首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
Unicellular algae grow well under limiting CO2 conditions, aided by a carbon concentrating mechanism (CCM). In C. reinhardtii, this mechanism is inducible and is present only in cells grown under low CO2 conditions. We constructed a cDNA library from cells adapting to low CO2, and screened the library for cDNAs specific to low CO2-adapting cells. Six classes of low CO2-inducible clones were identified. One class of clone, reported here, represents a novel gene associated with adaptation of cells to air. A second class of clones corresponds to the air-inducible periplasmic carbonic anhydrase I (CAH1). These clones represent genes that respond to the level of CO2 in the environment.  相似文献   

2.
Cell extracts (27000xg supernatant) of acetate grown Methanosarcina barkeri were found to have carbonic anhydrase activity (0.41 U/mg protein), which was lost upon heating or incubation with proteinase K. The activity was inhibited by Diamox (apparent K i=0.5 mM), by azide (apparent K i=1 mM), and by cyanide (apparent K i=0.02 mM). These and other properties indicate that the archaebacterium contains the enzyme carbonic anhydrase (EC 4.2.1.1). Evidence is presented that the protein is probably located in the cytoplasm. Methanol or H2/CO2 grown cells of M. barkeri showed no or only very little carbonic anhydrase activity. After transfer of these cells to acetate medium the activity was induced suggesting a function of this enzyme in acetate fermentation to CO2 and CH4. Interestingly, Desulfobacter postgatei and Desulfotomaculum acetoxidans, which oxidize acetate to 2 CO2 with sulfate as electron acceptor, were also found to exhibit carbonic anhydrase activity (0.2 U/mg protein).  相似文献   

3.
During plant tissue culture, the culture container is small and sealed; the concentration of CO2 in the microenvironment is relatively low. The plantlet growth is restrained for the shortage of CO2 in the culture container. Carbonic anhydrase is a zinc-containing metalloenzyme that catalyzes the reversible conversion of bicarbonate to CO2. The determination of carbonic anhydrase of leaves from Atractylodes lancea (thunb.) DC, Orychophragmus violaceus (L.) O.E. Schulz, Brassica juncea (L.) Czern.et Coss. cv. Luzhousileng, Brassica campestris L. cv. Chuanyou No.8, Brassica napus L cv. Oro, Brassica carinata Braun, Raphanus sativa L. var. raphanistroides Makino and their plantlets indicates that the carbonic anhydrase activity of leaves from both plantlets and fields varies from plant species to plant species, the carbonic anhydrase activity of leaves of Atractylodes lancea (thunb.) DC is the lowest among those plants, and the leaves of all plantlets are lower in carbonic anhydrase activity than the same species of plants from fields. The comparison of the growth rates of those plantlets shows that their relative growth rates are significantly different, plantlets of Atractylodes lancea have the slowest relative growth rate among those plants, and plantlets of Brassica juncea have the greatest relative growth rate. The relationship between RGR of plantlets and their CA activities is a significant linear function. It seems that there was certain correlation between carbonic anhydrase activities of plants and their growth rates. It suggests that in vitro, the greater the carbonic anhydrase activity of plantlet is, the higher its net photosynthetic rate, and the faster its growth rate. Those results offer a foundation to a rational medium choice in plant tissue culture.  相似文献   

