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On the metabolic origin of the carbon isotope composition of CO 2 evolved from darkened light‐acclimated leaves in Ricinus communis
Author(s) -
Gessler Arthur,
Tcherkez Guillaume,
Karyanto Oka,
Keitel Claudia,
Ferrio Juan Pedro,
Ghashghaie Jaleh,
Kreuzwieser Jürgen,
Farquhar Graham D.
Publication year - 2009
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2008.02672.x
Subject(s) - ricinus , isotopes of carbon , euphorbiaceae , botany , carbon fibers , composition (language) , chemistry , biology , environmental chemistry , total organic carbon , materials science , linguistics , philosophy , composite number , composite material
Summary• The 13 C isotopic signature (δ 13 C) of CO 2 respired from plants is widely used to assess carbon fluxes and ecosystem functioning. There is, however, a lack of knowledge of the metabolic basis of the δ 13 C value of respired CO 2 . • To elucidate the physiological mechanisms driving 12 C/ 13 C fractionation during respiration, the δ 13 C of respired CO 2 from dark‐acclimated leaves during the night, from darkened leaves during the light period, and from stems and roots of Ricinus communis was analysed. The δ 13 C of potential respiratory substrates, the respiratory quotient and the activities of phospho enol pyruvatecarboxylase (PEPc) and key respiratory enzymes were also measured. • It is shown here that the CO 2 evolved from darkened light‐acclimated leaves during the light period is 13 C‐enriched, and that this correlates with malate accumulation in the light and rapid malate decarboxylation just after the onset of darkness. Whilst CO 2 evolved from leaves was generally 13 C‐enriched (but to a lesser extent during the night), CO 2 evolved from stems and roots was depleted compared with the putative respiratory substrates; the difference was mainly caused by intensive PEPc‐catalysed CO 2 refixation in stems and roots. • These results provide a physiological explanation for short‐term variations of δ 13 C in CO 2 , illustrating the effects of variations of metabolic fluxes through different biochemical pathways.