the ratio of intercellular to atmospheric CO2 partial pressure) were found for control plants which agreed well with theoretical models describing carbon isotope discrimination in C4 plants. These data provided estimates of , the proportion of CO2 fixed by phosphoenolpyruvate carboxylase which leaks out of the bundle sheath and the component of fractionation due to diffusion in air. Salt-stressed plants had wider variation in Δ for the same or less range in pi/pa. Additional work indicated Δ changed independently of pi/pa in both water- and salt-stressed plants, suggesting a possible diurnal change in as plant water status changed linked to a decrease in the activity of the C3 photosynthetic pathway relative to C4 pathway activity. The possible effect of stress-induced changes in on organic matter δ13 C of C4 plants is apt to be most apparent in chronically stressed environments. 相似文献
4.
Leaf carbon isotope ratios of plants from a subtropical monsoon forest 总被引:12,自引:0,他引:12
Summary Carbon isotope ratios were used to survey the distribution of photosynthetic pathways among taxa, the relationship between photosynthetic pathway and habitat light levels, and the relationship between intercellular CO2 levels of C3 plants and habitat light levels within a subtropical monsoon forest in southern China. Of 128 species, most (94) possessed the C3 photosynthetic pathway; 33 species possessed the C4 pathway and all of these were restricted to high light locations. There was one epiphytic CAM species. The C3 species were classified as occurring in open, intermediate, and closed canopy sites. Among C3 species, carbon isotope ratios tended to become more negative with decreasing light availability in the habitat.C.I.W.D.P.B. Pub no 931 相似文献
5.
Comparative studies of phosphoenolpyruvate carboxylase from c(3) and c(4) plants 总被引:2,自引:1,他引:2
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Phosphoenolpyruvate carboxylase (PEPC) from several C3 plants was compared to maize PEPC by immunoblotting using an antibody against maize PEPC and by peptide mapping. In C3 gramineous plants, PEPCs of slightly different monomeric sizes were detected as two bands for wheat and barley leaves, as three bands for etiolated maize leaves and as four bands for rice leaves by SDS-polyacrylamide gel electrophoresis and immunoblotting, whereas only one PEPC band was detected for maize leaves, a C4 plant, or tobacco leaves, a dicotyledonous C3 plant. The peptide fragment patterns of the lower molecular weight PEPC (major band in immunoblotting) in wheat leaves was similar to that of maize PEPC in peptide mapping by protein staining or by immunological detection, but the upper one (minor band) had a different pattern from the lower one in peptide mapping by immunological detection and few peptide fragments from this were recognized by the anti-(maize) PEPC antibody. These results suggest that there are multiple forms of PEPC subunits in the gramineous plants tested, and the major PEPC has a primary structure similar to that of maize PEPC. To obtain information about the expression of PEPCs in C3 plants, changes in the amount of PEPC protein were investigated during the greening of rice and wheat seedlings. Judging from the regulation by light, there were two types of PEPCs in greening rice seedlings, one induced by light and the other reduced by it. Greening wheat seedlings also show a PEPC band induced by light. These findings indicate that some PEPCs in C3 gramineous plants not only have structures similar to that of maize PEPC, but also are regulated by light in a similar manner. 相似文献
6.
