methods for reducing the level of nornicotine or n'-nitrosonornicotine in nicotiana plants and tobacco products, method for reducing the carcinogenic potential of tobacco products, isolated polynucleotide, isolated polypeptide, expression cassette, nicotiana plant, tobacco and method for identifying non-converting tobacco plants

摘要

METHODS TO REDUCE NORNICOTINE OR N'NITROSONORNICOTINE LEVEL IN NICOTIAN GENDER PLANTS AND TOBACCO PRODUCTS, METHOD TO REDUCE CARCINOGENIC TOBACCO PRODUCTS, ISOLATED POLYUCLEOTYLE, ISOLATED POLYUCLEOTE, ISOLATED POLYUCLEOTYTE, AND METHOD FOR IDENTIFYING NON-CONVERTING TOBACCO PLANTS. Compositions and methods for reducing the level of norncotine and N'-nitrosonornicotine (NNN) in Nicotiana plants and parts thereof are provided. The compositions comprise isolated P45O polynucleotides and polypeptides, which are involved in the metabolic conversion of nicotine to nornicotine in these plants. Also provided are expression cassettes, vectors, plants and parts thereof, comprising inhibitory sequences that direct the expression or function of the presented cytochrome P450 polypeptides. Also provided are methods for using these novel sequences to inhibit the expression or function of cytochrome P450 polypeptides involved in this metabolic conversion. The methods have application 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 passive aspiration derived from these products.