共查询到20条相似文献,搜索用时 15 毫秒
1.
M. DURANCEAU J. GHASHGHAIE F. BADECK E. DELEENS & G. CORNIC 《Plant, cell & environment》1999,22(5):515-523
The variations in δ 13 C in both leaf carbohydrates (starch and sucrose) and CO2 respired in the dark from the cotyledonary leaves of Phaseolus vulgaris L. were investigated during a progressive drought. As expected, sucrose and starch became heavier (enriched in 13 C) with decreasing stomatal conductance and decreasing p i / p a during the first half (15 d) of the dehydration cycle. Thereafter, when stomata remained closed and leaf net photosynthesis was near zero, the tendency was reversed: the carbohydrates became lighter (depleted in 13 C). This may be explained by increased p i / p a but other possible explanations are also discussed. Interestingly, the variations in δ 13 C of CO2 respired in the dark were correlated with those of sucrose for both well-watered and dehydrated plants. A linear relationship was obtained between δ 13 C of CO2 respired in the dark and sucrose, respired CO2 always being enriched in 13 C compared with sucrose by ≈ 6‰. The whole leaf organic matter was depleted in 13 C compared with leaf carbohydrates by at least 1‰. These results suggest that: (i) a discrimination by ≈ 6‰ occurs during dark respiration processes releasing 13 C-enriched CO2 ; and that (ii) this leads to 13 C depletion in the remaining leaf material. 相似文献
2.
Hilary J. Crompton C. P. Lloyd-Jones D. G. Hill-Cottingham 《Physiologia plantarum》1981,51(2):189-194
When whole plants were exposed to 14 CO2 , almost the same amount of radioactivity was taken up initially by each leaf regardless of its position on the stem and of the presence of beans at that node. Thus, although developing beans are a powerful sink for assimilated carbon, they do not increase the CO2 uptake by adjoining leaves.
The distribution of labelled assimilates 6 hours after feeding14 CO2 to a single leaf for 1 hour varied with both the position of the treated leaf and the stage of development of the plant. Before any flowers were set most of the radioactivity from all expanded leaves moved downwards to the roots and the stem below the treated leaf (lower stem). Later, during pod-fill, the upper leaves maintained this supply to the roots and lower stem, whilst most of the carbon translocated from the lower and mid-stem leaves went to the beans. However, we found no exclusive relationship between a leaf and the supply to beans developing on the same node.
The amount of radioactivity moving out of a source leaf at a fruiting node increased over successive samplings up to 48 h; the pattern of distribution of the14 CO2 however remained virtually unchanged. 相似文献
The distribution of labelled assimilates 6 hours after feeding
The amount of radioactivity moving out of a source leaf at a fruiting node increased over successive samplings up to 48 h; the pattern of distribution of the
3.
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
4.
The photosynthetic rate of Lemna gibba was measured as 14 CO2 uptake at the beginning of and after 1 h DCMU treatment during the separate excitation of PS I (703 nm), mainly PS II (662 nm) and the combined excitation of both photosystems (662 + 703 nm) in 2 and 21% oxygen. The results show the Warburg effect. Photosynthesis was significantly reduced by DCMU whenever PS II was excited, at 662 nm and 662 + 703 nm. Photosynthetic enhancement was greater in 21 than in 2% oxygen in both the treated and untreated plants.
Photorespiratory14 CO2 release was only affected by DCMU treatment at 662 + 703 nm. It was significantly decreased in 21% O2 and significantly increased in 2% O2 as compared to the controls without DCMU. The 14 C-glycolate remaining in the plant after photosynthesis/photorespiration measurements was reduced whenever the electron supply to PS I was low.
These data support the hypothesis that a relationship exists between glycolate metabolism and photosynthesis via the electron transport chain where electrons from the oxidation of glycolate are donated to PS I when the electron supply from water is low. 相似文献
Photorespiratory
These data support the hypothesis that a relationship exists between glycolate metabolism and photosynthesis via the electron transport chain where electrons from the oxidation of glycolate are donated to PS I when the electron supply from water is low. 相似文献
5.