4.
A burst of net CO2 uptake was observed during the first 3–4 min after the onset of illumination in both wild-type Chlamydomonas reinhardii in which carbonic anhydrase was chemically inhibited with ethoxyzolamide and in a mutant of C. reinhardii (ca-1-12-1C) deficient in carbonic anhydrase activity. The burst was followed by a rapid decrease in the CO2 uptake rate so that net evolution often occurred. After a 2–3 min period of CO2 evolution, net CO2 uptake again increased and ultimately reached a steady-state, positive rate. From [14CO2]-tracer studies it was determined that CO2 fixation proceeded at a nearly linear rate throughout the period of illumination. Thus, prior to reaching a steady state, there was a rapid accumulation of inorganic carbon inside the cells which apparently reached a supercritical concentration and the excess was excreted, causing a subsequent efflux of CO2. A post illumination burst of net CO2 efflux was also observed in ethoxyzolamide-inhibited wild type and ca-1 mutant cells, but not in the unihibited wild type. [14CO2]-tracer experiments revealed that this burst was the result of a collapse of a large internal inorganic carbon pool at the onset of darkness rather than a photorespiratory post-illumination burst. These results indicate that upon illumination, chemical or genetic inhibition of carbonic anhydrase initially causes an accumulation of excess inroganic carbon in C. reinhardii cells, and that unknown regulatory mechanisms correct for this imbalance by first excreting the excess inorganic carbon and then, after several dampened oscillations, achieving an equilibrium between bicarbonate uptake, bicarbonate dehydration, and CO2 fixation.  相似文献   

5.
The ammonia oxidizing bacterium Nitrosomonas europaea was grown either (a) with added bicarbonate in the absence of added CO2 (bubbled through the culture), (b) with added bicarbonate plus low added CO2 (0.03% v/v), or (c) without added bicarbonate with high added CO2 (1% v/v). Cell doubling times of 12 h were observed in 1% cultures; doubling times of 2 to 3-fold longer wre found with 0.03% CO2 and/or bicarbonate grown cultures. The specific activity of carbonic anhydrase was 40–80% lower in cultures grown on 1% CO2. These results are compared with those in heterotrophic and photosynthetic microorganisms.Scientific Contribution Number 1241 from the New Hampshire Agricultural Experiment Station  相似文献   

6.
Net photosynthesis in the submersed angiosperms Myriophyllum spicatum L. and Hydrilla verticillata (L.f.) Royal was inhibited by 21% O2, but the degree of inhibition was greater for plants in the high than in the low photorespiratory state. Increasing the CO2 concentration from 50 through 2,500 l l-1 decreased the O2 inhibition of the high-photorespiration plants in a competitive manner, but it had no effect on the O2 inhibition of plants in the low photorespiratory state. Carbonic-anhydrase activity increased by almost threefold with the induction of the low photorespiratory state. Ethoxyzolamide, an inhibitor of carbonic anhydrase, reduced the net photosynthesis of low-photorespiration Myriophyllum and Hydrilla plants by 40%, but their dark respiration was unaffected. This ethoxyzolamide inhibition of net photosynthesis exhibited a competitive response to CO2 concentration, resulting in a decrease in the apparent affinity of photosynthesis for CO2. The net photosynthesis of plants in the high photorespiratory state was inhibited only slightly by ethoxyzolamide, and this inhibition was independent of the CO2 level. Ethoxyzolamide treatment caused an increase in the O2 inhibition of net photosynthesis of plants in the low photorespiratory state. Ethoxyzolamide increased the low CO2 compensation points of low-photorespiration Myriophyllum and Hydrilla, but the values for the high-photorespiration plants were unchanged. In comparison, the CO2 compensation points of the terrestrial plants Sorghum bicolor (C4), Moricandia arvensis (C3-C4 intermediate) and Nicotiana tabacum (C3) were unaltered by ethoxyzolamide treatment. These data indicate that the low photorespiratory state in Myriophyllum and Hydrilla is repressed by ethoxyzolamide treatment, thus implicating carbonic anhydrase as a component of the photorespiration-reducing mechanism in these plants. The competitive interaction of CO2 with ethoxyzolamide provides evidence that the low photorespiratory state in submersed angiosperms is the result of some type or types of CO2 concentrating mechanism. In Myriophyllum it may be via bicarbonate utilization, but in Hydrilla it probably takes the form of an inducible C4-type system.Abbreviations PEP phosphoenolpyruvate - RuBP ribulose bisphosphate  相似文献   