Kinetic properties of phosphoenolpyruvate carboxylase from c(3), c(4), and c(3)-c(4) intermediate species of flaveria (asteraceae) 总被引:3,自引:3,他引:0
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Flaveria cronquistii (C3), F. chloraefolia (C3-C4), F. floridana (C3-C4), F. pubescens (C3-C4), F. anomala (C3-C4), F. linearis (C3-C4), F. brownii (C4), F. palmeri (C4), F. trinervia (C4) and F. australasica (C4), comprising 10 out of the 21 known species of the genus Flaveria (Asteraceae), were included in a comparative study of the kinetic and regulatory properties of green leaf phosphoenolpyruvate (PEP) carboxylase. At least three kinetically distinct enzyme-forms were identified on the basis of their affinities for PEP and the degree of allosterism with respect to this substrate. The kinetic properties of PEP carboxylase of most of the species seemingly were modified in vivo depending on the growth conditions of the plants. Km(PEPfree)-values of the enzyme from the five C3-C4 intermediate species ranged from 6 micromolar (F. chloraefolia, low light-grown) to 38 micromolar (F. pubescens, high light-grown). In contrast, the Km for PEP of PEP carboxylase from the C3 species F. cronquistii (13 micromolar) apparently was not influenced by growth conditions. The response of the enzyme from the C3 and C3-C4 species was hyperbolic in all cases. A second isoform with a lower affinity for PEP (88-100 micromolar), but also hyperbolic kinetics was found in the C4 species F. brownii, whereas in the three other C4 species examined a PEP carboxylase with a still lower affinity for PEP (187-221 micromolar) and sigmoidal kinetics was present. These isozyme-related kinetic data were supported by analyses of the elution behavior of the enzyme during anion-exchange chromatography on DEAE-Trisacryl M. The results are discussed with respect to the evolution of C4 photosynthesis in the Flaveria genus. 相似文献
7.
Summary Measurements of carbon isotope ratios of nine taxa of arid zone mosses from North America and 24 taxa of European bryophytes show consistent values indicative of C3 metabolism. Other morphological, physiological and biochemical characteristics provide the mechanism of adaptation to environmental stresses of heat and extended desiccation in these plants. Analyses of D content indicate that values become less negative with increasing aridity of the habitat. 相似文献
8.
Stomatal sensitivity to carbon dioxide and humidity: a comparison of two c(3) and two c(4) grass species 总被引:10,自引:3,他引:7
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The sensitivity of stomatal conductance to changes of CO2 concentration and leaf-air vapor pressure difference (VPD) was compared between two C3 and two C4 grass species. There was no evidence that stomata of the C4 species were more sensitive to CO2 than stomata of the C3 species. The sensitivity of stomatal conductance to CO2 change was linearly proportional to the magnitude of stomatal conductance, as determined by the VPD, the same slope fitting the data for all four species. Similarly, the sensitivity of stomatal conductance to VPD was linearly proportional to the magnitude of stomatal conductance. At small VPD, the ratio of intercellular to ambient CO2 concentration, Ci/Ca, was similar in all species (0.8-0.9) but declined with increasing VPD, so that, at large VPD, Ci/Ca was 0.7 and 0.5 (approximately) in C3 and C4 species, respectively. Transpiration efficiency (net CO2 assimilation rate/transpiration rate) was larger in the C4 species than in the C3 species at current atmospheric CO2 concentrations, but the relative increase due to high CO2 was larger in the C3 than in the C4 species. 相似文献
9.
Leaf anatomy of c(3)-c(4) species as related to evolution of c(4) photosynthesis 总被引:3,自引:2,他引:1
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This study was undertaken to examine the degree of Kranz anatomy development in the species intermediate to C3 and C4 types (C3-C4) in Panicum, Neurachne, Flaveria, and Moricandia. In each genus, C3 and/or C4 species were used for comparison. Leaf transections from each species were examined by light and transmission electron microscopy. The percentages of leaf photosynthetic cell profiles partitioned to bundle sheaths were higher in C4 than in C3 species, while C3-C4 species tended to be in between. However, percentages for C3-C4 species in Moricandia and some C3-C4Flaveria species were not greater than C3. When expressed on a cell profile area basis, C3-C4 species partitioned more photosynthetic tissue to bundle sheaths than C3 species in Moricandia, but not in Flaveria. Neurachne minor S. T. Blake (C3-C4) partitioned a very small portion of cell profile area to the inner bundle sheaths (5%) compared to Neurachne munroi F. Muell (C4) (21%). The percentage of organelles partitioned to bundle sheaths was much greater in C3-C4 than in C3 species. The average C3 percentages for mitochondria plus peroxisomes were 19, 8, and 19.5% for Neurachne, Flaveria, and Moricandia, respectively, compared to 41, 29, and 46.5% for the C3-C4 species. The CO2 compensation concentration was negatively related to the partitioning of tissue to bundle sheaths and to the percentage of organelles in bundle sheaths. It is concluded that all of the C3-C4 species examined have developed some degree of Kranz anatomy and that this altered anatomy is involved in their reduced apparent photorespiration. 相似文献
10.
