Metabolomic Analysis of Metabolic Differences and Formation Mechanisms in Open Fire-cured Tobacco Leaves

Purpose To analyze the metabolic differences and formation mechanisms in open fire-cured tobacco leaves by metabolomics techniques.

Methods Tobacco cultivar K326 was used as the test material for a comparative study between open fire-curing (X) and conventional curing (CK). Metabolomic techniques were employed to analyze the metabolic differences between the two curing methods and to explore their formation mechanisms.

Results KEGG enrichment results indicated that: in the X-38 vs CK-38 comparison groups, linoleic acid metabolism and plant hormone signal transduction were the two most significantly enriched pathways; in the X-42 vs CK-42 comparison groups, glycolysis/gluconeogenesis and amino acid biosynthesis were the two most significantly enriched pathways; in the CK-42 vs CK-38 and X-42 vs X-38 comparison groups, linoleic acid metabolism and nucleotide metabolism were the two most significantly enriched pathways. The up-regulated metabolites in all four comparison groups included free fatty acids, amino acids and their derivatives, phenolic acids, sugars, organic acids, alkaloids, nucleotides and their derivatives.

Conclusion The differential metabolites in open fire-cured tobacco leaves include a large number of acidic metabolites. The formation of these differences is due to additional environmental stresses such as smoke and thermal radiation experienced during open fire-curing, which lead to the production of more metabolites in open fire-cured tobacco leaves.