7.
Summary Six independently isolated mutants of Chlamydomonas reinhardtii that require elevated CO2 for photoautotrophic growth were tested by complementation analysis. These mutants are likely to be defective in some aspect of the algal concentrating mechanism for inorganic carbon as they exhibit CO2 fixation and inorganic carbon accumulation properties different from the wild-type. Four of the six mutants defined a single complementation group and appear to be defective in an intracellular carbonic anhydrase. The other two mutations represent two additional complementation groups.Abbreviations HS high salt medium which has 13 mM phosphate at pH 6.8 - HSA high salt plus 36 mM acetate medium - YA high salt medium with 4 g yeast extract per L and 36mM acetate - Arg arginine - cia- CO2 accumulation mutants that cannot grow on low CO2 - Ci inorganic carbon (CO2+HCO - 3 ) - CA carbonic anhydrase - mt mating type Supported in part by the McKnight Foundation and by NSF grant PCM 8005917 and published as journal article 11924 from the Michigan State Agriculatural Experiment Station  相似文献   

8.
Silvola  Jouko  Ahlholm  Urpo 《Plant and Soil》1995,(1):547-553
Birch seedlings (Betula pendula) were grown for four months in a greenhouse at three nutrient levels (fertilization of 0, 100 and 500 kg ha-1 monthy) and at four CO2 concentrations (350, 700, 1050 and 1400 ppm). The effect of CO2 concentration on the biomass production depended on the nutrient status. When mineralization of the soil material was the only source of nutrients (0 kg ha-1), CO2 enhancement reduced the biomass production slightly, whereas the highest production increase occurred at a fertilization of 100 kg ha-1, being over 100% between 350 and 700 ppm CO2. At 500 kg ha-1 the production increase was smaller, and the production decreased beyond a CO2 concentration of 700 ppm. The CO2 concentration had a slight effect on the biomass distribution, the leaves accounting for the highest proportion at the lowest CO2 concentration (350 ppm). An increase in nutrient status led to a longer growth period and increased the nutrient concentrations in the plants, but the CO2 concentration had no effect on the growth rhythm and higher CO2 reduced the nutrient concentrations.  相似文献   

9.
In the green marine alga Dunaliella tertiolecta, a CO2-concentrating mechanism is induced when the cells are grown under low-CO2 conditions (0.03% CO2). To identify proteins induced under low-CO2 conditions the cells were labelled with 35SO4 2–, and seven polypeptides with molecular weights of 45, 47, 49, 55, 60, 68 and 100 kDa were detected. The induction of these polypeptides was observed when cells grown in high CO2 (5% CO2 in air) were switched to low CO2, but only while the cultures were growing in light. Immunoblot analysis of total cell protein against pea chloroplastic carbonic anhydrase polyclonal antibodies showed immunoreactive 30-kDa bands in both high- and low-CO2-grown cells and an aditional 49-kDa band exclusively in low-CO2-grown cells. The 30-kDa protein was shown to be located in the chloroplast. Western blot analysis of the plasmamembrane fraction against corn plasma-membrane AT-Pase polyclonal antibodies showed 60-kDa bands in both high- and low-CO2 cell types as well as an immunoreactive 100-kDa band occurring only in low-CO2-grown cells. These results suggest that there are two distinct forms of both carbonic anhydrase and plasma-membrane ATPase, and that one form of each of them can be regulated by the CO2 concentration.Abbreviations CA carbonic anhydrase - DIC dissolved inorganic carbon (CO2+ HCO3 ) - CCM CO2-concentrating mechanism - low CO2 air containing 0.03% CO2 - high CO2 air supplemented with 5% CO2 (v/v) We thank Prof. John Coleman for providing antibodies raised against pea chloroplast CA, Dr. James V. Moroney for providing antibodies raised against the 37-kDa periplasmic carbonic anhydrase of CO2 Chlamydomonas reinhardtii, and Prof. Leonard T. Robert for a gift of corn plasma-membrane 100-kDa ATPase antibodies. We thank Dr. Jeanine Olsen (University of Groningen, the Netherlands) for style comments. This work was supported by the Institute Tecnológico de Canarias (Spain).  相似文献   

