Feasibility to develop ultra-low nicotine tobacco leaf complying with proposed future nicotine regulation - a review of genetic approaches
One of the objectives of the WHO Framework Convention on Tobacco Control (FCTC) is to reduce the addictiveness of the tobacco product. To achieve this objective, the WHO Tobacco Regulation study group issued a recommendation to mandate a reduction in cigarette blend nicotine levels to 0.04 %. But is this technically feasible? Blend nicotine content could be significantly reduced using chemical nicotine extraction methods, however essential flavour compounds were also extracted resulting in poor quality tobacco. Cigarettes made using this process were met with low consumer acceptance and were a commercial failure. The focus is now on identifying genetic approaches to reduce nicotine content without affecting tobacco leaf quality. This review will examine the various genetic approaches being explored to reduce nicotine content, with respect to their ability to reduce nicotine and the effects on toxicant levels (e.g. TSNAs) and leaf quality (where such data is available). Some of these include the knockout or silencing of the main nicotine metabolic pathway genes, modulation of transcription factor regulatory genes, the application of non-coding RNAs, and transporter genes. Nicotine is known to affect the flavour amplitude and the impact of cigarette smoke. Complying with potential ultra-low cigarette blend nicotine ceilings creates a challenge for the tobacco industry to develop cigarettes that are acceptable to consumers.