Basic Study on Material Metabolism of Flue-cured Tobacco Related to Maturity Based on Non-targeted Metabolomics
To clarify the quantitative indicators of fresh tobacco leaf maturity,Zhongyan 100 was used as the experimental material.Mid-stem leaves with SPAD values of 10-15(S10~15),15-20(S15~20),and 20-25(S20~25)were harvested to explore the metabolomics characteristics,as well as the appearance evaluation,physical properties,chemical composition,aroma content,and sensory quality of their post-cured leaves.The results showed that the post-cured leaves of the S15~20 treatment obtained the optimal quality,including better appearance quality,good physical properties,harmonious chemical components,and the highest total amount of neutral aromatic substances,showing high maturity.According to the partial least squares discriminant analysis(PLS-DA),32 mutual differential metabolites were identified between two comparison groups,including L-tryptophan,gamma aminobutyric acid,geranic acid,pyrrole-2-carboxylic acid,trehalose,kojibiose,nicotinate D-ribonucleoside,1-methyladenosine,sphinganine,melibiitol,indole,scopoletin,18-hydroxycorticosterone,25-hydroxycholesterol,and kaempferide,et al.These differential metabolites might be key differential metabolites during the maturation process of tobacco.Then,a total of 48 significantly differential metabolites were identified across the two groups,including 11 amino acids,7 steroids,6 organic acids,6 sugars,3 alcohols,3 nucleotides,2 flavonoids,1 vitamin,and 9 other metabolites.These significantly differential metabolites were primarily enriched in pathways such as amino acid biosynthesis,ABC transporters,arachidonic acid metabolism,lysine degradation,biosynthesis of phenylpropanoids,and butanoate metabolism,which might play important regulatory roles during the maturation of tobacco leaves.