Does elevated atmospheric CO₂ concentration inhibit mitochondrial respiration in green plants?

Abstract

There is abundant evidence that a reduction in mitochondrial respiration of plants occurs when atmospheric CO 2 (C a ) is increased. Recent reviews suggest that doubling the present C a will reduce the respiration rate [per unit dry weight (DW)] by 15 to 18%. The effect has two components: an immediate, reversible effect observed in leaves, stems, and roots of plants as well as soil microbes, and an irreversible effect which occurs as a consequence of growth in elevated C a and appears to be specific to C 3 species. The direct effect has been correlated with inhibition of certain respiratory enzymes, namely cytochromec-oxidase and succinate dehydrogenase, and the indirect or acclimation effect may be related to changes in tissue composition. Although no satisfactory mechanisms to explain these effects have been demonstrated, plausible mechanisms have been proposed and await experimental testing. These are carbamylation of proteins and direct inhibition of enzymes of respiration. A reduction of foliar respiration of 15% by doubling present ambient C a would represent 3 Gt of carbon per annum in the global carbon budget.Key-words: acclimation to rising CO 2 ; dark respiration; global carbon cycle; rising CO 2 .Abbreviations: ATP, adenosine triphosphate; K m , MichaelisMenton coefficient; C a , concentration of CO 2 in the air (µmol mol -1 ); NAD, oxidized nicotin adenine dinucleotide; NADH, reduced nicotin adenine dinucleotide; NADP, oxidized nicotin adenine phosphate dinucleotide; NADPH, reduced nicotine adenine phosphate dinucleotide; R, rate of respiration per unit DW [µmol g DW -1 ], Rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase; V c , max , maximum in vivo rate of carboxylation at Rubisco (µmol m -2 s -1 ).

Effects of elevated atmospheric CO 2 concentration on leaf dark respiration of Xanthium strumarium in light and in darkness

“…Leaf R measured in this manner is consequently used to assess the effects of elevated CO 2 on carbon loss on leaf, plant, and ecosystem levels (9). This is a valid approach if light affects leaf R of ambient and elevated CO 2 -grown plants to the same extent.…”

“…The magnitude of light inhibition of respiration seems to depend on the photosynthetic capacity (1), but the mechanism of light regulation of mitochondrial respiration is not clearly understood (2,3). Although there has been much study of, albeit little agreement on, the effects of elevated CO 2 on plant respiration (7)(8)(9), the effects of elevated CO 2 on mitochondrial respiration in light have been little studied and hence are largely unknown (5, 10).…”

CO<sub>2</sub> flux determination by closed-chamber methods can be seriously biased by inappropriate application of linear regression

“…As the effect of ambient CO 2 concentration changes on dark respiration has been shown to be very low or none (Grulke et al, 1990;Drake et al, 1999;Amthor, 2000;Tjoelker et al, 2001;Smart, 2004;Bunce, 2005), CO 2 flux associated with the dark respiration of aboveground biomass F R (t) is considered invariant with changing c(t) in a considered CO 2 concentration range of 200 ppm to 500 ppm. Thus, if the other environmental controls such as temperature or air moisture can be assumed constant, F R (t) can be defined as:…”

Genomic basis for stimulated respiration by plants growing under elevated carbon dioxide

“…Changes in respiration will combine with the well characterized stimulation of C 3 photosynthesis by elevated [CO 2 ] to impact the net primary productivity of ecosystems and their capacity to act as sources or sinks of carbon. Key synthesis papers have variously concluded that elevated [CO 2 ] will cause plant respiration to increase as much as 11%, decrease as much as 18%, or not change (5)(6)(7)(8). This uncertainty corresponds to an increase or decrease in carbon release to the atmosphere similar in size to current anthropogenic carbon emissions.…”

“…This uncertainty corresponds to an increase or decrease in carbon release to the atmosphere similar in size to current anthropogenic carbon emissions. The primary reason for uncertainty is that the mechanisms of plant respiratory responses to elevated [CO 2 ] have not been resolved (3,(5)(6)(7)(8). This knowledge gap also restricts our understanding at the tissue and whole-plant scales of how elevated [CO 2 ] impacts growth and crop yield.…”