Mitochondrial Activity in Orobanche cernua from Different Regions of the Scape and as Influenced by Host

Orobanche cernua, a holoparasite, was harvested from different hosts, namely, Solanum melongena, Petunia hybrida, Lycopersicum esculentum, Solanum nigrum and Datura metel. Mitochondrial particles were isolated and they were evaluated in terms of the marker enzyme, cytochrome c oxidase, and protein in the mitochondrial fraction. Protein levels in whole homogenate and mitochondrial fraction of parasite growing on different host plants did not vary significantly, whereas the recovery of protein (% of whole homogenate) in the mitochondrial fraction of parasite growing on D. metel was higher. Cytochrome c oxidase activity in parasites growing on the three host plants varied, being highest when the parasite grew on S. melongena, followed sequentially by that on P. hybrida and D. metel. Protein in whole homogenate and mitochondrial fraction was significantly lower, 25–36% and 15–33%, respectively, in distal region when compared with the proximal region. Similarly, cytochrome oxidase and respiratory activity was significantly lower, 23– 34% and 18–23%, respectively, in the distal region of the parasite. In addition, variations in cytochrome oxidase and respiratory activity in the proximal and distal regions of the parasite growing on different hosts was also significant. Results indicated that mitochondria in haustoria-bearing proximal region of Orobanche scape play a special role to meet the metabolic demand of the parasite