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1.
G. Salahas K. Hatzidimitrakis C. D. Georgiou K. Angelopoulos N. A. Gavalas 《Plant biology (Stuttgart, Germany)》1997,110(4):309-313
The effect of phosphate, sulfate and other inorganic ions on the activity of phosphoenolpyruvate carboxylase (PEPC) from the C4 plant Cynodon dactylon were investigated for the first time, as well as their interaction with Clc-6-P, AMP and ma-late. Activation of PEPC by phosphate and sulfate ions was demonstrated and it was not dependent on the accompanying cations, something that was not clarified for PEPCs from other plant sources. No activation of this enzyme was observed by nitrate. PEPC activation was found to be competitive with glucoses-phosphate (Clc-6-P) and AMP stimulation and less sensitive to malate inhibition. This work showed that PEPC from C4plants could exhibit similar activation properties with the enzyme from CAM plants and different activation properties in plants of the same type, rendering the study of this enzyme from different plant sources necessary. 相似文献
2.
NADP-malate dehydrogenase extracted from darkened leaves of the C3 plants pea, barley, wheat and spinach was activated by reduced glutathione, a monothiol, as well as by dithiothreitol (DTT). However, in the C4 plants maize and Flaveria trinervia, only dithiothreitol could effectively activate the enzyme. There was no activation of the maize enzyme and little or no activation of the F. trinervia enzyme by glutathione. The failure of glutathione to activate NADP-MDH in leaf extracts of maize and F. trinervia may indicate there is some difference in disulfide groups of the protein compared to the C3 plant enzyme. Both DTT and glutathione could activate NADP-malate dehydrogenase in a partially purified enzyme preparation from pea leaves with or without addition of partially purified thioredoxin. However, the required concentration of reductant was lower with addition of thioredoxin than in its absence. In extracts of C3 species and the partially purified pea enzyme the level of activation after 40 to 60 min under aerobic conditions was higher (up to twofold) with DTT than with glutathione. Under anaerobic conditions, the initial rate of activation was about twice as high with DTT as with glutathione, but the total activation after 40 to 60 min was similar. Ascorbate was totally ineffective as a reducing agent in activating NADP-MDH from C3 or C4 plants, possibly due to its more positive redox potential.Abbreviations Chl
Chlorophyll
- DTT
Dithiothreitol
- GSH
Reduced Glutathione
- NADP-MDH
NADP-malate Dehydrogenase 相似文献
3.
Younès Dellero Caroline Mauve Edouard Boex-Fontvieille Valérie Flesch Mathieu Jossier Guillaume Tcherkez Michael Hodges 《The Journal of biological chemistry》2015,290(3):1689-1698
In plants, glycolate oxidase is involved in the photorespiratory cycle, one of the major fluxes at the global scale. To clarify both the nature of the mechanism and possible differences in glycolate oxidase enzyme chemistry from C3 and C4 plant species, we analyzed kinetic parameters of purified recombinant C3 (Arabidopsis thaliana) and C4 (Zea mays) plant enzymes and compared isotope effects using natural and deuterated glycolate in either natural or deuterated solvent. The 12C/13C isotope effect was also investigated for each plant glycolate oxidase protein by measuring the 13C natural abundance in glycolate using natural or deuterated glycolate as a substrate. Our results suggest that several elemental steps were associated with an hydrogen/deuterium isotope effect and that glycolate α-deprotonation itself was only partially rate-limiting. Calculations of commitment factors from observed kinetic isotope effect values support a hydride transfer mechanism. No significant differences were seen between C3 and C4 enzymes. 相似文献
4.
Studies in temperate grassland ecosystems have shown that differences in composition of C3 and C4 plant functional types can have important influences on ecosystem pools and processes. We used a plant community dynamics
model (STEPPE) linked to a biogeochemical cycling model (CENTURY) to determine how ecosystem properties in shortgrass steppe
are influenced by plant functional type composition. Because of phenological differences between C3 and C4 plants, we additionally simulated the effects of precipitation seasonality on plant communities and examined how C3 and C4 composition interacts with precipitation to affect ecosystems. The model output suggests that differences in C3 and C4 composition can lead to differences in soil organic carbon (C) and nitrogen (N) within 1000 simulation years. Soil organic
C and N (g C and N m−
2 to 0.2-m depth) were least in a 100% C4 community compared with a 100% C3 community and a mixed C3–C4 community. A change in the time of maximum precipitation from summer to spring in a simulated shortgrass steppe slightly
favored C3 plants over C4 plants. The proportion of total net primary production accounted for by C3 plants increased from 21% to 25% after 200 years, when 90 mm of precipitation was switched from summer to spring. Soil organic
matter (SOM) was relatively stable in the C4-dominated communities with respect to changes in precipitation seasonality, whereasSOM in the C3 community was sensitive to precipitation seasonality changes. These results suggest an important interaction between plant
community composition and precipitation seasonality on SOM, with phenology playing a key role.
