A Metabolomic Analysis of Tomato Fruits in Response to Salt Stress

Salt stress affects all stages of tomato growth and development, reducing tomato yield, but moderate salt stress improves tomato quality. To gain a deeper understanding of the effect of salt stress on tomato fruits, a widely targeted metabolomic method based on ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) was used to analyze tomato fruits under three different soil salt contents (CK: 0.05 g·kg−1; MS: 3 g·kg−1; and HS: 6 g·kg−1). A total of 847 metabolites were detected in tomato fruit under salt stress, including six primary metabolites such as lipids, amino acids and their derivatives, sugars, nucleotides and their derivatives, and organic acids, and nine secondary metabolites such as phenolic acids, alkaloids, and flavonoids. There were 54 different metabolites in the three treatments, mainly flavonols and phenolamines. Dopamine, galactotol, and mannitol were not detected in the control group, but their contents were higher in the salt treatment. KEGG analysis showed that the differential metabolites were mainly concentrated in flavonoid biosynthesis, betaine metabolism, sulfur metabolism, and galactose metabolism. This study provides a theoretical basis for the regulation of tomato quality through salt stress.