Respiration in the light measured by 12CO 2 emission in 13CO 2 atmosphere in maize leaves
By Francesco Loreto, V. Velikova, G. Marco. 2001
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The mitochondrial respiration during photosynthesis is difficult to measure and is indirectly estimated mainly in C 3 plants. Loreto et al. [(1999) Australian Journal of Plant Physiology 26, 733–736] have shown that the emission of 12 CO 2 from illuminated leaves exposed to air containing 13 CO 2 measures photorespiration and mitochondrial respiration in C 3 leaves. This method was used to measure the mitochondrial respiration in illuminated maize leaves. The 12 CO 2 emission was steady after 30 s, a time sufficient to label the CO 2 leakage from bundle sheath cells with 13 CO 2 , but not the mitochondrial respiration in the light. The emission was low (0.1–0.4 ppm or 0.2–0.4 µmol m –2 s –1 ) in a wide range of leaf temperatures and light intensities, but increased at light intensities below 200 µmol m –2 s –1 and at temperatures above 42°C. At 120 s after labelling, the leaf was darkened and the emission rapidly matched the mitochondrial respiration measured by gas exchange. The emission of 12 CO 2 in the light was inversely correlated with photosynthesis. This suggested that most of the respiratory CO 2 was refixed by photosynthesis. The amount of refixed intercellular 12 CO 2 was calculated from gas-exchange parameters. It was 60 to 90% of the tota l12 CO 2 in leaves illuminated and exposed to temperatures below 42°C. In leaves with reduced photosynthesis because of exposure to higher temperatures or low light, the 12 CO 2 refixation decreased. The sum of refixed and emitted 12 CO 2 was close to the mitochondrial respiration in the dark. This suggested that in these leaves the mitochondrial respiration was not inhibited in the light. In salt- and water-stressed leaves, however, the sum of refixed and emitted 12 CO 2 was lower than mitochondrial respiration in the dark, suggesting that the mitochondrial respiration may be inhibited in the light.
Subfields: Molecular Biology, Plant Science
View Paper: https://www.semanticscholar.org/paper/70b1821d4bb2c2dcee852a7d3ed4d5d209ea34ec
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Citations in the corpus
- High thermal acclimation potential of both photosynthesis and respiration in two lowland Plantago species in contrast to an alpine congeneric (2006, unknown): “This confirms previous observations that light reduces the Q10 of leaf respiration (Harley et al., 1992; Atkin et al., 2000a; Loreto et al., 2001; Pons & Welschen, 2003).”
- Bringing the Kok effect to light: A review on the integration of daytime respiration and net ecosystem exchange (2013, background): “…TCA precursors M, CP, P Many, summarized in Hurry et al. 2005 Refixation CO2 released from TCA cycle refixed by Calvin Cycle in stroma M, CP Loreto et al. 2001 Pinelli and Loreto 2003 Refixation does not directly inhibit respiratory processes, but can produce an observable ‘‘inhibitory’’…”
- Carbon isotope fractionation during dark respiration and photorespiration in C3 plants (2004, background): “However, refixation of respiratory CO2 has been demonstrated to occur in several studies and functions as a means to maintain an electron sink under adverse conditions (Gerbaud and Andre, 1987; Bort et al., 1996; Loreto et al., 2001).”