MAYUMI YOSHIMURA 《Physiological Entomology》2013,38(3):226-232
Variations in δ13C and δ15N might arise from differences in nutrient allocation. Residence times of δ13C and δ15N vary among tissues depending on metabolic turnover rates. However, because of their small size, entire individual insects are generally used as single samples in isotope analyses. The present study aimed to determine the degree of isotope similarity among regions of the adult body and eggs in four species of Plecoptera (Amphinemura sp., Sweltsa sp., Kamimuria tibialis Pictet and Ostrovus sp.). Levels of δ13C and δ15N differ between the four species, being lowest in Amphinemura sp., and with δ15N being highest in Sweltsa sp. Egg masses contain consistently the lowest values of δ13C in the four species, with the δ15N value of eggs being highest in K. tibialis and Ostrovus sp., and lower in Amphinemura and Sweltsa spp. In Sweltsa sp., the δ15N levels of the dermal layers and cuticle are lowest, whereas the δ13C values of the dermal layers and cuticle are almost equal to those in other regions of the body, except egg masses. Oviposited individuals of Amphinemura and Sweltsa spp. have lower δ15N levels than individuals that have not oviposited. The rates of metabolism and incorporation of dietary metabolites will differ depending on the body regions and species. Differences in egg ecology such as egg developmental period and egg buoyancy among species are considered to impact on the values of δ13C and δ15N. These results will be useful for understanding the nutritional status of aquatic insects and their energy allocation. 相似文献
11.
Tom Moens Sandra Vanhove Ilse De Mesel Bea Kelemen Thierry Janssens Ann Dewicke Ann Vanreusel 《Polar Biology》2007,31(1):1-13
δ13C of nematode communities in 27 sites was analyzed, spanning a large depth range (from 130 to 2,021 m) in five Antarctic regions,
and compared to isotopic signatures of sediment organic matter. Sediment organic matter δ13C ranged from −24.4 to −21.9‰ without significant differences between regions, substrate types or depths. Nematode δ13C showed a larger range, from −34.6 to −19.3‰, and was more depleted than sediment organic matter typically by 1‰ and by up
to 3‰ in silty substrata. These, and the isotopically heavy meiofauna at some stations, suggest substantial selectivity of
some meiofauna for specific components of the sedimenting plankton. However, 13C-depletion in lipids and a potential contribution of chemoautotrophic carbon in the diet of the abundant genus Sabatieria may confound this interpretation. Carbon sources for Antarctic nematodes were also explored by means of an experiment in
which the fate of a fresh pulse of labile carbon to the benthos was followed. This organic carbon was remineralized at a rate
(11–20 mg C m−2 day−1) comparable to mineralization rates in continental slope sediments. There was no lag between sedimentation and mineralization;
uptake by nematodes, however, did show such a lag. Nematodes contributed negligibly to benthic carbon mineralization. 相似文献
12.
13.
A seven-step sequential grinding procedure was applied to leaves of Atriplex rosea, Sorghum sudanense, and Spinacia oleracea to study the distribution of carboxylases and microbody enzymes. In the extracts from C4 species there were 7- to 10-fold reciprocal changes in specific activities of ribulose-1, 5-diphosphate carboxylase and phosphoenolpyruvate carboxylase. No such changes occurred in sequential extracts from spinach. No inhibitors of ribulose-1, 5-diphosphate carboxylase were detected when the mesophyll extracts of Sorghum were assayed together with spinach extracts. These results reaffirm the conclusion of others that phosphoenolpyruvate carboxylase is largely confined to the mesophyll in these species and ribulose-1, 5-diphosphate carboxylase to the bundle sheath. The specific activities of glycolate oxidase and hydroxypyruvate reductase in bundle sheath extracts were two to three times those in mesophyll fractions. Catalase behaved similarly in Atriplex rosea but in Sorghum the specific activity was virtually the same in all fractions. From the relative amounts of these enzymes present, and comparison with the data obtained from spinach, it is concluded that typical leaf peroxisomes are present in the bundle sheaths of both C4 species and in the mesophyll of Atriplex rosea. The relative enzyme activities in the mesophyll of Sorghum suggest that the microbodies there are of the non-specialized type found in many nongreen tissues. The activities of the microbody enzymes in the bundle sheath of Sorghum seem quite inadequate to support photorespiration. 相似文献
14.
