Tobacco with Reduced Nornicotine by Targeted Mutation

Secondary alkaloid derivatives in tobacco, like nicotine and its conversion product nornicotine, has been implicated in increased risks for hypertension, bronchitis, emphysema and lung cancer among other respiratory pathologies. Nornicotine, specifically, was found to cause detrimental metabolic diseases by triggering aberrant protein glycation, a haphazard process that impairs the functioning of biomolecules.

Numerous studies have been aimed to reduce the nornicotine content of tobacco. The identification of the nicotine N-demethylase function of the enzyme cytochrome P450, responsible for nicotine to nornicotine conversion, allowed the reduction of nornicotine in cultivated tobacco using biotechnological and mutation approaches.

By exposing the plants to the chemical mutagen EMS, a group of French scientists obtained tobacco harboring nonsense and missense mutations (resulting to proteins with incorrect amino acid composition) of  the cytochrome P450 gene. The mutants obtained have very low to negligible nornicotine content. Backcrossing the mutants with an elite variety expressing reduced nornicotine (obtained in another study using traditional breeding) produced plants that are phenotypically identical to the parents. The low-nornicotine varieties obtained are therefore non-genetically modified, as it resulted from a combination of mutation and traditional breeding.

Read the abstract at http://www.springerlink.com/content/p27478383201273r/?p=c2a281059332474ba8c5ef260c80f8a7&pi=0 or the full paper at http://www.springerlink.com/content/p27478383201273r/fulltext.pdf