Changes in Respiratory Pathways of Potato Tuber (Solanum tuberosum L.) after Various Times of Storage of the Tuber. Comparison of Wounded and Non-Wounded Tissue

Abstract

Summary 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. During the storage period the changes in activity of several parameters linked to respiration have been determined both in freshly cut slices and in incubated tissue. These parameters do not uniformly change parallel with the increase of respiration during incubation or with the decline of respiration levels during the storage period. The activity of mitochondrial malate dehydrogenase located in the matrix does not change much after wounding and incubation and decreases slowly during the storage period. Cytochrome oxidase and CN-sensitive succinate oxidase, located in the mitochondrial inner membrane slightly increase after wounding and incubation. The former rapidly decreases in activity in the first months of storage and more slowly afterwards. The latter decreases in the first months of storage and stabilizes afterwards. CN-resistant succinate oxidase activity (alternative oxidase) of the inner membrane is not present in mitochondria from non-incubated tissue. It is induced during incubation only when the potatoes have been stored for some time but is not induced immediately after harvest. Only a small activity of outer membrane located, antimycin-A resistant NADH-cytochrome c reductase could be found in freshly cut slices. During incubation it strongly increases immediately after harvest, but this increase disappears gradually during storage of the tubers. The protein content of the mitochondrial fraction roughly doubles during one day of incubation. The protein in this fraction both from fresh discs and incubated ones rises during storage of the tubers. The activity of the cytoplasmatic 6-phosphogluconate dehydrogenase doubles after incubation of discs but levels do not change throughout the storage period.