Reducing the nitrate content of burley tobacco by grafting with flue-cured tobacco

Nitrosition of tobacco pyridine alkaloids by nitrate-derived NOx is the origin of tobacco specifc nitrosamines formed in tobacco, which are among the most notable toxicants present in tobacco products and smoke. Burley tobacco is particularly susceptible to TSNA formation because the cultivars exhibit a chloroplast deficient and nitrogen use defciency phenotype which results in high accumulation of nitrate. Strategies to lower nitrate levels in tobacco could produce a corresponding decrease in TSNAs accumulation in leaves. Previous studies have showed that grafting with high nitrogen use efficiency rootstock was able to improve the nitrogen utilization of flue-cured tobacco. In this study, a reciprocativel grafting experiment has been conducted with two varieties of different tobacco types to investigate whether replacing burley tobacco root with flue-cured tobacco by grafting can enhance pigment biosynthesis and photosynthesis parameters and reduce nitrate content of burley tobacco leaves, and to explore the corresponding mechanism.