Received 9 June 1998; accepted 6 January 1999 相似文献
5.
受损景观是由不同比例的植被斑块组成的镶嵌体,阐明植被斑块的景观结构特征对物种多样性的影响,有助于提高受损景观物种多样性保护。在塞罕坝自然保护区选取38个天然植被斑块,其中包括12个草地、11个灌木林和15个天然次生林。根据光合作用的不同途径将草本物种划分为C_3和C_4功能群。选取斑块面积、形状指数、隔离度指数及每个斑块500 m缓冲区内的森林和草地比例作为景观因子。通过结构方程模型探讨C_3、C_4草本物种丰富度与景观因子的相互关系。斑块面积(2.18—74.06 hm~2)与C_3、C_4草本及总物种丰富度分布格局均具有显著的正相关关系(P0.05),且对C_3草本的影响最大;形状指数(1.06—3.11)、隔离度指数(33.51—327.65)对C_3、C_4草本及总物种丰富度影响不显著(P0.05);C_3、C_4草本及总物种丰富度与毗邻斑块草地比例(4.20%—64.95%)呈正相关,而与森林比例(35.05%—95.80%)呈负相关。研究区斑块面积和毗邻斑块植被构成是影响C_3、C_4草本植物的主要因素。在破碎化景观中保存面积大的天然植被斑块及提高毗邻斑块草地比例是保护关键C_3、C_4草本植物物种的有效途径。 相似文献
6.
Phosphoenolpyruvate carboxylase (PEPCase, EC 4.1.1.3) is a key enzyme of C4 photosynthesis. It has evolved from ancestral non-photosynthetic (C3) isoforms and thereby changed its kinetic and regulatory properties. We are interested in understanding the molecular changes,
as the C4 PEPCases were adapted to their new function in C4 photosynthesis and have therefore analysed the PEPCase genes of various Alternanthera species. We isolated PEPCase cDNAs from the C4 plant Alternanthera pungens H.B.K., the C3/C4 intermediate plant A. tenella Colla, and the C3 plant A. sessilis (L.) R.Br. and investigated the kinetic properties of the corresponding recombinant PEPCase proteins and their phylogenetic
relationships. The three PEPCases are most likely derived from orthologous gene classes named ppcA. The affinity constant for the substrate phosphoenolpyruvate (K
0.5 PEP) and the degree of activation by glucose-6-phosphate classified the enzyme from A. pungens (C4) as a C4 PEPCase isoform. In contrast, both the PEPCases from A. sessilis (C3) and A. tenella (C3/C4) were found to be typical C3 PEPCase isozymes. The C4 characteristics of the PEPCase of A. pungens were accompanied by the presence of the C4-invariant serine residue at position 775 reinforcing that a serine at this position is essential for being a C4 PEPCase (Svensson et al. 2003). Genomic Southern blot experiments and sequence analysis of the 3′ untranslated regions of these genes indicated the existence
of PEPCase multigene family in all three plants which can be grouped into three classes named ppcA, ppcB and ppcC. 相似文献
7.
N. Dasgupta‐Schubert S. Alexander L. Sommer T. Whelan R. Alfaro Cuevas Villanueva M. E. Mendez Lopez M. W. Persans 《Engineering in Life Science》2007,7(3):259-267
This work is a study of the inter‐relationship between parameters that principally affect the metal up‐take in the plant. The relationships between the concentration of metal in the growth medium, Cs, the concentration of metal absorbed by the plant, Cp, and the total biomass achieved, M, all of which are factors relevant to the efficiency of phytoremediation of the plant, have been investigated via the macro‐physiological response of Brassica juncea seedlings to Ni(II) stress. The factorial growth experiments treated the Ni(II) concentration in the agar gel and the diurnal light quanta (DLQ) as independently variable parameters. Observations included the evidence of light enhancement of Ni toxicity at the root as well as at the whole plant level, the shoot mass index as a possible indicator of shoot metal sequestration in B. juncea, the logarithmic variation of Cp with Cs and the power‐law dependence of M on Cp. The sum total of these observations indicates that for the metal accumulator B. juncea with regard to its capacity to accumulate Ni, the overall metabolic nature of the plant is important – neither rapid biomass increase nor a high metal concentration capability favor the removal of high metal mass from the medium, but rather the plant with the moderate photosynthetically driven biomass growth and moderate metal concentrations demonstrated the ability to remove the maximum mass of metal from the medium. The implications of these observations in the context of the perceived need in phytoremediation engineering to maximize Cp and M simultaneously in the same plant, are discussed. 相似文献
8.
