In chlorophylkras soybean (Glycine max L.) cell suspensioo cultures glucose uptake has been studied using the analogue 3‐O‐methyIglucose. Uptake could be distinguished into: a) a high affinity phase with Km= 0.06 mM and b) a low affinity phase with Km 2.0 mM. The uptake of glucose was accompanied by H+‐cotransport with a stoichiometry of 0.3 H+ per molecule 3‐O‐methylglucose. Experiments in which sugar uptake was measured in the presence of various inhibitors of respiration and photosynthesis demonstrated that the glucose uptake system was dependent on energy metabolism and the ATP‐content of the cells. Efflux experiments in the presence of the uncoupler dinitrophenol confirmed this energy dependency. Glucose uptake did not decrease before the ATP‐content of the cells had decreased considerably.

Chloramphenicol (CAP), an inhibitor of the mitochondrial protein synthesis inhibits callus induction and subsequent growth of potato tuber tissue discs. Tissue respiration increase did not occur in the presence of CAP. Both with and without CAP the initially CN−-sensitive tissue becomes totally CN−-resistant in 1–2 weeks. CAP blocks the development of mitcohondrial cytochrome oxidase. A gradual decrease in the activities of cytochrome oxidase and of cytochrome pathway-mediated mitochondrial respiration is found in CAP-tissue. The mitochondrial alternative pathway which is absent in mitochondria from freshly sliced tissue develops during incubation both in the absence and presence of CAP. The alternative pathway is only operative in uninhibited state III respiration in mitochondria from CAP-tissue. Cycloheximide, an inhibitor of the cytoplasmic protein synthesis inhibits the developments of the alternative pathway and of the cytochrome pathway. Alcohol dehydrogenase activity increases tenfold in the tissue during two weeks of incubation on media with and without CAP. Alcohol production in the tissue did not take place in the controls nor in the CAP-treated tissue.

Mg++ ions have two effects on mitochondrial NADH-consuming respiration: the first is a stimulation of state III respiration. This effect decreases after wounding and subsequent incubation of the tissue. The site of action of Mg++ is at the external NADH dehydrogenase; the decrease in stimulation after wounding is probably not due to an increase in the Mg++ concentration in the intermembrane space.

The resistance of respiration to KCN induced in potato tuber tissue after wounding is located in the mitochondria and sensitive to metal chelators. The succinate-consuming respiration of isolated mitochondria becomes resistant after wounding, while the NADH-consuming respiration remains KCN-sensitive. The alternative oxidase most likely is located at the succinate dehydrogenase complex. From the inhibition characteristics of metal chelators it can be concluded that the alternative oxidase functions also in uninhibited respiration.

Cytochrome c has two stimulatory effects on respiration of mitochondria especially those from wounded potato tuber. In the first place a stimulation of succinate- and NADH-consuming, antimycin-A-sensitive respiration, which reaches a maximal value at low cytochrome c concentrations, has been found. In the second place, at higher concentrations of cytochrome c a stimulation of NADH-consuming respiration occurs, which is antimycin-A-resistant, but KCN-sensitive. This antimycin-A-resistant, NADH-consuming respiration is absent, when no cytochrome c is added to the reaction medium. It is insensitive to metal chelators, to which the antimycin-A-and KCN-resistant plant mitochondrial alternative oxidase is sensitive. By measurements of NADH-cytochrome c reductase activities a corresponding antimycin-A-resistant NADH-cytochrome c reductase has been found, which is insensitive to osmotic shock treatment. A localization of this antimycin-A-resistant electron transport with NADH as the electron donor in the outer mitochondrial membrane is likely. In the mitochondrial preparations cytochrome c might stimulate by acting as an electron-carrier between the outer membrane reductase and the inner membrane cytochrome oxidase. A big increase of the outer membrane mediated electron transport in the mitochondria has been observed after wounding of potato tuber tissue. The ability of the tissue to produce this electron transport pathway after wounding disappeared after prolonged storage of the tubers. A possible function of this electron transport pathway in fatty acid desaturation during the wound-reaction is suggested.

Respiration of potato tuber discs increases during incubation for 1 day at 25 °C to a value which is roughly twice as high as the respiration immediately after slicing. During the storage of potato tubers the respiration level of non-incubated discs and that reached by incubated slices declines, mainly in the period from harvest to january.

After mechanical injury of potato tubers (Solanum tuberosum L. var. Bintje) the levels of NAD+, NADH, NADP+ and NADPH were determined in extracts of the tuber tissue and its mitochondrial fraction. The incubation periods after wounding varied from five hours to three days.

Phosphorylase isoenzyme patterns obtained by the use of polyacrylamide gel electrophoresis technique were studied in relation to starch metabolism, localization, and organ differences. The following plants were investigated: Solanum tuberosum (L), Vicia faba (L), Phaseolus vulgaris (L) and Allium cepa (L). In potato tubers nine phosphorylase isoenzymes were found during the period of starch synthesis, while in a period of starch breakdown only two isoenzymes were observed. In seeds of Vicia and Phaseolus, a relation was also found between starch metabolism and the occurrence of phosphorylase isoenzymes. In extracts from potato amyloplasts only one isoenzyme was detectable. There is a correlation between the activity of this isoenzyme and the amount of amyloplasts present in different organs.

Polyacrylamide gel electrophoretic patterns of soluble proteins from intact potato tubers and from wounded tuber tissue were identical. The patterns from diseased tissue showed some minor differences not before 3–4 days after inoculation. It is concluded that primarily proteins of minor fractions are involved in protein synthesis after wounding or infection.