| Abstract: | Nitrate transport characteristics of an amino acid-grown Zeamays P3377 cell culture line were studied. Age (days after subculturing)of the cells was shown to have a significant effect on  transport; older stationary phasecultures did not absorb nitrate from the medium as rapidly asyounger growing cultures. Solution composition had a pronouncedimpact on induction of accelerated nitrate transport and transportrates. Maximum uptake rates required fresh culture media ratherthan simple solutions. Differences in ionic strength among uptakesolutions of equal concentration were shown to affect the apparent uptake rates by changing theactivity coefficient of . The uptake kinetics were established by following uptake for 24h in a wide range of nitrate concentrations. Uptake patternsof cells in solutions ranging from 0.02 to 2 mM were as typicallyreported for plants. The kinetic constants for the Zea mayscell suspension cultures concurred with reports of other solution-culturedcells. When cells were placed in solutions containing greater than 2 mM, uptake patternssuggested a significant passive uptake component. Passive diffusionof was estimated by Nernst analysis and indicated to be an important component of nitrateuptake in maize cell suspension cultures grown in the absenceof nitrate then transferred into nitrate-containing media. Key words: Cell suspension culture, nitrate, passive uptake, Zea mays |
