A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2 : evidence from carbon isotope discrimination in paleo and CO2 enrichment studies

2016 ◽  
Vol 22 (2) ◽  
pp. 889-902 ◽  
Author(s):  
Steven L. Voelker ◽  
J. Renée Brooks ◽  
Frederick C. Meinzer ◽  
Rebecca Anderson ◽  
Martin K.-F. Bader ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Carbon Isotope ◽  
Woody Plants ◽  
Carbon Isotope Discrimination ◽  
Leaf Gas Exchange ◽  
Co2 Enrichment ◽  
Isotope Discrimination ◽  
Ambient Co2

Partitioning of Carboxylase Activity in Nitrogen-Stressed Sugarcane and Its Relationship to Bundle Sheath Leakiness to CO2, Photosynthesis and Carbon Isotope Discrimination

1995 ◽  
Vol 22 (6) ◽  
pp. 903 ◽  
Author(s):  
SA Ranjith ◽  
FC Meinzer ◽  
MH Perry ◽  
M Thom
Keyword(s):  
Gas Exchange ◽  
Carbon Isotope ◽  
Carbon Isotope Discrimination ◽  
Leaf Gas Exchange ◽  
Bundle Sheath ◽  
Rubisco Activity ◽  
Carboxylase Activity ◽  
Isotope Discrimination ◽  
N Supply

We studied the effects of external nitrogen (N) supply on ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity, phosphoenolpyruvate carboxylase (PEPC) activity, leaf gas exchange, carbon isotope discrimination (Δ), and bundle sheath leakiness to CO2 (Φ) in two cultivars of the C4 grass, sugarcane (Saccharum spp. hybrid). In addition to reducing overall levels of carboxylase activity and therefore photosynthetic rates, reduced N supply altered the partitioning of carboxylase activity. Under long-term N stress (4 months) Rubisco activity decreased more than PEPC activity causing significant reductions in the Rubisco/PEPC activity ratio, a measure of the ratio of C3 to C4 cycle activity. Concurrent determinations of Δ for leaf dry matter and the prevailing ratio of intercellular to ambient partial pressure of CO2 (pI/pa) during leaf gas exchange suggested that the decreased partitioning of N to Rubisco activity under long-term N stress led to increased Φ and reduced photosynthetic efficiency. The two cultivars studied maintained similar PEPC activities but differed genetically in regard to investment of N in Rubisco. Greater investment of N in Rubisco was associated with higher rates of photosynthesis and growth at similar or slightly lower leaf N content, indicating that greater relative investment of N in Rubisco activity also led to higher N-use efficiency. The results suggest that regulation of the ratio of C3 to C4 pathway activity and its consequences for Φ may play a key role in the photosynthetic performance and growth of C4 grasses under both favourable and stressful conditions.

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.

GAS EXCHANGE, GROWTH, YIELD AND BEVERAGE QUALITY OF COFFEA ARABICA CULTIVARS GRAFTED ON TO C. CANEPHORA AND C. CONGENSIS

2001 ◽  
Vol 37 (2) ◽  
pp. 241-252 ◽  
Author(s):  
J. I. FAHL ◽  
M. L. C. CARELLI ◽  
H. C. MENEZES ◽  
P. B. GALLO ◽  
P. C. O. TRIVELIN
Keyword(s):  
Stomatal Conductance ◽  
Gas Exchange ◽  
Carbon Isotope ◽  
Coffea Arabica ◽  
Carbon Isotope Discrimination ◽  
Growth Yield ◽  
Carbon Gain ◽  
Dry Period ◽  
Isotope Discrimination

Gas exchange, leaf carbon isotope discrimination, growth, yield and beverage quality were evaluated for two Coffea arabica cultivars (Catuai and Mundo Novo), grafted on to C. canephora and C. congensis progenies growing in open fields. During the years 1994 to 1997, grafting resulted in an average increase in bean yield of 151 and 89% for Catuai and Mundo Novo respectively. As analysed by sensory analyses and by the ratio between the mono-isomers and di-isomers of caffeoylquinic acid, beverage quality of the C. arabica was not altered by grafting. Shoot growth was significantly greater in grafted plants, showing an increase of 52% in total leaf area compared with the non-grafted plants. Under conditions of water excess in the soil there was little difference in the transpiration and stomatal conductance rates between the grafted and non-grafted plants, but the net photosynthesis was higher in grafted plants. With an accentuated water deficit in the soil in the dry period, the grafted plants showed significantly higher transpiration and stomatal conductance rates than the non-grafted plants, and similar values to those of C. canephora. Carbon isotope discrimination was greater in the grafted plants, suggesting greater root hydraulic conductance. The results suggest that the better performance of the grafted plants during the dry period was due to the greater capacity of the root system of C. canephora to provide water to the shoot thereby maintaining greater gas exchange in the leaves and consequently a greater carbon gain.

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