10.
Cyanobacteria, algae, aquatic angiosperms and higher plants have all developed their own unique versions of photosynthetic CO2 concentrating mechanisms (CCMs) to aid Rubisco in efficient CO2 capture. An important aspect of all CCMs is the critical roles that the specialised location and function that various carbonic anhydrase enzymes play in the overall process, participating the interconversion of CO2 and HCO3 species both inside and outside the cell. This review examines what we currently understand about the nature of the carbonic anhydrase enzymes, their localisation and roles in the various CCMs that have been studied in detail. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

11.
Thalli of Ulva reticulata Forskaal, Ulva rigida C. Ag., and Ulva pulchra Jaasund were incubated at different concentrations of dissolved CO2. Incubation at a high CO2 concentration resulted in decreased oxygen evolution rate and lower affinity for inorganic carbon at high pH conditions, i.e. the ability to use HCO3 as a carbon source was reduced. This effect was reversible, and plants regained this HCO3 uptake capacity when transferred to air concentrations of CO2. The phytosynthetic oxygen evolution rate of plants grown at high CO2 concentration was reduced by high O2 concentrations, whereas thalli and protoplasts from cultures grown at air concentration were not affected. This is interpreted as a deactivation of the carbon-concentrating mechanism during conditions of high CO2 resulting in high photorespiration when plants are exposed to high O2 concentrations. Protoplasts were not affected by high O2 to the same extent and were not able to utilize HCO3 from the medium. The algae were able to grow at very low CO2 concentrations, but growth was suppressed when an inhibitor of external carbonic anhydrase was present. Assay of carbonic anhydrase activities showed that external and internal CA activities were lower in plants grown at a high CO2 concentration compared to plants grown at a low concentration of CO2. Possible mechanisms for HCO3 utilization in these Ulva species are discussed.  相似文献   

12.
Polypeptides of 21, 36 and 37 kDa are induced in the unicellular green alga Chlamydomonas reinhardtii Dang. when cells are transferred from high (2%) to low (0.03%) CO2 concentrations. The synthesis of these polypeptides is correlated with the induction of the CO2-concentrating mechanism. In this work we studied the effect of the growth conditions on the synthesis of these polypeptides with the aim of clarifying whether the induction of all three of these low-CO2-inducible polypeptides requires the same environmental factor. Our results showed that induction of the 21- and 36-kDa polypeptides under low-CO2 conditions occurred only in the light, while the 37-kDa periplasmic carbonic anhydrase (EC 4.2.1.1) was induced in light, darkness, and in both synchronous and asynchronous cultures. In addition, induction of these polypeptides appeared to be determined more by the O2/CO2 ratio than by the CO2 concentrations. None of these polypeptides could be induced in either of two different mutants of C. reinhardtii, one lacking ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) and the other with inactive enzyme. Our results indicate that the 21- and 36-kDa polypeptides are regulated by a mechanism different from that controlling the 37-kDa polypeptide.Abbreviations pCA (periplasmic) carbonic anhydrase - Rubisco ribulose-1,5-bisphosphate carboxylase/oxygenase - TAP Trisacetate phosphate medium The authors thank Prof. M. Spalding (Iowa State University, USA) for providing antisera to LIP-21 and LIP-36. We thank Prof. S. Bartlett and Dr. J. Moroney (Louisiana State University, USA) for providing antibodies to C. reinhardtii, Rubisco and 37-kDa pCA, respectively. This work was supported by the Instituto Tecnologico de Canarias.  相似文献   

