. 2017 May 19;12(5):e0177963. doi: 10.1371/journal.pone.0177963

Table 3. The concentrations of selected free amino acids (free AA; μmol/kg FW) in the above-ground biomass of plants.

Free AA	Treatment
	N. praecox	N. praecox-Cd	N. caerulescens	N. caerulescens-Cd
Ala	772^a ^A ± 2	652^b ^A ± 65	994^b ^B ± 39	805^a ^B ± 59
GABA	368^a ^A ± 6	382^a ^A ± 49	333^a ^A ± 39	392^a ^A ± 54
Phe	609^a ^B ± 31	625^a ^A ± 38	561^a ^A ± 39	770^b ^B ± 41
Tyr	625^a ^A ± 71	643^a ^A ± 68	599^a ^A ± 57	789^b ^B ± 39
Trp	714^a ^A ± 56	747^a ^A ± 42	630^a ^A ± 46	800^b ^A ± 57
Ile	137^a ^A ± 15	139^a ^A ± 11	120^a ^A ± 17	168^b ^A ± 19
Leu	560^a ^A ± 34	573^a ^A ± 38	537^a ^A ± 31	651^b ^A ± 41
Val	808^a ^B ± 75	728^a ^A ± 59	601^a ^A ± 54	568^a ^A ± 50
Gly	471^a ^A ± 42	446^a ^A ± 35	578^b ^B ± 41	449^a ^A ± 58
Orn	180^a ^A ± 1	312^b ^A ± 23	287^a ^B ± 25	336^a ^A ± 31
Thr	822^a ^A ± 9	875^a ^A ± 35	1440^a ^B ± 50	2348^b ^B ± 92

Free amino acid abbreviations: Ala, alanine; GABA, γ-aminobutyric acid; Phe, phenylalanine; Tyr, tyrosine; Trp, tryptophan; Ile, isoleucine; Leu, leucine; Val, valine; Gly, glycine; Orn, ornithine; Thr, threonine.

Treatment abbreviations: N. praecox, Noccaea praecox control plants without cadmium; N. praecox-Cd, Noccaea praecox plants with Cd solution in soil with a concentration of 90 mg Cd/kg of soil; N. caerulescens, Noccaea caerulescens control plants without cadmium; N. caerulescens-Cd, Noccaea caerulescens plants with Cd solution in soil with a concentration of 90 mg Cd/kg of soil.

The values represent the means of data obtained in the experiment (n = 5). Different letters indicate values that are significantly different (p < 0.05):

A, B comparison between the two species with the same treatment (growing with or without Cd solution applied to the tested soil)

a, b comparison between treatments in each species.