Respiration in Photosynthetic Cells: Gas Exchange Components, Interactions with Photorespiration and the Operation of Mitochondria in the Light

Mitochondrial uncoupling protein is required for efficient photosynthesis

“…This process generates large quantities of NADH that must be oxidized to regenerate the NAD ϩ required for the glycine decarboxylase reaction. A large part of this oxidation is thought to occur via malate dehydrogenase activity in the mitochondrial matrix, reducing oxaloacetate to malate (27). Export of the resultant reducing equivalents from the mitochondrion as malate can supply the NADH required for the peroxisomal reactions of photorespiration (see SI Fig.…”

Oscillations of the internal CO2 concentration in tobacco leaves transferred to low CO2

“…Such oscillations in photorespiratory flux in the light could have important implications for the extent to which TCA cycle CO 2 release takes place in the light. It is well known that light inhibits CO 2 release by the TCA cycle and that the inhibition is likely linked to photorespiratory flux (see Hurry et al, 2005 for a recent review). If photorespiratory flux does indeed oscillate as we propose, then one would expect to see regular fluctuations in light inhibition of TCA cycle CO 2 release.…”

Antisense Inhibition of the 2-Oxoglutarate Dehydrogenase Complex in Tomato Demonstrates Its Importance for Plant Respiration and during Leaf Senescence and Fruit Maturation

“…When taken together, our results suggest that the activity of the OGDH is a highly sensitive metabolic juncture, and as such, they reveal the importance of mitochondrial reactions involving 2-oxoglutarate and by implication also of the mitochondrial membrane protein that mediates its transport between the cytosol and mitochondria (Picault et al, 2002). Previous studies have demonstrated that interactions between photosynthesis and respiration induce changes in metabolic pathways of primary carbon metabolism (Hurry et al, 2005;Nunes-Nesi et al, 2007b) and that, in illuminated leaves, intracellular metabolism is dynamically modulated as a function of environmental changes (Noguchi and Yoshida, 2008). Historically speaking, photosynthesis and respiration have been considered as independent pathways; however, a growing body of evidence suggests that the functions of both chloroplasts and mitochondria are closely coordinated and tightly interact through intracellular metabolite pools Raghavendra and Padmasree, 2003;Nunes-Nesi et al, 2005, 2007bNoguchi and Yoshida, 2008).That said, as described in the Introduction, alteration of the activities of the various enzymes of the mitochondrial TCA cycle resulted in diverse photosynthetic and phenotypic phenotypes.…”