Metabolomics Reveals the Effects of Lighting Time on the Growth and Development of Flue-Cured Tobacco.

Lighting time plays an important role in the yield and quality of flue-cured tobacco (Nicotiana tabacum L.). This study aimed to explore the effects of different lighting time on flue-cured tobacco quality at a metabolomics level. Pot experiments were used to breed long-day and short-day flue-cured tobacco. The long-day and short-day tobacco plants were treated with 16 h sunlight/8 h dark and 8 h sunlight/16 h dark, respectively. Thereafter, the leaves of the long-day and short-day tobacco were collected for liquid chromatography-mass spectrometry and metabolomics analysis. At phenotype level, the growth process of the long-day tobacco plant was faster (more yellow leaves); whereas the short-day tobacco plant manifested delayed nitrogen metabolism and slow maturation. After metabolomics analysis, a total of 92 differential metabolites (4 up-regulated and 88 down-regulated) were identified between the long-day and short-day tobacco, including amino acids, organic acids, saccharides, and pyrimidines. Functional analyses showed that these differential metabolites were significantly enriched in 14 KEGG pathways, including "metabolic pathways", "pyrimidine metabolism", "phenylalanine metabolism", and "phenylpropanoid biosynthesis". Our work reveals the key metabolites in tobacco plants with different lighting time, and lighting time can regulate metabolic pathways, phenylpropanoid biosynthesis, pyrimidine metabolism, amino acid-related pathways and nicotinic acid-derived alkaloids biosynthesis, thereby affecting tobacco plant growth and development, and the quality of flue-cured tobacco. [ABSTRACT FROM AUTHOR]