Determination of the Average Partial Pressure of CO2 in Chloroplasts From Leaves of Several C3 Plants

1991 ◽  
Vol 18 (3) ◽  
pp. 287 ◽  
Author(s):  
SV Caemmerer ◽  
JR Evans
Keyword(s):  
Partial Pressure ◽  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Isotope Composition ◽  
Co2 Assimilation ◽  
Carbon Isotope Composition ◽  
C3 Plants ◽  
Isotope Discrimination ◽  
Partial Pressure Of Co2 ◽  
Transfer Conductance

Measurements of CO2 and water vapour exchange by leaves were combined with measurements of carbon isotope composition (13C/12C) of CO2 in the air passing over the leaf. Carbon isotope discrimination during CO2 uptake was determined from the difference in carbon isotope composition of the air leaving the leaf chamber with or without a leaf enclosed. Leaves of wheat plants grown with different nitrogen nutrition and leaves of several other species were examined. The measurements, made at different irradiances for a given leaf, showed that carbon isotope discrimination was strongly correlated with the rate of CO2 assimilation as well as the ratio of intercellular to ambient partial pressure of CO2, pI/pa. A function relating carbon isotope discrimination to the rate of CO2 assimilation was used to estimate the CO2 transfer conductance, gw, from the substomatal cavities to the sites of carboxylation for individual leaves. The photosynthetic capacity correlated with the CO2 transfer conductance, gw, and the average ratio of chloroplastic to intercellular partial pressure of CO2, pI/pa, was 0.7. This means that in general under high irradiance, the ratio of chloroplastic to ambient partial pressure of CO2 is about 0.5. In wheat, variation in gw was correlated with the chloroplast surface area appressing intercellular airspaces.

Carbon Isotope Discrimination measured Concurrently with Gas Exchange to Investigate CO2 Diffusion in Leaves of Higher Plants

1986 ◽  
Vol 13 (2) ◽  
pp. 281 ◽  
Author(s):  
JR Evans ◽  
TD Sharkey ◽  
JA Berry ◽  
GD Farquhar
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Carbon Isotope ◽  
Higher Plants ◽  
Isotope Composition ◽  
Co2 Assimilation ◽  
Carbon Isotope Composition ◽  
C3 Plants ◽  
Isotopic Discrimination ◽  
Co2 Diffusion

Conventional gas-exchange techniques that measure the stomatal conductance and rate of CO2 assimilation of leaves were combined with measurements of the carbon isotope composition of CO2 in air passing over a leaf. Isotopic discrimination during uptake was determined from the difference in the carbon isotope composition of air entering and leaving the leaf chamber. Isotopic discrimination measured over the short term correlated strongly with that determined from combusted leaf material. Environmental conditions were manipulated to alter the relative influences of stomatal conductance and carboxylation on the discrimination of carbon isotopes by intact leaves. With C3 plants, discrimination increased as the gradient in partial pressure of CO2 across the stomata decreased. For C4 plants there was little change in discrimination despite substantial changes in the diffusion gradient across the sto- mata. These results are consistent with, and provide the first direct experimental support for, theoretical equations describing discrimination during photosynthesis. Despite uncertainties about various processes affecting carbon isotope composition, the resistance to the transfer of CO2 from the intercellular airspaces to the sites of carboxylation in the mesophyll chloroplasts was estimated using this technique. For wheat the estimated resistance was 1.2-2.4 m2 s bar mol -1.

scholarly journals Carbon (δ13C) and Nitrogen (δ15N) Stable Isotope Composition Provide New Insights into Phenotypic Plasticity in Broad Leaf Weed Rumex acetosa under Allelochemical Stress

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2449 ◽  
Author(s):  
M. Hussain ◽  
Manuel Reigosa ◽  
Adele Muscolo
Keyword(s):  
Phenolic Compounds ◽  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Isotope Composition ◽  
Dry Weight ◽  
Carbon Isotope Composition ◽  
Inhibitory Effects ◽  
Rumex Acetosa ◽  
Isotope Discrimination ◽  
Broad Leaf

