Carbon flux around leaf-cytosolic glyceraldehyde-3-phosphate dehydrogenase introduces a 13C signal in plant glucose. (5th July 2021)

• Record Type: Journal Article
• Authors: Wieloch, Thomas; Werner, Roland Anton; Schleucher, Jürgen
• Editors: Lunn, John
• Is Part Of: Journal of experimental botany. Volume 72:Number 20(2021)
• Page Start: 7136
• Page End: 7144
• Publication Date: 2021-07-05
• Subjects: Carbon allocation -- carbon flux -- carbon stable isotopes -- cytosolic oxidation–reduction cycle -- energy metabolism -- glyceraldehyde-3-phosphate dehydrogenase -- intramolecular isotope analysis -- isotope fractionation model -- primary carbon metabolism; Botany -- Periodicals; Botany, Experimental -- Periodicals; Plant physiology -- Periodicals; 580
• DOI: 10.1093/jxb/erab316
• Languages: English
• ISSNs: 0022-0957

Abstract

Abstract : A 13 C signal at plant glucose C-4 provides information about carbon flux around leaf-cytosolic glyceraldehyde-3-phosphate dehydrogenases and associated energy metabolism. Isotope fractionation modelling provides first evidence of the cytosolic oxidation–reduction cycle. Abstract: Within the plant and Earth sciences, stable isotope analysis is a versatile tool conveying information ( inter alia ) about plant physiological and paleoclimate variability across scales. Here, we identify a 13 C signal (i.e. systematic 13 C/ 12 C variation) at tree-ring glucose C-4 and report an experimentally testable theory on its origin. We propose the signal is introduced by glyceraldehyde-3-phosphate dehydrogenases in the cytosol of leaves. It conveys two kinds of (potentially convoluted) information: (i) commitment of glyceraldehyde 3-phosphate to 3-phosphoglycerate versus fructose 1, 6-bisphosphate metabolism; and (ii) the contribution of non-phosphorylating versus phosphorylating glyceraldehyde-3-phosphate dehydrogenase to catalysing the glyceraldehyde 3-phosphate to 3-phosphoglycerate forward reaction of glycolysis. The theory is supported by 13 C fractionation modelling. Modelling results provide the first evidence in support of the cytosolic oxidation–reduction (COR) cycle, a carbon-neutral mechanism supplying NADPH at the expense of ATP and NADH, which may help to maintain leaf-cytosolic redox balances. In line with expectations related to COR cycling, we found a positive correlation between air vapour pressure deficit and 13 C discrimination at glucose C-4. Overall, 13 C-4 signal analysis may enable an improved understanding of leaf carbon and energy metabolism.