Reducing tobacco specific nitrosamines through alteration of the nitrate assimilation pathway
AssigneesPhilip Morris Products S.A., North Carolina State University
InventorsJianli Lu, Ramsey S. Lewis, Ralph Dewey, Lucien Bovet
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Abstract
Provided are modified tobacco plants having reduced nitrate levels and tobacco products generated from the modified tobacco plants having reduced tobacco specific nitrosamines (TSNAs). Also provided are methods of reducing TSNAs in tobacco products by altering the gene expression of the nitrate assimilation pathway
Claims25
A tobacco product having reduced tobacco specific nitrosamine (TSNA) levels which is generated from a tobacco plant, said tobacco plant being modified to comprise:
- (i) a polynucleotide comprising, consisting or consisting essentially of a sequence encoding a deregulated nitrate reductase enzyme;
- (ii) a polypeptide encoded by the polynucleotide set forth in (i);
- (iii) a polypeptide comprising, consisting or consisting essentially of a deregulated nitrate reductase enzyme;
- or
- (iv) a construct, vector or expression vector comprising the polynucleotide set forth in (i),
- wherein the expression or activity of said nitrate reductase is deregulated as compared to a control unmodified tobacco plant;
- and wherein the deregulated nitrate reductase enzyme comprises:
- (a) a nitrate reductase polypeptide comprising an amino acid substitution at a position corresponding to position 523 of SEQ ID NO:
- 4;
- or
- (b) a nitrate reductase polypeptide comprising an amino acid substitution at a position corresponding to position 523 of SEQ ID NO:
- 4, wherein the amino acid at position 523 of SEQ ID NO:
- 4 is substituted to an aspartic acid.
A tobacco product according to any preceding claim, wherein the polynucleotide encoding a deregulated nitrate reductase is a heterologous polynucleotide encoding a modified nitrate reductase polypeptide.
A tobacco product according to any preceding claim, wherein the polynucleotide encoding a deregulated nitrate reductase comprises a polynucleotide sequence of SEQ ID NO:
- 5.
A tobacco product according to any preceding claim, wherein the tobacco is a burley tobacco.
A tobacco product according to any preceding claim, having reduced tobacco specific nitrosamine (TSNA) levels compared to a tobacco product derived from a control tobacco plant in which the nitrate reductase enzyme has not been deregulated.
A tobacco product according to any one of the preceding claims, wherein the tobacco plant further comprises a modified nornicotine pathway gene.
A method for producing a tobacco product wherein TSNA levels measured in smoke obtained from combustion of leaves of a modified tobacco plant are reduced compared to TSNA levels measured in smoke obtained from combustion of an unmodified tobacco plant, comprising:
- (a) modifying a tobacco plant to comprise:
- (i) a polynucleotide comprising, consisting or consisting essentially of a sequence encoding a deregulated nitrate reductase enzyme;
- (ii) a polypeptide encoded by the polynucleotide set forth in (i);
- (iii) a polypeptide comprising, consisting or consisting essentially of a deregulated nitrate reductase enzyme;
- or
- (iv) a construct, vector or expression vector comprising the polynucleotide set forth in (i),
- wherein the expression or activity of said nitrate reductase is deregulated as compared to a control unmodified tobacco plant;
- and wherein the deregulated nitrate reductase enzyme comprises:
- (I) a nitrate reductase polypeptide comprising an amino acid substitution at a position corresponding to position 523 of SEQ ID NO:
- 4;
- or
- (II) a nitrate reductase polypeptide comprising an amino acid substitution at a position corresponding to position 523 of SEQ ID NO:
- 4, wherein the amino acid at position 523 of SEQ ID NO:
- 4 is substituted to an aspartic acid;
- (b) harvesting tobacco leaves from said modified tobacco plant;
- and
- (c) producing a tobacco product from the harvested leaves.
Dependencies are inferred from the claim text.