Effect of Altitude on the Release of Metabolites in the Tobacco Rhizosphere Soil

Tobacco rhizosphere soils (area of Tujia and Miao Autonomous Prefecture of Hubei Province, China) of high (>1300 m), middle (800–1300 m), and low altitudes (<800 m) were collected to clarify the differences in metabolites in tobacco rhizosphere soil at different altitudes. Liquid chromatography-mass spectrometry (LC-MS/MS) was used to analyze the non-targeted metabolomics of tobacco rhizosphere soil metabolites. A total of 11 different metabolic substances were detected from the collected tobacco rhizosphere soil samples. Most differential metabolites were detected in tobacco rhizosphere soils at low and high altitudes. The levels of L-valine, pipecolic acid, and acetylcholine metabolites in tobacco rhizosphere soil at high altitudes were significantly increased. The levels of 1-aminocyclopropane carboxylic acid, L-proline, pyroglutamic acid, and naringenin metabolites in tobacco rhizosphere soil at low altitudes were significantly increased. At all altitudes, the differential metabolites in tobacco rhizosphere soil were significantly enriched in 10 synthetic pathways, wherein biosynthesis of secondary metabolites and amino acid biosynthesis were the main metabolic pathways. In conclusion, there are some significantly different metabolites in tobacco rhizosphere soil at different altitudes, which are mainly related to the biosynthesis of secondary metabolites and amino acids biosynthesis. The effects of these differential metabolites on tobacco growth and quality at different altitudes are worthy of further study.