13.
The carbonic anhydrase (EC 4.2.1.1) of Rhodospirillum rubrum has been purified to apparent homogeneity and some of its properties have been determined. The enzyme was cytoplasmic and was found only in photosynthetically grown cells. It had a molecular weight of about 28,000, and was apparently composed of two equal subunits. The amino acid composition was similar to that of other reported carbonic anhydrases except that the R. rubrum enzyme contained no arginine. The isoelectric point of the enzyme was 6.2 and the pH optimum was 7.5. It required Zn(II) for stability and enzymatic activity. The K m(CO2) was 80 mM. Typical carbonic anhydrase inhibition patterns were found with the R. rubrum enzyme. Strong acetazolamide and sulfanilamide inhibition confirmed the importance of Zn(II) for enzymatic activity as did the anionic inhibitors iodide, and azide. Other inhibitors indicated that histidine, sulfhydryl, lysine and serine residues were important for enzymatic activity.Abbreviation CA carbonic anhydrase In memory of R. Y. Stanier  相似文献   

14.
To study the effect of elevated CO2 concentration on plant growth and photosynthesis, two clones ofHevea brasiliensis were grown in polybags and exposed to elevated concentration (700±25ppm) for 60 days. There was higher biomass accumulation, leaf area and better growth when compared to ambient air grown plantso From A/Ci curves it is clear that photosynthetic rates increases with increase in CO2 concentrations. After 60 days of exposure to higher CO2 concentration, a decrease in the carbon assimilation rate was noticed.  相似文献   

15.
Barbehenn RV  Karowe DN  Chen Z 《Oecologia》2004,140(1):96-103
The increasing CO2 concentration in Earths atmosphere is expected to cause a greater decline in the nutritional quality of C3 than C4 plants. As a compensatory response, herbivorous insects may increase their feeding disproportionately on C3 plants. These hypotheses were tested by growing the grasses Lolium multiflorum C3) and Bouteloua curtipendula C4) at ambient (370 ppm) and elevated (740 ppm) CO2 levels in open top chambers in the field, and comparing the growth and digestive efficiencies of the generalist grasshopper Melanoplus sanguinipes on each of the four plant × CO2 treatment combinations. As expected, the nutritional quality of the C3 grass declined to a greater extent than did that of the C4 grass at elevated CO2; protein levels declined in the C3 grass, while levels of carbohydrates (sugar, fructan and starch) increased. However, M. sanguinipes did not significantly increase its consumption rate to compensate for the lower nutritional quality of the C3 grass grown under elevated CO2. Instead, these grasshoppers appear to use post-ingestive mechanisms to maintain their growth rates on the C3 grass under elevated CO2. Consumption rates of the C3 and C4 grasses were also similar, demonstrating a lack of compensatory feeding on the C4 grass. We also examined the relative efficiencies of nutrient utilization from a C3 and C4 grass by M. sanguinipes to test the basis for the C4 plant avoidance hypothesis. Contrary to this hypothesis, neither protein nor sugar was digested with a lower efficiency from the C4 grass than from the C3 grass. A novel finding of this study is that fructan, a potentially large carbohydrate source in C3 grasses, is utilized by grasshoppers. Based on the higher nutrient levels in the C3 grass and the better growth performance of M. sanguinipes on this grass at both CO2 levels, we conclude that C3 grasses are likely to remain better host plants than C4 grasses in future CO2 conditions.  相似文献   

