Influence of Growth Temperature on Respiratory Characteristics of Mitochondria from Callus-Forming Potato Tuber Discs

The uninhibited respiration of mitochondria, isolated from potato tuber discs (Solanum tuberosum L. cv. Bintje) incubated on a callus-inducing medium at 28 degrees C, is higher than that of mitochondria from tissue incubated at 8 degrees C. This respiration is composed of a CN-sensitive and a CN-resistant part. The capacity of the CN-resistant alternative oxidase pathway is larger in mitochondria from 28 degrees C tissue than in mitochondria from 8 degrees C tissue (35% and 8% of uninhibited respiration, respectively). The alternative pathway is operative both in mitochondria from 28 degrees C tissue and 8 degrees C tissue.The observed difference in uninhibited respiration, is not only caused by lower values of respiration via the alternative pathway in mitochondria from 8 degrees C tissue, but also by lower values of respiration via the cytochrome pathway.A positive correlation has been demonstrated between the incubation temperature (ranging from 4-37 degrees C) and the relative capacity of respiration via alternative pathway in the mitochondria. Induction of alternative pathway is not directly correlated with growth (in terms of increase in fresh weight) of the potato tuber discs.