Differential carbon monoxide sensitivity of cytochrome C oxidase in the leaves of c(3) and c(4) plants 总被引:1,自引:1,他引:0
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CO sensitivity of cytochrome a3 in the leaves of a number of C3 and C4 plants was monitored by the nitrate reductase assay under differing CO to O2 ratios. All the C3 plants were relatively insensitive to CO and required a high CO to O2 ratio of 40 to promote significant nitrate reductase activity. However, when treated with 2 millimolar 2,4-dinitrophenol, these leaves readily responded to CO even at low CO to O2 ratios of 10 or less. On the other hand, the leaves of all C4 plants tested, belonging to the three subgroups, were highly sensitive to CO, even at CO to O2 ratios of 5 or less. In these leaves, the uncoupler was without any effect, probably because the mitochondria, either from mesophyll or bundle sheath cells or both, lacked tight respiratory control. 相似文献
15.
Leaf carbon isotope ratios (δ13C) and photosynthetic gas exchange were measured on plants growing in hanging garden communities in southern Utah, USA. Hanging
gardens are unusual, mesic cliff communities occurring where water seeps from the sandstone bedrock in an otherwise extremely
arid region; there is very limited overlap in species distributions inside and outside these gardens. Solar exposure in hanging
gardens varied with orientation and one of the gardens (Ribbon Garden) was shaded throughout the day. The leaf δ13C values of plants in hanging gardens were significantly more negative than for plants from either nearby ephemeral wash or
riparian communities. In Ribbon Garden, the observed δ13C values were as low as −34.8‰, placing them among the most negative values reported for any terrestrial plant species growing
in a natural environment. Hanging garden plants were exposed to normal atmospheric CO2 with an average δ13C value of −7.9‰ and so the low leaf δ13C values could not be attributed to exposure to a CO2 source with low 13C content. There was a seasonal change toward more negative leaf δ13C values at the end of the growing season. The observed leaf δ13C values were consistent with photosynthetic gas exchange measurements that indicated unusually high leaf intercellular CO2 concentrations associated with the relatively low light levels in hanging gardens. Thus, extremely negative leaf δ13C values would be expected if significant amounts of the seasonal carbon gain occur at light levels low enough to be near
the light compensation point. Maximum observed photosynthetic rates varied with light levels at each of the gardens, with
maximum rates averaging 20.3, 14.6, and 3.1 μmol m−2 s−1 at Double Garden, Lost Garden, and Ribbon Garden, respectively. Leaf nitrogen contents averaged 18.5 mg g−1 in species from the more shaded hanging gardens (Lost and Ribbon). When expressed on a leaf area basis, nitrogen contents
averaged 117 mmol N m−2 at Lost Garden and 65 mmol N m−2 at Ribbon Garden (shadiest of the two gardens). Leaf nitrogen isotope ratios averaged −2.3‰ (range of −0.7 to −6.1‰), suggesting
that most of the nitrogen was derived from a biological fixation source which is most likely the Nostoc growing on the sandstone walls at the seep. These values contrast with leaf nitrogen isotope ratios of 5–9‰ which have been
previously reported for arid zone plants in nearby ecosystems.
Received: 19 January 1997 / Accepted: 19 April 1997 相似文献
16.
Enzymatic fractionation of carbon isotopes by phosphoenolpyruvate carboxylase from c(4) plants 总被引:14,自引:11,他引:3
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The carbon atoms of glucose and malate in C4 plants are 2 to 3‰ enriched in 12C with respect to atmospheric CO2; whereas these intermediates in C3 plants are 15 to 18‰ enriched with 12C with respect to atmospheric CO2. The enzymatic synthesis of malate from phosphoenolpyruvate and bicarbonate in preparations of leaves of Sorghum bicolor, Haygrazer result in a carbon isotope fractionation of about 3‰. The enzymatic synthesis of phosphoglyceric acid from ribulose 1,5-diP and CO2 in these preparations (contaminated with carbonic anhydrase) at 24 C and 37 C result in a carbon isotope fractionation of 33.7‰ and 18.3‰, respectively. These data are consistent with the conclusion that the small enrichment of 12C in the carbon atoms of malate and glucose (with respect to atmospheric CO2) in leaves of Sorghum bicolor, Haygrazer occurs at the phosphoenolpyruvate carboxylase step. 相似文献
17.
