Differential metabolic networks in three energy substances of flaxseed (Linum usitatissimum L.) during germination.

• The metabolic pathway networks of three energy substances in flaxseed germination were proposed. • Arginine and Proline metabolism were the key pathways in flaxseed during germination. • During flaxseed germination, arginine was the most active metabolite. • Sucrose partakes in galactose metabolism and starch and sucrose metabolism. • The main phospholipid molecules in the flaxseed were PA, PE, LPA, and LPC at 0–7 d. Germinated flaxseed (Linum usitatissimum L.) is an essential potential food ingredient, but the major energy substances (proteins, lipids, and carbohydrates) metabolites and metabolic pathways are unknown. Comprehensive metabolomic analyses were performed using Fourier transform infrared spectroscopy and high-performance liquid chromatography mass spectrometry on flaxseed from 0 to 7 d. Additionally, the critical metabolites pathways networks of three energy substances metabolites during flaxseed germination were exhibited. The results showed that arginine was the most active metabolite during germination, strongly associated with the arginine biosynthesis and arginine and proline metabolism pathways. Carbohydrates predominantly comprised sucrose on 0–3 d, which participated in galactose metabolism and starch and sucrose metabolism. The main flaxseed phospholipid molecules were phosphatidic acid, phosphatidylethanolamine, lysophosphatidic acid, and lysophosphatidylcholine during germination. This study underscores the paramount metabolic pathways in proteins, lipids and carbohydrates were arginine and proline metabolism, linoleic acid metabolism, arachidonic acid metabolism, and ascorbate and aldarate metabolism during germination. [ABSTRACT FROM AUTHOR]