Phytohormone-induced GABA production in transformed root cultures of Datura stramonium: An in vivo <sup>15</sup>N NMR study
Ford YY., Ratcliffe RG., Robins RJ.
Primary nitrogen metabolism in transformed root cultures of Datura stramonium was observed by in vivo 15 N NMR. Treatment of the root cultures with the plant growth regulators α-naphthaleneacetic acid (NAA) and kinetin caused a de-differentiation of the root tissue, together with perturbation of primary and secondary nitrogen metabolism. The levels of newly-synthesized glutamine and glutamate during ammonium assimilation were depleted relative to control cultures, whereas GABA biosynthesis was enhanced. Although GABA production could be stimulated by a decrease in cytoplasmic pH (whether imposed artificially or induced by hypoxia), observation of the roots during phytohormone treatment by 31 P NMR showed that the cytoplasmic pH remained stable, indicating that the perturbation of nitrogen metabolism in the de-differentiated roots must be due to other causes.