‘Green’ …yet wasting energy? - mitochondrial respiration in plants

Plant mitochondria are characterized by the presence of both phosphorylating (cytochrome) and non-phosphorylating (alternative) pathways, the activity of which directly affects the efficiency of mitochondrial energy conservation. The cyanide-insensitive AOX (alternative oxidase) is located on the inner surface of the inner membrane, results in the oxidation of ubiquinol and the net reduction of oxygen to water, is non-protonmotive and is considered to be one of the newest members of the di-iron carboxylate group of proteins. In thermogenic tissues it plays a key role in pollination and the maintenance of a warm environment for the flower, whereas in non-thermogenic tissues functions include acting as an energy overflow, part of the oxygen defence mechanism and maintaining plant growth homoeostasis.