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Effect of glycine nitrogen on lettuce growth under soilless culture: a metabolomics approach to identify the main changes occurred in plant primary and secondary metabolism
Author(s) -
Yang Xiao,
Feng Lei,
Zhao Li,
Liu Xiaosong,
Hassani Danial,
Huang Danfeng
Publication year - 2017
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.8482
Subject(s) - chemistry , ascorbic acid , glycine , amino acid , succinic acid , biochemistry , phenylalanine , fumaric acid , malic acid , glucoside , citric acid , chromatography , food science , medicine , alternative medicine , pathology
BACKGROUND Lettuce is a significant source of antioxidants and bioactive compounds. Nitrate is a cardinal fertilizer in horticulture and influences vegetable yield and quality; however, the negative effects of nitrate on the biosynthesis of flavonoids require further study. It is expected that using fertilizers containing organic nitrogen (N) could promote the synthesis of health‐promoting compounds. RESULTS Lettuces were hydroponically cultured in media containing 9 mmol L −1 nitrate or 9 mmol L −1 glycine for 4 weeks. Primary and secondary metabolites were analyzed using gas chromatography/mass spectrometry (GC/MS) and ultra‐performance liquid chromatography/ion mobility spectrometry/quadrupole time‐of‐flight mass spectrometry (UPLC/IMS/QTOF‐MS). Data analysis revealed that 29 metabolites were significantly altered between nitrate and glycine treatments. Metabolites were tentatively identified by comparison with online databases, literature and standards and using collision cross‐section values. Significant differences in flavonoid biosynthesis, phenolic biosynthesis and the tricarboxylic acid (TCA) cycle response were observed between N sources. Compared with nitrate, glycine promoted accumulation of glycosylated flavonoids (quercetin 3‐glucoside, quercetin 3‐(6″‐malonyl‐glucoside), luteolin 7‐glucuronide, luteolin 7‐glucoside), ascorbic acid and amino acids ( l ‐valine, l ‐leucine, l ‐glutamine, asparagine, l ‐serine, l ‐ornithine, 4‐aminobutanoic acid, l ‐phenylalanine) but reduced phenolic acids (dihydroxybenzoic acid hexose isomers 1 and 2, chicoric acid, chicoric acid isomer 1) and TCA intermediates (fumaric, malic, citric and succinic acids). CONCLUSION The novel methodology applied in this study can be used to characterize metabolites in lettuce. Accumulation of glycosylated flavonoids, amino acids and ascorbic acid in response to glycine supply provides strong evidence supporting the idea that using amino acids as an N source alters the nutritional value of vegetable crops. © 2017 Society of Chemical Industry