Phosphoenolpyruvate carboxylase (PEPCase; EC 4.1.1.31) from Flaveria trinervia Mohr (C4), F. floridana Johnston (C3–C4), and F. cronquistii Powell (C3) leaves were compared by electrotransfer blotting/enzyme-linked immunoassay (Western-blot analysis), mobility of the native enzyme in polyacrylamide gels and in isoelectric focusing (IEF) gels, peptide mapping, and in-vitro translation of RNA isolated from each plant. The PEPCases from the C3 and C3–C4 plants were very similar to each other in terms of electrophoretic mobilities on gels and isoenzyme patterns on IEF gels, and identical in peptide mapping. Quantitative differences were noted, however, in that the C3–C4 intermediate plant contained more PEPCase overall and that the relative activity of individual isoenzymes shifted between the C3 and C3–C4 intermediate PEPCases. The PEPCase from the C4 plant had a different isoenzyme pattern, a different peptide map, and was far more abundant than the other two enzymes. Western blot analysis demonstrated the cross-reactivity of PEPCases from all three Flaveria species with antibody raised against maize PEPCase. The results provide evidence, at the molecular level, that supports the view of C3–C4 intermediate species as C3-like plants with some C4-like photosynthetic characteristics, but there are differences from the C3 plant in the quantity and properties of the PEPCase from the C3–C4 intermediate plant.Abbreviations IEF
isoelectric focusing
- kDa
kilodalton
- PEPCase
phosphoenolpyruvate carboxylase
- Rubisco
Ribulose-1,5-bisphosphate carboxylase/oxygenase 相似文献
9.
The rate and extent of light activation of PEPC may be used as another criterion to distinguish C3 and C4 plants. Light stimulated phosphoenolypyruvate carboxylase (PEPC) in leaf discs of C4 plants, the activity being three times greater than that in the dark but stimulation of PEPC was limited about 30% over the dark-control in C3 species. The light activation of PEPC in leaves of C3 plants was complete within 10 min, while maximum activation in C4 plants required illumination for more than 20 min, indicating that the relative pace of PEPC activation was slower in C4 plants than in C3 plants. Similarly, the dark-deactivation of the enzyme was also slower in leaves of C4 than in C3 species. The extent of PEPC stimulation in the alkaline pH range indicated that the dark-adapted form of the C4 enzyme is very sensitive to changes in pH. The pH of cytosol-enriched cell sap extracted from illuminated leaves of C4 plants was more alkaline than that of dark-adapted leaves. The extent of such light-dependent alkalization of cell sap was three times higher in C4 leaves than in C3 plants. The course of light-induced alkalization and dark-acidification of cytosol-enriched cell sap was markedly similar to the pattern of light activation and dark-deactivation of PEPC in Alternanthera pungens, a C4 plant. Our report provides preliminary evidence that the photoactivation of PEPC in C4 plants may be mediated at least partially by the modulation of cytosolic pH.Abbreviations CAM
Crassulacean acid metabolism
- G-6-P
glucose-6-phosphate
- PMSF
phenylmethylsulfonyl fluoride
- PEPC
phosphoenolpyruvate carboxylase
- PEPC-PK
phosphoenolpyruvate ca carboxylase-protein kinase 相似文献
10.
