An amino-acid-grown maize cell line for use in investigating nitrate assimilation

Studies on uptake and assimilation of nitrate in plants are confounded by differences in cell function associated with anatomical features of roots as well as by problems inherent with growing plants without nitrate. To circumvent these problems, a Zea mays L. embryo cell line was grown in suspension culture using an amino-acid-based medium consisting of a Murashige and Skoog medium in which ammonium and nitrate were replaced by aspartic acid (100 mg/l), glycine (100 mg/l), arginine (150 mg/l), and glutamine (1 g/l). The growth, cellular characteristics, and physical appearance of the amino-acid-grown cells were similar to cells grown in the presence of nitrate. The amino-acid-grown cells exhibited the expected induction pattern and inhibitor sensitivity of nitrate uptake. This cell line should facilitate research on the induction of nitrate uptake and the regulation of nitrate assimilation into proteins.