Growth and Respiratory Characteristics of Batch and Continuous Cell Suspension Cultures Derived from Fertile and Male Sterile Petunia hybrida

Growth rate of Petunia hybrida cells, cultivated in batch suspension was the same for cells derived from fertile (RMF) and male sterile (RMS) Petunia hybrida cv. Rosy Morn. The oxygen uptake by the RMS cells was twice that of the RMF cells. Analysis of the oxygen uptake data showed, that the capacity of both the mitochondrial cytochrome and alternative pathway was larger in the RMS cells; the non-mitochondrial residual respiration was about the same for both cell types (at least in the logarithmic and early stationary growth phase). The engagement of the alternative pathway in uninhibited respiration generally was low. When the dry weight production per mole of respiratory ATP was calculated, the RMS-cells had a much lower «growth efficiency« than the RMF cells, the latter forming about twice as much dry matter per mole of ATP. When these Petunia cells are cultivated in a Kurz airlift fermentor, at various glucose concentrations and at various dilution rates, the conversion of glucose in cellular dry weight appeared to be less efficient in RMS-cells (0.2 g dry weight produced per g of glucose) than in RMF-cells (0.4–0.5 g dry weight per g of glucose). Also for these continuously cultured cells, the respiration of the RMS-cells was higher and the dry weight production per mole of respiratory ATP was lower than for the RMF-cells, again indicating a more «efficient» growth for these RMF-cells. However, the absolute value of these parameters showed big differences for cells grown in batch and in continuous culture. The possible relation between the inefficient growth and respiration of the RMS-cells and the fact that the plants from which these cells were derived are cytoplasmic male sterile is discussed.