《Plant science》1986,45(1):1-7
NADP-malate dehydrogenase (L-malate: NADP+ oxidoreductase, E.C. 1.1.1.82) was purified from the leaves of Zea mays L. and its subunit molecular weight, amino acid composition and the changes in number of thiol groups during activation were determined. The amino acid composition we found differed from that reported earlier for the Z. mays enzyme but was very similar to that reported for the enzyme isolated from pea leaves. The maize enzyme contains fewer methionine residues (3 compared to 5 in pea) but a greater total number of cysteine residues (6 compared to 3 in pea). In its inactive form (oxidised) the enzyme contained 2 thiols per subunit of which only 1 reacts with 5,5′-dithiobis(2-nitrobenzoic acid) when the enzyme is in its native form. During activation by dithiothreitol two disulphide bonds are reduced per subunit to give 4 new thiol groups. We conclude that NADP-malate dehydrogenase from leaves of the C4 plant Z. mays is very similar to the enzyme from the C3 plant pea. However, apparently two disulphide bonds are reduced during the reductive activation of the Z. mays enzyme in vitro compared with 1 disulphide bond for the pea enzyme. 相似文献
11.
Glycolate oxidase (GO; EC 1.1.3.1) was purified from the leaves of three plant species:Amaranthus hypochondriacus L.(NAD-ME type C4 dicot),Pisum sativum L. (C3 species) andParthenium hysterophorus L. (C3–C4. intermediate). A flavin moiety was present in the enzyme from all the three species. The enzyme from the C4 plant had a low specific activity, exhibited lower KM for glycolate, and required a lower pH for maximal activity, compared to the C3 enzyme. The enzyme from the C4 species oxidized glyoxylate at <10% of the rate with glycolate, while the GO from the C3 plant oxidized glyoxylate at a rate of about 35 to 40% of that with glycolate. The sensitivity of GO from C4 plant to -hydroxypyridinemethane sulfonate, 2-hydroxy-3-butynoate and other inhibitors was less than that of the enzyme from C3 source. The properties of GO fromParthenium hysterophorus, were similar to those of the enzyme fromPisum sativum. The characteristics of glycolate oxidase from leaves of a C4 plant,Amaranthus hypochondriacus are different from those of the C3 species or the C3–C4 intermediate. 相似文献
12.
Pyruvate orthophosphate dikinase of c(3) seeds and leaves as compared to the enzyme from maize 总被引:12,自引:5,他引:7
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Pyruvate orthophosphate dikinase (PPDK) was found in various immature seeds of C3 plants (wheat, pea, green bean, plum, and castor bean), in some C3 leaves (tobacco, spinach, sunflower, and wheat), and in C4 (maize) kernels. The enzyme in the C3 plants cross-reacts with rabbit antiserum against maize PPDK. Based on protein blot analysis, the apparent subunit size of PPDK from wheat seeds and leaves and from sunflower leaves is about 94 kdaltons, the same as that of the enzyme from maize, but is slightly less (about 90 kdaltons) for the enzyme from spinach and tobacco leaves. The amount of this enzyme per mg of soluble protein in C3 seeds and leaves is much less than in C4 leaves. PPDK is present in kernels of the C4 plant, Zea mays in amounts comparable to those in C4 leaves.
Regulatory properties of the enzyme from C3 tissues (wheat) are similar to those of the enzyme from C4 leaves with respect to in vivo light activation and dark inactivation (in leaves) and in vivo cold lability (seeds and leaves).
Following incorporation of 14CO2 by illuminated wheat pericarp and adjoining tissue for a few seconds, the labeled metabolites were predominantly products resulting from carboxylation of phosphoenolpyruvate, with lesser labeling of compounds formed by carboxylation of ribulose 1,5-bisphosphate and operation of the reductive pentose phosphate cycle of photosynthesis. PPDK may be involved in mechanisms of amino acid interconversions during seed development.
相似文献13.
Rhizosphere priming effects on the decomposition of soil organic matter in C4 and C3 grassland soils 总被引:1,自引:0,他引:1
Using a natural abundance 13C method, soil organic matter (SOM) decomposition was studied in a C3 plant – `C4 soil' (C3 plant grown in a soil obtained from a grassland dominated by C4 grasses) system and a C4 plant – `C3 soil' (C4 plant grown in a soil taken from a pasture dominated by C3 grasses) system. In C3 plant – `C4 soil' system, cumulative soil-derived CO2–C were higher in the soils planted with soybean (5499 mg pot–1) and sunflower (4484 mg pot–1) than that in `C4 soil' control (3237 mg pot–1) without plants. In other words, the decomposition of SOM in soils planted with soybean and sunflower were 69.9% and 38.5% faster than `C4 soil' control. In C4 plant – `C3 soil' system, there was an overall negative priming effect of live roots on the decomposition of SOM. The cumulative soil-derived CO2–C were lower in the soils planted with sorghum (2308 mg pot–1) and amaranthus (2413 mg pot–1) than that in `C3 soil' control (2541 mg pot–1). The decomposition of SOM in soils planted with sorghum and amaranthus were 9.2% and 5.1% slower than `C3 soil' control. Our results also showed that rhizosphere priming effects on SOM decomposition were positive at all developmental stages in C3 plant – `C4 soil' system, but the direction of the rhizosphere priming effect changed at different developmental stages in the C4 plant – `C3 soil' system. Implications of rhizosphere priming effects on SOM decomposition were discussed. 相似文献
14.
