Isolation of Mitochondria from Orobanche, a "Total" Root Angiospermic Parasite

Mitochondria were isolated from the scapes of Orobanche cernua. On the basis of comparative studies with four media, a mannitol grinding medium was selected at a slightly alkaline pH and supplemented with EDTA, metabisulphite, BSA and soluble PVP. Various intermediates of the Krebs cycle, pyruvate, glutamate and NADH were oxidized by the isolated particles, though with different efficiencies. The rate of oxidation was steady for every intermediate tested over a 60 min period, except for NADH. In the majority of cases, the oxidation was accompanied by efficient coupling with phosphorylation. Antimycin A led to significant reduction in the oxygen uptake in the presence of succinate and complete suppression of phosphate-esterification. The amount of protein recovered in the mitochondrial fraction was comparable with the reported recoveries from a number of plant tissues. The biochemical integrity of mitochondria in the particulate fraction appeared possible from: (a) the absence of respiratory response to added cytochrome c during the oxidation of succinate, (b) insignificant oxidation of exogenously added pyruvate in the absence of sparker and (c) the ability to satisfactorily couple phosphorylation to the oxidation of a number of substrates.