Phenolic compounds, hydroquinone and cinnamic acid derivatives have been identified as major allelochemicals with known phytotoxicity from allelopathic plant Acacia melanoxylon R. Br. Several phenolic compounds such as ferulic acid (FA), p-hydroxybenzoic acid (pHBA) and flavonoid (rutin, quercetin) constituents occur in the phyllodes and flowers of A. melanoxylon and have demonstrated inhibitory effects on germination and physiological characteristics of lettuce and perennial grasses. However, to date, little is known about the mechanisms of action of these secondary metabolites in broad-leaved weeds at ecophysiological level. The objective of this study was to determine the response of Rumex acetosa carbon isotope composition and other physiological parameters to the interaction of plant secondary metabolites (PSM) (FA and pHBA) stress and the usefulness of carbon isotope discrimination (Δ13C) as indicative of the functional performance of intrinsic water use efficiency (iWUE) at level of plant leaf. R. acetosa plant were grown under greenhouse condition and subjected to PSM stress (0, 0.1, 0.5, 1.0, and 1.5 mM) for six days. Here, we show that FA and pHBA are potent inhibitors of Δ13C that varied from 21.0‰ to 22.9‰. Higher pHBA and FA supply enhanced/retard the Nleaf and increased the Cleaf while ratio of intercellular CO2 concentration from leaf to air (Ci/Ca) was significantly decreased as compared to control. Leaf water content and leaf osmotic potential were decreased following treatment with both PSM. The Ci/Ca decreased rapidly with higher concentration of FA and pHBA. However, iWUE increased at all allelochemical concentrations. At the whole plant level, both PSM showed pronounced growth-inhibitory effects on PBM and C and N concentration, root fresh/dry weight, leaf fresh/dry weight, and root, shoot length of C3 broad leaf weed R. acetosa. Carbon isotope discrimination (Δ) was correlated with the dry matter to transpiration ratio (transpiration efficiency) in this C3 species, but its heritability and relationship to R. acetosa growth are less clear. Our FA and pHBA compounds are the potent and selective carbon isotope composition (δ13C) inhibitors known to date. These results confirm the phytotoxicity of FA and pHBA on R. acetosa seedlings, the reduction of relative water content and the induction of carbon isotope discrimination (Δ) with lower plant biomass.

Genetic variation in carbon isotope discrimination and its relationship to growth under field conditions in full-sib families of Piceamariana

1995 ◽  
Vol 25 (1) ◽  
pp. 39-47 ◽  
Author(s):  
Lawrence B. Flanagan ◽  
Kurt H. Johnsen
Keyword(s):  
Genetic Variation ◽  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Leaf Tissue ◽  
Tree Height ◽  
Strong Negative Correlation ◽  
Isotope Discrimination ◽  
Sib Families

Measurements of the stable carbon isotope composition of leaf tissue were made on Piceamariana (Mill.) B.S.P trees from four full-sib families grown on three different field sites at the Petawawa National Forestry Institute, Ontario, Canada. The four families chosen exhibited genetic variation for growth characteristics. Genetic variation was also observed for carbon isotopic discrimination (Δ) among the families of P. mariana. In addition, a strong correlation occurred between Δ values measured on trees in 1991 and 1992, two years that had very different precipitation and temperature conditions during the growing season, indicating that the ranking of individual trees remained almost constant between years. A strong, negative correlation was observed between average carbon isotope discrimination and average tree height for the four families on the driest, least productive site, as was expected based on leaf photosynthetic characteristics. There was no significant correlation, however, between Δ values and growth on the other two study sites, where productivity was higher.

Transpiration effciency and its relationship with carbon isotope discrimination under well-watered and water-stressed conditions in Stylosanthes scabra

1998 ◽  
Vol 49 (7) ◽  
pp. 1039 ◽  
Author(s):  
Bala R. Thumma ◽  
Bodapati P. Naidu ◽  
Don F. Cameron ◽  
Len M. Bahnisch
Keyword(s):  
Carbon Isotope ◽  
Drought Resistance ◽  
Carbon Isotope Discrimination ◽  
Negative Relationship ◽  
C3 Plants ◽  
Breeding Programs ◽  
Isotope Discrimination ◽  
Matter Production ◽  
Stylosanthes Scabra ◽  
High Degree