Question: The relationship between carbon‐13 in soil organic matter and C3 and C4 plant abundance is complicated because of differential productivity, litter fall and decomposition. As a result, applying a mass balance equation to δ13C data from soils cannot be used to infer past C3 and C4 plant abundance; only the proportion of carbon derived from C3 and C4 plants can be estimated. In this paper, we compare δ13C of surface soil samples with vegetation data, in order to establish whether the ratio of C3:C4 plants (rather than the proportion of carbon from C3 and C4 plants) can be inferred from soil δ13C. Location: The Tsavo National Park, in southeastern Kenya. Methods: We compare vegetation data with δ13C of organic matter in surface soil samples and derive regression equations relating the δ13C of soil organic matter to C3:C4 plant abundance. We use these equations to interpret δ13C data from soil profiles in terms of changes in inferred C3:C4 plant ratio. We compare our method of interpretation with that derived from a mass balance approach. Results: There was a statistically significant, linear relationship between the δ13C of organic matter in surface soil samples and the natural logarithm of the ratio of C3:C4 plants in the 100m2 surrounding the soil sample. Conclusions: We suggest that interpretation of δ13C data from organic matter in soil profiles can be improved by comparing vegetation surveys with δ13C of organic matter in surface soil samples. Our results suggest that past C3 plant abundance might be under‐estimated if a mass balance approach is used. 相似文献
15.
Feng Ying Wen Zhi Bin Gulnur Sabirhazi Wang Xi Yong 《Contemporary Problems of Ecology》2014,7(3):301-307
The paper analyses total of 58 samples representing 32 species of the 14 genera of shrub plant of the carbon isotope composition in Xinjiang representatives of Chenopodiaceae and a detailed discussion on the various factors that can influence them. The value of 38 samples fall between ?14.88‰ and ?11.55‰ with a mean of ?13.34‰, and values of 20 samples between ?27.93‰ and ?22.877‰ with a mean of ?25.38‰. So we obtained a total of 21 of C4 species (59.4%) and 11 of C3 species (40.6%) from 32 species studied Chenopodiaceae of shrubs plant. Then the relationship of plant-carbon-isotope and environmental factors has been analyzed. The results showed that the importance environmental factors for the δ13C-value of the Shrubs was annual precipitation (0.78) > temperature (0.66) > elevation (0.55). The three principal components has important factors to influence on C3/C4 shrub plant distribution. Environmental conditions play significant roles in the distribution and ecophysiological features of different photosynthetic types and even change the photosynthetic pathways. On the other hand, such as geographic location, Sunshine duration, evaporation capacity are more or less correlation with δ13C values, however, they would be interfered by annual precipitation. Desert plants to adapt to drought conditions by increasing water use efficiency (WUE) strategy. In short, plant physiology function is sensitive and timely to adapt environmental change. 相似文献
16.
17.
Low root temperature effects on soybean nitrogen metabolism and photosynthesis 总被引:10,自引:9,他引:1
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Duke SH Schrader LE Henson CA Servaites JC Vogelzang RD Pendleton JW 《Plant physiology》1979,63(5):956-962
The influences of low root temperature on soybeans (Glycine max [L.] Merr. cv. Wells) were studied by germinating and maintaining plants at root temperatures of 13 and 20 C through maturity. At 42 days from the beginning of imbibition, 13 and 20 C plants were switched to 20 and 13 C, respectively. Plants were harvested after 63 days. Control plants (13 C) did not nodulate, whereas those switched to 20 C did and at harvest had C2H2 reduction rates of 0.2 micromoles per minute per plant. Rates of C2H2 reduction decreased rapidly in plants switched from 20 to 13 C; however, after 2 days, rates recovered to original levels (0.8 micromoles per minute per plant) and then began a slow decline until harvest. Arrhenius plots of C2H2 reduction by whole plants indicated a large increase in the energy of activation below the inflection at 15 C. Highest C2H2 reduction rates (1.6 micromoles per minute per plant) were at 58 days for the 20 C control. Root respiration rates followed much the same pattern as C2H2 reduction in the 20 C control and transferred plants. At harvest, roots from 13 C-treated plants had the highest activities for malate dehydrogenase, glutamate oxaloacetate transaminase, and phosphoenolpyruvate carboxylase. Roots from transferred plants had intermediate activities and those from the 20 C treatment the lowest activities. Newly formed nodules from plants switched from 13 to 20 C had much higher glutamate dehydrogenase than glutamine synthetase activity. 相似文献
18.
