Alteration of tobacco alkaloid content through modification of specific cytochrome P450 genes

摘要

Compositions and methods for reducing the level of nornicotine and N′-nitrosonornicotine (NNN) in Nicotiana plants and plant parts thereof are provided. The compositions comprise isolated polynucleotides and polypeptides for cytochrome P450s that are involved in the metabolic conversion of nicotine to nornicotine in these plants. Expression cassettes, vectors, plants, and plant parts thereof comprising inhibitory sequences that target expression or function of the disclosed cytochrome P450 polypeptides are also provided. Methods for the use of these novel sequences to inhibit expression or function of cytochrome P450 polypeptides involved in this metabolic conversion are also provided. The methods find use in the production of tobacco products that have reduced levels of nornicotine and its carcinogenic metabolite, NNN, and thus reduced carcinogenic potential for individuals consuming these tobacco products or exposed to secondary smoke derived from these products.

主权项

1. Cured tobacco material or a tobacco product comprising said cured tobacco material, wherein said cured tobacco material is made from a tobacco plant comprising a stable mutation in a wild type allele encoding a nicotine demethylase having an amino acid sequence of SEQ ID NO:4 or a sequence having 98% identity to SEQ ID NO:4, wherein said mutation reduces or eliminates the expression or activity of said nicotine demethylase, wherein the amount of nornicotine or N-nitrosonornicotine in said cured tobacco material is reduced by greater than about 10% compared to cured tobacco material made from a control tobacco plant comprising said wild type allele; and wherein said tobacco plant is a Nicotiana tabacum plant.