Participation of the CN-resistant Alternative Oxydase Pathway in the Respiration of White and Green Soybean Cells During Growth in Batch Suspension Culture

Abstract

In suspension cultures of white and green soybean cells (Glycine max L.) the capacity of the cytochrome pathway (Vcyt) and of the alternative pathway (Valt) together with the contribution of the alternative pathway (p · Valt) to total respiration have been determined during growth in batch culture. The capacity of the alternative pathway (Valt) and of the cytochrome (Vcyt) is comparable in white and green cells during growth. During the first four days of growth the contribution of the alternative pathway (p · Valt) in green cells is twice as much as that in white cells. This difference disappears at the end of the logarithmic growth phase. The reason why p · Valt in green cells is higher might be an enlarged demand for precursors in biosynthetic processes because of the presence of developing chloroplasts in green cells. When KCN is added in the absence of metal chelator, respiration of whole cells, but not of the isolated mitochondria, is stimulated. It is suggested that the enhancement of respiration by KCN is caused by stimulated glycolytic glucose catabolism. The affinity constants (1/Ki) for BHAM in presence of 0.1 µmol KCN in white and green cells during growth is found to be positively correlated to the capacity of the alternative pathway.