Seasonal patterns of [14 C]-labeled photosynthate distribution within two intensively cultured Populus clones with contrasting phenology ( P. tristis × P. balsamifera cv. 'Tristis no. 1'; P. × euramericana cv. Eugenei) were investigated during the establishment year. During active shoot elongation upper mature leaves exported 14 C acropetally to the expanding leaves and elongating internodes, and basipetally to the stem. Little 14 C was exported to lower mature leaves or lateral branches. At budset the 14 C export pattern shifted dramatically in the basipetal direction, i.e., to the lower stem, hardwood cutting, and roots. The timing of budset was the primary factor determining the differences between the clones, except that in all cases Tristis exported more 14 C to the roots than Eugenei. After budset lower mature leaves had a similar export pattern to upper leaves, but the quantity of 14 C exported to the roots was slightly higher. The results confirm the importance of autumn foliage for root growth in poplar. Clonal differences in seasonal patterns of photosynthate distribution offer potential for the poplar breeder seeking to match a clone's growth pattern with the specific growing season of the site. 相似文献
6.
Günter Döhler Robert C. Worrest Irene Biermann Joachim Zink 《Physiologia plantarum》1987,70(3):511-515
Uptake of [15 N]-ammonia was more sensitive to UV-B exposure than the total 14 CO2 fixation rate of Lithodesmium variabile Takano. Short-term UV-B radiation (15 min) had practically no effect on the kinetics of [15 N]-ammonia, whereas there was an effect on [14 C]-bicarbonate uptake rate. A significant reduction was found after 30 and 60 min UV-B stress. The time course of photosynthetic uptake of 15 NH4 Cl at several wavelengths was markedly depressed at shorter wavelengths (irradiation with WG 280). A short-term (11 min) exposure to ultraviolet radiation had no influence on the [14 C]-labeled photosynthetic products. However, the [15 N]-label of several amino acids and the ratio of [15 N]-glutamine to [15 N]-glutamic acid varied after irradiation with different ultraviolet wavebands. The results are discussed with reference to UV damage to the key enzymes of nitrogen metabolism. 相似文献
7.
The effects of drought stress and season on both allocation of photosynthates to stems and leaves and potential for stem rubber synthesis were studied in guayule ( Parthenium argentatum Gray USDA line 11604). Two-year-old plants grown under field conditions in the Negev desert of Israel were subjected to different irrigation regimes, and water status was assessed by measuring the relative water content (RWC). Undetached plant tips were exposed to a 1 h pulse of 14 CO2 , followed by a 24 h chase. 14 C fixed and translocated to different plants parts and notably 14 C incorporation into rubber and resin fractions was determined. The potential of detached branch slices to incorporate [14 C]-acetate into rubber was also studied. A higher percentage of fixed 14 C was translocated from shoot tips in winter (28–30%) than in summer (15–18%). The percentage of [14 C]-acctate incorporated into the rubber fraction by stem slices was maximal in winter (20%) and minimal in summer (3–5%) in both cases in the absence of drought stress. In summer the translocation of photosynthates into stems was inversely related to plant RWC, dropping from 18% three days after irrigation to 3% 14 days later, and the potential of stems to synthesise rubber was high under drought conditions and low in well irrigated plants. 相似文献
8.
Effects of elevated ozone on CO2 uptake and leaf structure in sugar maple under two light environments 总被引:2,自引:2,他引:0
The interactive effects of ozone and light on leaf structure, carbon dioxide uptake and short-term carbon allocation of sugar maple ( Acer saccharum Marsh.) seedlings were examined using gas exchange measurements and 14 C-macroautoradiographic techniques. Two-year-old sugar maple seedlings were fumigated from budbreak for 5 months with ambient or 3 × ambient ozone in open-top chambers, receiving either 35% (high light) or 15% (low light) of full sunlight. Ozone accelerated leaf senescence, and reduced net photosynthesis, 14 CO2 uptake and stomatal conductance, with the effects being most pronounced under low light. The proportion of intercellular space increased in leaves of seedlings grown under elevated ozone and low light, possibly enhancing the susceptibility of mesophyll cells to ozone by increasing the cumulative dose per mesophyll cell. Indeed, damage to spongy mesophyll cells in the elevated ozone × low light treatment was especially frequent. 14 C macroautoradioraphy revealed heterogeneous uptake of 14 CO2 in well defined areole regions, suggesting patchy stomatal behaviour in all treatments. However, in seedlings grown under elevated ozone and low light, the highest 14 CO2 uptake occurred along larger veins, while interveinal regions exhibited little or no uptake. Although visible symptoms of ozone injury were not apparent in these seedlings, the cellular damage, reduced photosynthetic rates and reduced whole-leaf chlorophyll levels corroborate the visual scaling of whole-plant senescence, suggesting that the ozone × low light treatment accelerated senescence or senescence-like injury in sugar maple. 相似文献
9.
