The Effects of Cytokinin Application on the Accumulation of Tobacco-specific Nitrosamines

The Council for Burley Tobacco funded this project in 2015; we are applying for a second year of funding because we would like to repeat it in 2016 so that we have two years of data. The 2015 crop is currently curing, so we do not yet have any data. An interim report was submitted in October. The goal of this study is to test whether spraying burley tobacco with the synthetic cytokinin benzyladenine is an efficient, cost-effective method for lowering TSNAs. Cytokinins increase nitrogen utilization and the antioxidative capacity of the plant, and can delay senescence. We hypothesize that short cytokinin treatments alter the nitrogen metabolism and cellular antioxidative capacity, possibly lowering TSNA accumulation. Results from a pilot study were promising: we found that the cytokinin application indeed lowered TSNA levels. We also found that the cytokinin concentration used does not delay senescence but instead promotes the senescence process, a potentially beneficial effect for the curing of tobacco leaves. This suggests that higher cytokinin concentrations could be used without causing any senescence delays. Now that we have proof of concept, we are planning tests to establish the most suitable application. This year, we propose to increase the cytokinin concentration to test whether this causes an even stronger suppression of TSNA formation without adversely affecting curing. If we can find an effective spray treatment, this will be the cheapest, simplest and most reliable way to reduce TSNAs.