16.
Plant species differ broadly in their responses to an elevated CO2 atmosphere, particularly in the extent of nitrogen dilution of leaf tissue. Insect herbivores are often limited by the availability of nutrients, such as nitrogen, in their host plant tissue and may therefore respond differentially on different plant species grown in CO2-enriched environments. We reared gyspy moth larvae (Lymantria dispar) in situ on seedlings of yellow birch (Betula allegheniensis) and gray birch (B. populifolia) grown in an ambient (350 ppm) or elevated (700 ppm) CO2 atmosphere to test whether larval responses in the elevated CO2 atmosphere were species-dependent. We report that female gypsy moths (Lymantria dispar) reared on gray birch (Betula populifolia) achieved similar pupal masses on plants grown at an ambient or an elevated CO2 concentration. However, on yellow birch (B. allegheniensis), female pupal mass was 38% smaller on plants in the elevated-CO2 atmosphere. Larval mortality was significantly higher on yellow birch than gray birch, but did not differ between the CO2 treatments. Relative growth rate declined more in the elevated CO2 atmosphere for larvae on yellow birch than for those on gray birch. In preference tests, larvae preferred ambient over elevated CO2-grown leaves of yellow birch, but showed no preference between gray birch leaves from the two CO2 atmospheres. This differential response of gypsy moths to their host species corresponded to a greater decline in leaf nutritional quality in the elevated CO2 atmosphere in yellow birch than in gray birch. Leaf nitrogen content of yellow birch dropped from 2.68% to 1.99% while that of gray birch leaves only declined from 3.23% to 2.63%. Meanwhile, leaf condensed tannin concentration increased from 8.92% to 11.45% in yellow birch leaves while gray birch leaves only increased from 10.72% to 12.34%. Thus the declines in larval performance in a future atmosphere may be substantial and host-species-specific.  相似文献   

17.
Global atmospheric CO2 is increasing at a rate of 1.5–2 ppm per year and is predicted to double by the end of the next century. Understanding how terrestrial ecosystems will respond in this changing environment is an important goal of current research. Here we present results from a field study of elevated CO2 in a California annual grassland. Elevated CO2 led to lower leaf-level stomatal conductance and transpiration (approximately 50%) and higher mid-day leaf water potentials (30–35%) in the most abundant species of the grassland, Avena barbata Brot. Higher CO2 concentrations also resulted in greater midday photosynthetic rates (70% on average). The effects of CO2 on stomatal conductance and leaf water potential decreased towards the end of the growing season, when Avena began to show signs of senescence. Water-use efficiency was approximately doubled in elevated CO2, as estimated by instantaneous gas-exchange measurements and seasonal carbon isotope discrimination. Increases in CO2 and photosynthesis resulted in more seeds per plant (30%) and taller and heavier plants (27% and 41%, respectively). Elevated CO2 also reduced seed N concentrations (9%).  相似文献   

18.
Net O2 evolution, gross CO2 uptake and net HCO inf3 su– uptake during steady-state photosynthesis were investigated by a recently developed mass-spectrometric technique for disequilibrium flux analysis with cells of the marine cyanobacterium Synechococcus PCC7002 grown at different CO2 concentrations. Regardless of the CO2 concentration during growth, all cells had the capacity to transport both CO2 and HCO inf3 su– ; however, the activity of HCO inf3 su– transport was more than twofold higher than CO2 transport even in cyanobacteria grown at high concentration of inorganic carbon (Ci = CO2 + HCO inf3 su– ). In low-Ci cells, the affinities of CO2 and HCO inf3 su– transport for their substrates were about 5 (CO2 uptake) and 10 (HCO inf3 su– uptake) times higher than in high-Ci cells, while air-grown cells formed an intermediate state. For the same cells, the intracellular accumulated Ci pool reached 18, 32 and 55 mM in high-Ci, air-grown and low-Ci cells, respectively, when measured at 1 mM external Ci. Photosynthetic O2 evolution, maximal CO2 and HCO inf3 su– transport activities, and consequently their relative contribution to photosynthesis, were largely unaffected by the CO2 provided during growth. When the cells were adapted to freshwater medium, results similar to those for artificial seawater were obtained for all CO2 concentrations. Transport studies with high-Ci cells revealed that CO2 and HCO inf3 su– uptake were equally inhibited when CO2 fixation was reduced by the addition of glycolaldehyde. In contrast, in low-Ci cells steady-state CO2 transport was preferably reduced by the same inhibitor. The inhibitor of carbonic anhydrase ethoxyzolamide inhibited both CO2 and HCO inf3 su– uptake as well as O2 evolution in both cell types. In high-Ci cells, the degree of inhibition was similar for HCO inf3 su– transport and O2 evolution with 50% inhibition occurring at around 1 mM ethoxyzolamide. However, the uptake of CO2 was much more sensitive to the inhibitor than HCO inf3 su– transport, with an apparent I50 value of around 250 M ethoxyzolamide for CO2 uptake. The implications of our results are discussed with respect to Ci utilisation in the marine Synechococcus strain.Abbreviations Chl chlorophyll - Ci inorganic carbon (CO2 + HCO inf3 su– ) - CA carbonic anhydrase - CCM CO2-concentrating mechanism - EZA ethoxyzolamide - GA glycolaldehyde - K1/2 concentration required for half-maximal response - Rubisco ribulose-1,5,-bisphosphate carboxylase-oxygenase D.S. is a recipient of a research fellowship from the Deutsche Forschungsgemeinschaft (D.F.G.). In addition, we are grateful to Donald A. Bryant, Department of Molecular and Cell Biology and Center of Biomolecular Structure Function, Pennsylvania State University, USA, for sending us the wild-type strain of Synechococcus PCC7002.  相似文献   