A. KOHZU T. YOSHIOKA T. ANDO M. TAKAHASHI K. KOBA & E. WADA 《The New phytologist》1999,144(2):323-330
The natural abundance of 13 C and 15 N was measured in basidiocarps of at least 115 species in 88 genera of ectomycorrhizal, wood-decomposing and litter-decomposing fungi from Japan and Malaysia. The natural abundance of 13 C and 15 N was also measured in leaves, litter, soil and wood from three different sites. 15 N and 13 C were enriched in ectomycorrhizal and wood-decomposing fungi, respectively, relative to their substrates. Ectomycorrhizal and wood-decomposing fungi could be distinguished on the basis of their δ13 C and δ15 N signatures. Although there was high variability in the isotopic composition of fungi, the following isotope- enrichment factors (ε, mean±SD) of the fungi relative to substrates were observed:
εectomycorrhizal fungi/litter = 6.1±0.4‰15 N
εectomycorrhizal fungi/wood = 1.4±0.8‰13 C
εwood-decomposing fungi/wood = −0.6±0.7‰15 N
εwood-decomposing fungi/wood = 3.5±0.9‰13 C
The basis of isotope fractionation in C metabolism from wood to wood-decomposing fungus is discussed. 相似文献
ε
ε
ε
ε
The basis of isotope fractionation in C metabolism from wood to wood-decomposing fungus is discussed. 相似文献
10.
Abstract: Production of [14 C]acetylcholine and 14 CO2 was examined by using tissue prisms from neocortex, hippocampus, and striatum from rats aged approximately 5 months, 13 months, and 27 months. [14 C]Acetylcholine synthesis in the striatum showed highly significant decreases with age for measurements in the presence of both 5 m m - and 31 m m -K+ , contrasting with the lack of significant change in 14 CO2 production in this region. The neocortex and hippocampus showed only small changes, especially when comparison was made between 13-month and senescent animals. Measurements of the release of [14 C]acetylcholine and influence of atropine on this release confirmed the relative stability with age of the cholinergic system in the neocortex. 相似文献
11.
In the sugar beet plant ( Beta vulgaris L. ssp. altissima ) the vascular bundles of old leaves lead to the center and those of young leaves to the periphery of the storage root. Whether the flux of assimilates follows these anatomical routes was tested by applying 14 CO2 for 4 h to either an old (10th) or a young (20th) leaf in intact sugar beet plants. Four-month-old plants, which had about 30 leaves, were used in the experiment. The 14 C distribution in the storage root was measured by autoradiography and counting in about 20 cross and longitudinal sections per root.
About 37% of assimilated14 C from an old leaf and 23% from a young leaf were exported within 24 h. Although some 14 C moved into younger leaves, most was exported into the storage root. During its rapid movement towards the root tip, which took place perferentially in the orthostichon belonging to the [14 C]-treated leaf, the label spread laterally.
The autoradiograms indicate that the distribution of assimilates within the storage root is roughly determined by the course of the vascular bundles extending from the source leaf. The fine distribution, however, seems to be controlled by sucrose gradients between storage cells. 相似文献
About 37% of assimilated
The autoradiograms indicate that the distribution of assimilates within the storage root is roughly determined by the course of the vascular bundles extending from the source leaf. The fine distribution, however, seems to be controlled by sucrose gradients between storage cells. 相似文献
12.
Confirmation of operative acetate, H2 /CO2 and methanol methanogenic pathways in the solid-state refuse fermentation 总被引:2,自引:2,他引:0
By use of the radiolabelled substrates sodium [1–14 C] acetate, sodium [2–14 C] acetate, NaH14 CO3 and 14 CH3 OH, three of the possible methanogenic pathways in fermenting refuse were confirmed. Due to the absence of a methanol pool, however, the relative contribution of each could not be determined. Circumstantial evidence for an operative trimethylamine pathway was gained but not confirmed whilst preliminary attempts to stimulate methanogenesis in refuse by supplementation with mono-and dimethylamine proved unsuccessful. 相似文献
13.
