CLCNt2 Mediates Nitrate Content in Tobacco Leaf, Impacting the Production of Tobacco-Specific Nitrosamines in Cured Leaves.

Nitrate accumulation in tobacco ( L.) leaf, particularly in the burley (BU) type, is a reservoir for the generation of nitrosating agents responsible for the formation of tobacco-specific nitrosamines (TSNAs). TSNAs are mainly produced the nitrosation of alkaloids occurring during the curing of tobacco leaves.

Impairing both HMA4 homeologs is required for cadmium reduction in tobacco.

In tobacco, the heavy metal P1B-ATPases HMA4.1 and HMA4.2 function in root-to-shoot zinc and cadmium transport.

Expression of a constitutively active nitrate reductase variant in tobacco reduces tobacco-specific nitrosamine accumulation in cured leaves and cigarette smoke.

Burley tobaccos (Nicotiana tabacum) display a nitrogen-use-deficiency phenotype that is associated with the accumulation of high levels of nitrate within the leaf, a trait correlated with production of a class of compounds referred to as tobacco-specific nitrosamines (TSNAs). Two TSNA species, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN), have been shown to be strong carcinogens in numerous animal studies. We investigated the potential of molecular genetic strategies to lower nitrate levels in burley tobaccos by overexpressing genes encoding key enzymes of the nitrogen-assimilation pathway.