Stylosanthes scabra cv. Seca is a widely sown tropical pasture legume in northern Australia and has a high degree of drought resistance. Identification of traits contributing to the drought resistance of Seca may be valuable for use in breeding programs. Transpiration efficiency (TE) has been suggested as one such trait contributing to drought resistance. Carbon isotope discrimination (Δ) has been proposed for estimating TE indirectly in C3 plants. A glasshouse experiment was conducted using 8 accessions of S. scabra to identify whether Seca differs in TE from other accessions of S. scabra and to determine the relationship between TE and Δ under both well-watered and water-stressed treatments. Seca maintained the highest TE (lowest Δ) under both control and stress treatments, and leaf Δ was significantly and negatively correlated with TE under both control and stress conditions. A significant and negative relationship was found between Δ and dry matter production under stress treatment. The interaction between accession and watering treatment was not significant for either TE or Δ. We also found a signirficant agreement between the performance in the field and in the laboratory for these 8 accessions. These results indicate that TE could be one of the significant factors contributing to drought resistance of Seca. Furthermore, Δ and/or specific leaf area may be useful as selection criteria in breeding programs to identify the lines with high TE.

Short-Term Measurements of Carbon Isotope Discrimination in Several C4 Species

1992 ◽  
Vol 19 (3) ◽  
pp. 263 ◽  
Author(s):  
SA Henderson ◽  
SV Caemmerer ◽  
GD Farquhar
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Isotope Composition ◽  
Leaf Gas Exchange ◽  
Short Term ◽  
Isotope Discrimination ◽  
C4 Species ◽  
Linear Relationships ◽  
Partial Pressures ◽  
Wide Range

Carbon isotope discrimination (Δ) and leaf gas-exchange were measured simultaneously for a number of C4 species. Linear relationships were found between A and the ratio of intercellular to ambient partial pressures of CO2, pI/pa. These data were used to estimate the fraction of CO2 released by C4-acid decarboxylation in the bundle sheath, which subsequently leaks out to the mesophyll. We define this fraction as the leakiness of the system and it is also a measure of the extent to which phosphoenolpyruvate (PEP) carboxylations exceed ribulose 1,5-bisphosphate (RuBP) carboxylations. For Sorghum bicolor and Amaranthus edulis, leakiness was estimated at 0.2 and was constant over a wide range of irradiances (between 480 and 1600 μmol quanta m-2 s-1), intercellular CO2 pressures (between 30 and 350 μbar) and leaf temperatures (from 21�C to 34�C). At irradiances less than 240 μmol quanta m-2 s-1, leakiness appeared to increase. For a number of dicotyledonous and monocotyledonous species, of the various C4-decarboxylation types, leakiness was also estimated at 0.2. Contrary to expectation, amongst the 11 species examined, those with suberised lamellae did not show lower values of leakiness than those without suberised lamellae. For one NAD-ME and one PCK monocot, the estimates of leakiness were significantly higher at 0.30 and 0.25, respectively. Long-term discrimination (assessed from carbon isotope composition of leaf dry matter) did not correlate well with these short- term measures of discrimination. We suggest that this may be due to differences between species in fractionations occurring after photosynthesis.

Carbon Isotope Discrimination during C4 Photosynthesis: Insights from Transgenic Plants

1997 ◽  
Vol 24 (4) ◽  
pp. 487 ◽  
Author(s):  
Susanne von Caemmerer ◽  
Martha Ludwig ◽  
Anthony Millgate ◽  
Graham D. Farquhar ◽  
Dean Price ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Co2 Assimilation ◽  
Small Subunit ◽  
Bundle Sheath ◽  
Cauliflower Mosaic Virus ◽  
35S Promoter ◽  
Coding Region ◽  
Isotope Discrimination ◽  
Flaveria Bidentis

We have measured the discrimination against 13C during CO2 assimilation in Flaveria bidentis wild type plants and in transgenic Flaveria bidentis plants transformed (1) with an antisense RNA construct targeted to the nuclear encoded gene for the small subunit of Rubisco—these plants had reduced amounts of Rubisco, decreased CO2 assimilation rates and increased carbon isotope discrimination, which was also evident in the carbon isotope discrimination of leaf dry matter; and (2) transformed with the mature coding region of carbonic anhydrase, CA, from tobacco (Nicotiana tabacum) in the sense direction under the control of the cauliflower mosaic virus 35S promoter—these plants had slightly increased CA activity in the mesophyll as well as a 2–4-fold increase in CA activity in the bundle-sheath cells. The introduction of tobacco CA manifested itself by a reduction in CO2 assimilation rate and an increase in carbon isotope discrimination. We suggest that the increased carbon isotope discrimination is a result of increased bicarbonate leakage out of the bundle sheath.

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