Abstract: Cl and Na transport by the lateral ventricle (LVCP) and fourth ventricle (4VCP) choroid plexuses were examined by kinetic analysis of 36 Cl and 22 Na uptake into the choroid plexus-CSF system of the adult rat. Both radioisotopes required more than 5 h to reach steady-state distribution in the in vivo choroid plexuses and CSF after intraperitoneal injection. Whereas the LVCP and 4VCP 36 Cl steady-state spaces were comparable (55–56%), the 4VCP 22 Na space (39%) tended to be greater than the LVCP 22 Na space (36%). No evidence for inexchangeable Cl or Na was found for the choroid plexuses; the radioisotopic and chemical spaces were not significantly different. Choroid plexus 36 Cl and 22 Na uptake curves were resolved into two components, a fast component ( t 1/2 0.02–0.05 h) and a slow component ( t 1/2 0.85–1.93 h). By analysis of the distribution of [3 H]inulin, [3 H]mannitol, and 51 Cr-tagged erythrocytes within the choroid plexuses, the fast component of 36 Cl and 22 Na uptake was found to represent extracellular and erythrocyte contributions to the tissue radioactivity, whereas the slow component represented isotope movement into the epithelial cell compartment. The calculated cell [Cl] of LVCP and 4VCP, 67 mmol/kg cell water, was 3.9 times greater than that predicted by the membrane potential for passive distribution. It is postulated that Cl is actively transported into the choroid epithelial cell across the basolateral membrane; the energy source for active Cl transport may be the Na electrochemical potential gradient (˜90 mV), which is twice that of the Cl electrochemical potential gradient (˜45 mV). 相似文献
14.
Hilary J. Crompton D. G. Hill-Cottingham G. A. Hudd C. P. Lloyd-Jones 《Physiologia plantarum》1984,60(4):543-546
Whole bean plants, ev. Cockfield, grown in pots crowded or well-spaced (50 or 10 plants m2 , respectively) were treated with 14 CO2 at the pod-fill stage (25 modes) and the radioactivity in each leaf was determined after 30 min. With spaced plants the uptake was greatest in the mid-stem leaves and was proportional to leaf area. In contrast, 70% of the total assimilation took place in the upper six leaves of crowded plants and there was a steady decrease down the stem.
When14 CO2 was fed to single leaves of similar crowded plants the resultant distribution of labelled assimilates varied with the position of the treated leaf. After 6 h, 67% of the 14 C fixed by a mid-stem leaf (node 13) was recovered from the beans, whereas 76% of that from an upper leaf (node 23) had accumulated along the stem. Due to the shading of mid-stem leaves at the higher planting densities, seed yield becomes increasingly dependent upon re-distribution of assimilates from stem to beans. 相似文献
When
15.
Hamako Obata-Sasamoto Victor M. Villalobos Trevor A. Thorpe 《Physiologia plantarum》1984,61(3):490-496
Excised cotyledons of radiata pine ( Pinus radiata D. Don), cultured under shootforming (plus cytokinin) and elongating (minus cytokinin) conditions, were incubated in 14 C-glucose, 14 C-acetate or 14 C-bicarbonate at different stages of growth and differentiation. 14 CO2 was produced when the cotyledons were fed 14 C-glucose and 14 C-acetate (no measurement was made for 14 C-bicarbonate feeding). Label from these precursors was incorporated into ethanol-soluble and -insoluble fractions. The largest percentage of radioactivity was associated with the ethanol-soluble portion, which was further fractionated into lipids, amino acids, organic acids and sugars. The amount of label and the pattern of labelling associated with each of the above classes of metabolites varied with time in culture and morphogenetic behaviour of the cotyledons. In general, there was a tendency towards a high rate of incorporation of label in elongating cotyledons during the period of rapid elongation. On the other hand, a high rate of incorporation of label in shoot-forming cotyledons coincided with the period of meristematic tissue formation. The data obtained support the hypothesis that organized development in vitro involves a shift in metabolism, which precedes and is coincident with the initiation of the process. 相似文献
16.
