Physiological Changes of Carrot Cells in Suspension Culture during Growth and Senescence

Abstract

Abstract Changes in the synthetic activities of nucleic acids and protein and in the amount of adenine nucleotides in Daucus carota cells have been examined during a period of rapid cell division and during the stationary phase. Cell growth and the syntheses of those macromolecules in the logarithmic phase were significantly enhanced by increasing the concentration of phosphate in the medium. In a phosphate‐rich medium, RNA and protein rapidly degraded and the number of cells with denatured cytoplasm increased when the culture entered into a stationary phase because of exhaustion of glucose. On the other hand, when the growth ceased by exhaustions of phosphate and nitrogen, the cells slowly underwent physiological changes leading to cellular senescence. The value of adenylate energy charge during the growth period was about 0.8–0.9 irrespective of the growth rate. After cessation of growth the value declined to about 0.5.