Nicotine genetic control

The genetic factors for anabasine formation are considered by Smith and Smith (279) to be partly dominant over those controlling nicotine formation in the Fi generation since the total percentage of anabasine was higher in the N. tabacum X N. glauca hybrid than in N. glauca. It is not considered dominant because the ratio of anabasine to total alkaloid is... 

The conversion of tryptophan to nicotinic acid in vivo is depicted in Figure 1. The rate of conversion of tryptophan to niacin and the pyridine nucleotides is controlled by the activities of tryptophan dioxygenase (known alternatively as tryptophan pyrrolase), kynurenine hydroxylase, and kynureninase. These enzymes are, in turn, dependent on factors such as other B vitamins, glucagon, glucocorticoid hormones, and estrogen metabolites, and there are various competing pathways which also affect the rate of conversion. For these reasons, a variety of nutrient deficiencies, toxins, genetic and metabolic abnormalities, etc. can influence niacin status and requirements. 

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