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CORESTA Congress, New Orleans, 2002, AP 01

Frequency of nicotine conversion and its relationship to TSNA formation in air-cured tobacco varieties

NIELSEN M.T.; CUI M.; MIDGETT C.; OWEN J.K.
ProfiGen Inc., Winchester, KY, USA
Demethylation of nicotine to form nornicotine, or simply nicotine conversion, is a well-documented phenomenon in tobacco and is a subject of intense interest. Nicotine conversion is at least partly under genetic control and we developed segregating populations and evaluated foundation seed of a number of varieties to determine the relationship between nicotine conversion levels and formation of TSNA. A burley population segregating for nicotine conversion was used to generate plants with levels of nicotine conversion ranging from 3% to 100%, using ethylene-induced conversion followed by GC analyses. The same plants were then stalk-cut and air-cured to generate samples appropriate for TSNA analyses. In a companion study we screened foundation seed of 8 dark tobacco varieties for nicotine conversion and tracked individual plants through curing to provide material for TSNA analyses. The levels of conversion were much greater in the burley population than was observed in any of the dark tobacco varieties. Therefore, the variation in TSNA levels were also greater. In general the frequency of nicotine to nornicotine conversion was much less in dark tobacco than we have typically observed in burley and flue-cured tobacco varieties.