Shikimate Pathway Activity during Shoot Initiation in Tobacco Callus Cultures

The activity of the shikimic acid pathway during shoot initiation in tobacco (Nicotiana tabacum L. Wisconsin 38) callus was examined. Enhancement of the activities of 3-deoxy-d-arabino-heptulosonic acid 7-phosphate synthase, shikimate kinase, chorismate mutase, and anthranilate synthase was observed during culture of tobacco callus under shootforming conditions in comparison to tissue cultured under non-organforming conditions. Confirmation of these findings was obtained by examining the incorporation of d-¹⁴C]glucose into quinic and shikimic acids and of ¹⁴C]shikimic acid into tyrosine, phenylalanine, and tryptophan.