Correlation between the Carbon Isotope Discrimination in Leaf Starch and Sugars of C3 Plants and the Ratio of Intercellular and Atmospheric Partial Pressures of Carbon Dioxide

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.

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

Functional Plant Biology ◽

10.1071/pp9920263 ◽

1992 ◽

Vol 19 (3) ◽

pp. 263 ◽

Cited By ~ 121

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.

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Clarifying the influence of water availability and plant types on carbon isotope discrimination by C3 plants

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1102556108 ◽

2011 ◽

Vol 108 (16) ◽

pp. E59-E60 ◽

Cited By ~ 13

Author(s):

K. H. Freeman ◽

K. E. Mueller ◽

A. F. Diefendorf ◽

S. L. Wing ◽

P. L. Koch

Keyword(s):

Carbon Isotope ◽

Water Availability ◽

Carbon Isotope Discrimination ◽

C3 Plants ◽

Isotope Discrimination ◽

Influence Of Water

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Evaluation of the Use of Carbon Isotope Discrimination as a Selection Tool of Perennial Fodder Species for Temporary Pastures

Notulae Botanicae Horti Agrobotanici Cluj-Napoca ◽

10.15835/nbha3926379 ◽

2011 ◽

Vol 39 (2) ◽

pp. 34

Author(s):

Nicusor Flavius SIMA ◽

Rodica Maria SIMA ◽

Stela CUNA ◽

Gabriela CRISTEA ◽

Valentin MIHAI

Keyword(s):

Water Use Efficiency ◽

Carbon Isotope ◽

Water Use ◽

Carbon Isotope Discrimination ◽

Theoretical Models ◽

Isotope Discrimination ◽

Fodder Plants ◽

Partial Pressures ◽

Use Efficiency ◽

The Relationship

Estimation of the relationship between carbon isotope discrimination (Î”13C) in perennial fodder plants and various factors such as climate, fertilization and soil could contribute to a better selection and/or improvement of genotype of fodder species. Theoretical models of carbon isotope discrimination in plants indicate a linear relationship between Î”13C and CO2 partial pressures ratio (pi/pa) from the intercellular spaces (pi) of CO2 in leaves and from the atmosphere (pa). It is also known that between pi parameter and water-use efficiency (WUE) there is a negative correlation. Eight perennial fodder legume and grass mixtures were cultivated on three levels of fertilization in order to assess mixtures for pastures that can provide sustainable quantitative and qualitative yields. The species, which composed the mixtures, were also cultivated as pure crops on the same fertilization conditions. The results of this study indicated that in five of the six species, which composed the mixture with the highest yield, pi/pa values decreased while fertilization doses increased, most likely as a result of variation in water-use efficiency.

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

Functional Plant Biology ◽

10.1071/pp9910287 ◽

1991 ◽

Vol 18 (3) ◽

pp. 287 ◽

Cited By ~ 182

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.

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