19.
The activities of ribulose 1,5-bisphosphate carboxylase and of carbonic anhydrase were studied in cell-free extracts of two symbiotic Chlorella strains isolated from Paramecium bursaria and from Spongilla sp., and of two nonsymbiotic strains of Chlorella (Chlorella fusca and Chlorella vulgaris) cultivated at varied CO2-concentrations. The symbiotic Chlorella of Paramecium bursaria differs distinctly from the other Chlorella strains by a higher activity of ribulose 1,5-bisphosphate carboxylase, which is independent of the actual CO2-concentration, and by a lack of carbonic anhydrase activity. These properties are discussed with respect to their ecological significance.Abbreviations CA carbonic anhydrase - Pbi Paramecium bursaria isolate - RuBP ribulose 1,5-bisphosphate Dedicated to Prof. Dr. André Pirson on the occasion of his 70th birthday  相似文献   

20.
In assessing the capacity of plants to adapt to rapidly changing global climate, we must elucidate the impacts of elevated carbon dioxide on reproduction, fitness and evolution. We investigated how elevated CO2 influenced reproduction and growth of plants exhibiting a range of floral morphologies, the implications of shifts in allocation for fitness in these species, and whether related taxa would show similar patterns of response. Three herbaceous, annual species each of the genera Polygonum, Ipomoea, and Cassia were grown under 350 or 700 ppm CO2. Vegetative growth and reproductive output were measured non-destructively throughout the full life span, and vegetative biomass was quantified for a subsample of plants in a harvest at first flowering. Viability and germination studies of seed progeny were conducted to characterize fitness precisely. Early vegetative growth was often enhanced in high-CO2 grown plants of Polygonum and Cassia (but not Ipomoea). However, early vegetative growth was not a strong predictor of subsequent reproduction. Phenology and production of floral buds, flowers, unripe and abscised fruits differed between CO2 treatments, and genera differed in their reproductive and fitness responses to elevated CO2. Polygonum and Cassia species showed accelerated, enhanced reproduction, while Ipomoea species generally declined in reproductive output in elevated CO2. Seed quality and fitness (in terms of viability and percentage germination) were not always directly correlated with quantity produced, indicating that output alone may not reliably indicate fitness or evolutionary potential. Species within genera typically responded more consistently to CO2 than unrelated species. Cluster analyses were performed separately on suites of vegetative and reproductive characters. Some species assorted within genera when these reproductive responses were considered, but vegetative responses did not reflect taxonomic affinity in these plants. Congeners may respond similarly in terms of reproductive output under global change, but fitness and prognoses of population persistence and evolutionary performance can be inferred only rarely from examination of vegetative characters alone.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号