Rubisco activase (Rca) facilitates the release of sugar‐phosphate inhibitors at Rubisco catalytic sites during CO2 fixation. Most plant species express two Rca isoforms, the larger Rca‐α and the shorter Rca‐β, either by alternative splicing from a single gene or expression from separate genes. The mechanism of Rubisco activation by Rca isoforms has been intensively studied in C3 plants. However, the functional role of Rca in C4 plants where Rubisco and Rca are located in a much higher [CO2] compartment is less clear. In this study, we selected four C4 bioenergy grasses and the model C4 grass setaria (Setaria viridis) to investigate the role of Rca in C4 photosynthesis. All five C4 grass species contained two Rca genes, one encoding Rca‐α and the other Rca‐β, which were positioned closely together in the genomes. A variety of abiotic stress‐related motifs were identified in the Rca‐α promoter of each grass, and while the Rca‐β gene was constantly highly expressed at ambient temperature, Rca‐α isoforms were expressed only at high temperature but never surpassed 30% of Rca‐β content. The pattern of Rca‐α induction on transition to high temperature and reduction on return to ambient temperature was the same in all five C4 grasses. In sorghum (Sorghum bicolor), sugarcane (Saccharum officinarum), and setaria, the induction rate of Rca‐α was similar to the recovery rate of photosynthesis and Rubisco activation at high temperature. This association between Rca‐α isoform expression and maintenance of Rubisco activation at high temperature suggests that Rca‐α has a functional thermo‐protective role in carbon fixation in C4 grasses by sustaining Rubisco activation at high temperature. 相似文献
19.
Using a combination of gas-exchange and chlorophyll fluorescence measurements, low apparent CO2/O2 specificity factors (1300 mol mol?1) were estimated for the leaves of two deciduous tree species (Fagus sylvatica and Castanea sativa). These low values contrasted with those estimated for two herbaceous species and were ascribed to a drop in the CO2 mole fraction between the intercellular airspace (Ci) and the catalytic site of Rubisco (Cc) due to internal resistances to CO2 transfer. Cc. was calculated assuming a specificity of Rubisco value of 2560 mol mol?1. The drop between Ci and Cc was used to calculate the internal conductance for CO2 (gi). A good correlation between mean values of net CO2 assimilation rate (A) and gi was observed within a set of data obtained using 13 woody plant species, including our own data. We report that the relative limitation of A, which can be ascribed to internal resistances to CO2 transfer, was 24–30%. High internal resistances to CO2 transfer may explain the low apparent maximal rates of carboxylation and electron transport of some woody plant species calculated from A/Ci curves. 相似文献
20.
Distribution of biomass of species differing in photosynthetic pathway along an altitudinal transect in southeastern wyoming grassland 总被引:4,自引:1,他引:4
Summary Based on the physiological characteristics and responses of C3, C4, and CAM plants to environmental factors, it is generally predicted that C4 and CAM plants will become more abundant with increasing temperature and decreasing precipitation. To test this prediction, the relative contribution of each photosynthetic type to total plant community biomass was examined at seven study areas along an altitudinal transect in southeastern Wyoming grassland. In going from high (2,652 m) to low (1,405 m) elevation along this transect, mean annual temperature increased and annual precipitation decreased.The percentage of C4 biomass composing each study area decreased with increasing elevation, while the percentage of C3 biomass increased. All elevations had a significantly higher percentage of C4 biomass in August than in June, reflecting the warm season growth characteristic of C4 plants. Regressions of relative abundance of photosynthetic types on climatic variables showed that both mean annual temperature and annual precipitation were equally reliable as predictors of C3–C4 biomass, although we feel that temperature is of primary importance in explaining our observations. CAM species were present at all elevations, but showed no trends in biomass distribution with respect to elevation. 相似文献