Respiratory Activity of the Mitochondrial Fractions Isolated from Healthy Potato Tubers and from Tuber Tissue Incubated after Cutting or Infection with Ceratocystis fimbriata

Abstract

Mitochondria were prepared from intact potato tubers (Solanum tuberosum), from tuber slices (cut tissue), and from the tissue adjacent to the invaded parts of 1-cm thick slices inoculated with C. fimbriata (infected tissue). All preparations showed respiratory control by ADP; the oxidative and phosphorylative processes were coupled, also after infection. The respitatory control and ADP/O ratios of mitochondria from infected and cut tissues proved to be a lower than in mitochondria from healthy tubers. The changes in N content and cytochrome oxi-dase activity in the mitochondria ran in parallel, indicating changes in the amount of mitochondria. The cytochrome oxidase activity per N was practically the same in all preparations. The experimental results suggest that the amount of mitochondria in cut tissue was higher than in intact tubers. No increase in mitochondrial number was found in preparations from infected tissue when compared with the fractions from incubated intact tubers. Even a decrease was observed 3 days after inoculation.