The active species of "CO(2)" and the amount of fractionation of stable carbon isotopes have been determined for a partially purified preparation of phosphoenolpyruvate (PEP) carboxylase (EC 4.1.1.31) from corn (Zea mays) leaves. The rates of the enzyme reactions, using substrate amounts of HCO(3) (-), CO(2) or CO(2) plus carbonic anhydrase, show that HCO(3) (-) is the active species of "CO(2)" utilized by PEP carboxylase. The K(m) values for CO(2) and HCO(3) (-) are 1.25 mm and 0.11 mm, respectively, which further suggest the preferential utilization of HCO(3) (-) by PEP carboxylase. The amount of fractionation of stable carbon isotopes by PEP carboxylase from an infinite pool of H(12)CO(3) (-) and H(13)CO(3) (-) was -2.03 per thousand. This enzyme fractionation (delta), together with the fractionation associated with absorption of CO(2) into plant cells and the equilibrium fractionation associated with atmospheric CO(2) and dissolved HCO(3) (-) are discussed in relation to the fractionation of stable carbon isotopes of atmospheric CO(2) during photosynthesis in C(4) plants. 相似文献
18.
Photorespiration in c(3) and c(4) plant tissue cultures: significance of kranz anatomy to low photorespiration in c(4) plants
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Kennedy RA 《Plant physiology》1976,58(4):573-575
Photorespiration rates in tissue cultures of a C4 plant, Portulaca oleracea, were compared to those in tissue cultures of a C3 plant, Streptanthus tortuosus. The C4 plant tissue cultures have one-half to one-third the photorespiration rate of the C3 plant tissue cultures and respond to varying O2 concentrations in a manner typical of C4 plants. The results suggest that the lack of detectable photorespiration in C4 plants is not related to leaf anatomy. 相似文献
19.
Effect of photoinhibitory treatments on the activity of light-activated enzymes of c(3) and c(4) photosynthetic carbon metabolism 总被引:2,自引:2,他引:0
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Exposure of maize leaves to a 3-hour photoinhibitory treatment (photon flux rate of 2,000 microeinsteins meter−2 second−1, CO2-free air) resulted in lower activities of the light-activated enzymes NADP malate dehydrogenase, pyruvate, Pi dikinase, and ribulose-5-phosphate kinase. The activities could be recovered partially either by incubating enzyme extracts with dithiothreitol or by illuminating the treated leaf in air. Several enzymes which are not light-activated were not affected by the treatment. Ribulose-5-phosphate kinase activity was also reduced when bean plants grown in low light were subjected to a similar photoinhibitory treatment. 相似文献
20.
Comparative characterization of phosphoenolpyruvate carboxylase in c(3), c(4), and c(3)-c(4) intermediate panicum species 总被引:3,自引:3,他引:0
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Various properties of phosphoenolpyruvate carboxylases were compared in leaf preparations from C3-C4 intermediate, C3, and C4Panicum species. Values of Vmax in micromoles per milligram chlorophyll per hour at pH 8.3 were 57 to 75 for the enzyme from Panicum milioides, Panicum schenckii, and Panicum decipiens (all C3-C4). The values for Panicum laxum (C3) and Panicum prionitis (C4) were 20 to 40 and 952 to 1374, respectively. The Vmax values did not change at pH 7.3 except for the C4 value, which increased about 24%. At pH 8.3, the phosphoenolpyruvate carboxylases from C3 and C3-C4 species had slightly higher Km HCO3− and lower K′ phosphoenolpyruvate values than did the C4 enzyme. With each species at pH 7.3, all K′ phosphoenolpyruvate values were 2- to 4-fold greater. 相似文献