Red clover, Trifolium pratense L., is the dominant forage legume in Sweden and is usually harvested twice per year, once in June and once in August. Two 15 N-based methods –15 N isotopic dilution (ID) and 15 N natural abundance (NA) – were used to study N2 fixation from spring until first harvest in late June, from first to second harvest in late August, and from second harvest until first frost in autumn in Umeå, Sweden. The material studied comprized three neighbouring fields carrying a first year ley, a second year ley and a third year ley. For the 15 N ID method, small amounts of highly enriched 15 N-nitrate were added to experimental plots. The non-legumes in the plots, essentially Phleum pratense L. together with Festuca pratensis L., served as reference plants for both the ID and 15 N NA measurements. Dry matter, N and 15 N were separately analysed in leaves (laminae), stems (including petioles), stubble and roots. The proportion of N derived from air (pNdfa) was then calculated for each plant part and for whole plants. Estimates of the proportion of N derived from N2 fixation (pNdfa) were always very high, usually ≥0.8. Generally, estimates of pNdfa obtained by the ID and NA methods were similar, but the ID method gave higher estimates of pNdfa than the NA method when the highest N2 fixation levels were recorded, at the August harvest. Regression analyses suggest that estimates of pNdfa in leaves could provide useful indications of pNdfa in shoots and whole T. pratense plants, thus avoiding the need for time-consuming root analyses. 相似文献
17.
18.
Manuel A. Vega Eduardo C. Santamaria Alfonsina Morales Ricardo L. Boland 《Physiologia plantarum》1985,65(4):423-426
Vitamin D3 at low concentration (10−9 M) inhibited the growth of Phaseolus vulgaris L. (cv. Contrancha) roots in vitro as measured by elongation (14 h) and [3 H]-leucine incorporation into protein (2 h), and increased their labelling with 45 Ca2+ (2 h). Cycloheximide and puromycin (50 u.M) blocked vitamin D3 stimulation of root 45 Ca2+ labelling, indicating that it is mediated by de novo protein synthesis. The calcium ionophore X-537A (10−5 JW) induced similar changes both in root elongation and 45 Ca2+ uptake (14 h). This may indicate that the inhibitory effects of the sterol on root growth are mediated by changes in Ca2+ fluxes. However, this interpretation should be further strengthened by additional studies as the ionophore may have acted on root growth, affecting physiological processes other than Ca2+ transport. 相似文献
19.
The role of methionine as a precursor in mugineic acid (MA) biosynthesis was studied by feeding 15 N-ammonium sulfate, 14 C-amino acids, and [1-14 C, 15 N]-methionine to iron-deficient barley roots ( Hordeum vulgare L. cv. Minorimugi), grown hydroponically. The incorporation of isotopes into amino acids was also examined. Methionine appears to be the most efficient precursor of the mugineic acid family (MAs) of phytosiderophores; homoserine was also incorporated into the MAs, but other amino acids such as glutamate, alanine, and γ-amino butyric acid did not act as precursors of MAs. Carbon-14 and 15 N of methionine were incorporated into MAs. This specific incorporation of 14 C and 15 N indicated that the nitrogen atoms of MAs were derived from two molecules of methionine. It is suggested that deoxymugineic acid (DMA) is probably the first phytosiderophore to be synthesized on the biosynthetic pathway of MAs. 相似文献
20.
CHUN-MEI WANG JIN-LIN ZHANG XUE-SONG LIU ZHAN LI GUO-QIANG WU JIAN-YI CAI TIMOTHY J. FLOWERS & SUO-MIN WANG 《Plant, cell & environment》2009,32(5):486-496
Puccinellia tenuiflora is a useful monocotyledonous halophyte that might be used for improving salt tolerance of cereals. This current work has shown that P. tenuiflora has stronger selectivity for K+ over Na+ allowing it to maintain significantly lower tissue Na+ and higher K+ concentration than that of wheat under short- or long-term NaCl treatments. To assess the relative contribution of Na+ efflux and influx to net Na+ accumulation, unidirectional 22 Na+ fluxes in roots were carried out. It was firstly found that unidirectional 22 Na+ influx into root of P. tenuiflora was significantly lower (by 31–37%) than in wheat under 100 and 150 m m NaCl. P. tenuiflora had lower unidirectional Na+ efflux than wheat; the ratio of efflux to influx was similar between the two species. Leaf secretion of P. tenuiflora was also estimated, and found the loss of Na+ content from leaves to account for only 0.0006% of the whole plant Na+ content over 33 d of NaCl treatments. Therefore, it is proposed that neither unidirectional Na+ efflux of roots nor salt secretion by leaves, but restricting unidirectional Na+ influx into roots with a strong selectivity for K+ over Na+ seems likely to contribute to the salt tolerance of P. tenuiflora . 相似文献