HS-SPME-GC-MS-based untargeted metabolomics reveals the enhancement of pungent flavor quality in soilless-cultivated Chinese chives by preharvest application of methyl jasmonate

To improve the pungent flavor quality of soilless cultivated Chinese chives (Allium tuberosum Rottler), the effect of foliar spraying with methyl jasmonate (MeJA) was studied. Electronic nose analysis showed that 500 μM MeJA significantly promoted the accumulation of aromatic compounds and organic sulfides in soilless-cultivated Chinese chives, as well as the content of pungent flavor metabolites, such as enzymatic pyruvic acid (24.9%–69.9%) and the garlic odor compounds alliin (22.1%–51.4%) and methionine (8.0%–62.7%). Using the HS-SPME-GC-MS technique, fifteen species of 186 volatile metabolites were detected in Chinese chive leaves treated with MeJA, and the sulfur compounds were dominating between them (49.6%–61.7%). Metabolomics and chemometrics analysis identified the volatile biomarkers of MeJA-treated substrate culture and hydroponic Chinese chives as dimethyl disulfide, dimethyl tetrasulfide, diallyl disulphide and allyl methyl sulfide, and methyl 2- propenyl disulfide, dimethyl tetrasulfide compound, respectively. Orthogonal partial least squares discriminant analysis indicated that MeJA treatment enhanced the pungency of Allium tuberosum mainly by increasing the accumulation of dimethyl sulfide and allyl sulfide compounds. Current study provides theoretical and technical basis for improving the pungent flavor quality of soilless-cultivated Chinese chives.