List of metabolites in roots of cucumber seedlings whose relative fold changes were significantly down-accumulated (≤0.5) after Cd treatment and up-accumulated (≥1.5) or unchanged (0.5< and <1.5) after Cd + Se treatment.

Metabolite name	Similarity	R.T.a	Mass	VIPb	P valuec	Fold changed		Pathway
						Cd vs. control	Cd + Se vs. Cd
α-d-Glucosamine 1-phosphate	638	17.1326	226	1.63509	0.00164	—	0.50	Glycolysis
Glucose-6-phosphate 1	896	21.6314	387	1.39508	0.02454	—	0.57	Glycolysis
Glucose-6-phosphate 2	931	21.8916	387	1.23427	0.04055	—	0.60	Glycolysis
6-Phosphogluconic acid	670	22.5322	318	1.48791	0.00661	—	0.55	Glycolysis
Lactic acid	867	7.3366	219	1.88945	0.00009	0.36	4.09	TCA cycle
Ethanolamine	883	10.3063	86	1.51962	0.00503	—	0.76	Sugars and polyols
Ribose	931	15.4504	103	1.23105	0.03573	—	0.66	Sugars and polyols
Xylitol	804	15.6796	231	1.58847	0.00229	—	0.58	Sugars and polyols
Conduritol β epoxide 2	650	18.4594	220	1.52304	0.00415	—	0.58	Sugars and polyols
N-Acetyl-d-galactosamine 1	856	19.5938	87	1.61868	0.00126	—	0.57	Sugars and polyols
Ribulose-5-phosphate 1	758	19.9544	357	1.51388	0.00462	—	0.50	Sugars and polyols
Lactulose 1	832	24.6661	361	1.30364	0.03096	—	3.80	Sugars and polyols
Lactitol	707	25.3578	230	1.52403	0.00359	—	0.50	Sugars and polyols
Oxamic acid	566	10.1376	189	1.68048	0.00105	0.25	3.04	Amino acids
l-Homoserine 1	580	12.7268	218	1.07594	0.03957	0.09	5.21	Amino acids
Glycine 2	957	10.8446	174	1.84246	0.00034	0.59	2.17	Amino acids
Serine 1	953	11.5610	218	1.86332	0.00001	—	1.87	Amino acids
3-Hydroxy-palmitic acid	498	20.7420	299	1.22242	0.03691	—	0.63	Organic acids
O-Phosphorylethanolamine	914	16.6380	299	1.30504	0.02247	—	0.53	Organic acids
Succinate semialdehyde 1	292	9.1880	132	1.84506	0.00018	—	15.16	Lipids
2-Deoxyuridine	526	10.4501	170	1.16267	0.03924	—	0.52	Pyridine alkaloid
dl-Anabasine 1	632	12.1288	239	1.58278	0.00166	—	0.57	Pyridine alkaloid
Nicotinamide	467	13.4756	179	1.26266	0.03057	0.35	0.63	Pyridine alkaloid
Maleamate 2	449	13.8690	241	1.46397	0.00747	0.34	2.75	Pyridine alkaloid
2-Hydroxypyridine	908	7.0488	152	1.76756	0.00026	—	0.67	Pyridine alkaloid
N-Cyclohexylformamide 2	270	9.6684	227	1.61878	0.00111	—	0.66	Others

^aR.T. represents the retention time.

^bVIP = variable importance projection, metabolites (VIP > 1) are listed in the table.

^c P values were calculated according to Student's T-test.

^dFold change is represented as the ratio of the peak intensities for the corresponding treatments (n = 6), —: represented, not detected.