Glutamic acid-induced shoot differentiation in tobacco callus tissues and changes in nicotine content and in activities of aminotransferases, ornithine transcarbamylase, and arginase.

Floral bud calluses of Nicotiana tabacum L. var. Anand-2 produced multiple shoots on Murashige and Skoog's (MS) medium supplemented with 2 mg/l indole-3-acetic acid (IAA), 0.4 mg/l kinetin (Kn), and L-glutamic acid (2.5 mM). However cultures of calluses on MS medium containing only the IAA and Kn did not differentiate shoots. Specific activities of phenylalanine aminotransferase, tyrosine aminotransferase, and ornithine aminotransferase were over 7-, 5- and 5-fold higher, respectively, in the glutamic acid-treated calluses than in the nonshoot-forming ones on the day of shoot emergence. Activities of ornithine transcarbamylase and arginase decreased after the onset of the differentiation process. Implications of the enzyme activities in the differentiation process and in nicotine biogenesis are discussed.