Feng Y, Zhao Y, Li G, Shi H. Reducing nitrate and tobacco-specific nitrosamine level in burley tobacco leaves through grafting on flue-cured tobacco rootstock.
PLANT DIRECT 2023;
7:e536. [PMID:
37841064 PMCID:
PMC10568975 DOI:
10.1002/pld3.536]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 08/31/2023] [Accepted: 09/20/2023] [Indexed: 10/17/2023]
Abstract
Nitrosation of pyridine alkaloids in tobacco generates tobacco-specific nitrosamines (TSNAs), which are notable toxicants in tobacco products and smoke. Burley tobacco, a chloroplast- and nitrogen (N)-deficient phenotype that accumulates high levels of nitrate-nitrogen (NO3-N) in its leaves, is particularly susceptible to TSNAs formation. In this study, reciprocal pot and field grafting experiments were conducted using burley tobacco Eyan No.1 and flue-cured tobacco K326 to investigate whether grafting burley tobacco scions on flue-cured tobacco rootstocks could enhance pigment biosynthesis and photosynthesis, while reducing the NO3-N level in burley tobacco leaves. Grafting burley tobacco scions on flue-cured tobacco rootstocks significantly increased the total pigment content, photosynthetic rate, biomass, nitrate reductase and glutamine synthetase activities, as well as ammonium-nitrogen (NH4-N), total soluble and reducing sugar, and soluble protein levels in burley tobacco leaves compared with burley tobacco self-rooting, while decreasing the NO3-N level and nitrate-N to total N ratio. Transcriptomic analysis revealed that grafting resulted in upregulated expression of genes involved in starch, sucrose, porphyrin, chlorophyll, and N metabolism, as well as carbon fixation and carotenoid biosynthesis. The findings suggest that grafting on high N use efficiency rootstock is an exceptionally promising means of decreasing NO3-N accumulation by improving photosynthesis and N metabolism in the scion, thereby reducing the levels of harmful TSNAs.
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