Factors Affecting Alkaloid Formation

A number of factors have been studied for their influence on nicotine production. Of these the negative effect of auxins, and in particular 2,4-D, on alkaloid production is worth mentioning (202-204,211,220, 225,226,229,255). In root cultures the addition of indoleacetic acid (lAA) also reduces alkaloid production (196). Light was reported to inhibit nicotine formation (50,255). In a green cell suspension, however, increased nicotine levels were found on illumination (229). Ikemeyer and Barz (243) reported that a photoautotrophic cell line of N. tabacum did not produce nicotine, whereas a heterotrophic cell line did accumulate this alkaloid. Elicitation with a preparation of the fungus Phytophthora megasperma did not affect the nicotine levels of these cell lines. Addition of organic acids to the medium resulted in increased alkaloid formation in callus cultures (up to 3.25%) (230). For a review of the various cultural factors which influence secondary metabolism, the reader is referred to Mantell and Smith (255). 

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