Studies on the Growth in Culture of Plant Cells

Abstract

The responses of steady-state cell populations of Acer pseudoplatanus L. (sycamore) in chemo-stats to changes in the nitrate concentration of their environment was generally predictable by equations derived for ideal, free-cell, nitrate-limited populations. A step-down in nitrate concentration in the input medium of a chemostat produced interlocking oscillations in spent-medium nitrate, intracellular pools of nitrate and amino-N, protein accumulation, and cell division. The rate of nitrate uptake into the cell and thus the flow of nitrogen into protein (and ultimately the specific growth rate) was seen to be finely regulated by spent-medium nitrate concentration. Steady states of growth of sycamore cells were established with glucose as the limiting nutrient both from inoculation and after switching from nitrate to glucose limitation. Glucose-limited cells produced by glucose step-down of a nitrate-limited population suffered major losses of cell material, including starch and cell wall polysaccharide, to the extent that protein then accounted for c. 70% of cell dry weight.