Table II. Amino acids and ammonium determined by UPLC.

Data (µmol g⁻¹ fresh weight) indicate means ± sd (n = 3). Compounds were assigned to biosynthesis pathways according to Ehlting et al. (2007). Statistical significances between early-spring and summer samples were analyzed by a paired Student’s t test. P values were adjusted by the Benjamini-Hochberg method. AABA, α-Aminobutyric acid; GABA, γ-aminobutyric acid. n.d. = not detected.

Biosynthesis Pathway	Compound	Early Spring	Summer	P Value	Adjusted P Value
Asp group	l-Asp	0.16 ± 0.010	0.23 ± 0.050	0.079	0.105
	l-Thr	n.d.	0.03 ± 0.010	n.d.	n.d.
	l-Lys	0.03 ± 0.002	n.d.	n.d.	n.d.
Glu group	l-Gln	0.05 ± 0.010	0.41 ± 0.210	0.040	0.064
	l-Arg	3.9 ± 1.290	n.d.	n.d.	n.d.
	l-Glu	0.17 ± 0.010	0.28 ± 0.050	0.021	0.042
	GABA	0.05 ± 0.016	0.25 ± 0.010	8.78E-05	7.02E-04
	AABA	0.01 ± 0.004	n.d.	n.d.	n.d.
Pyruvate group	l-Ala	0.03 ± 0.010	0.03 ± 0.010	0.803	0.803
Ser group	l-Ser	n.d.	0.11 ± 0.020	n.d.	n.d.
	Gly	n.d.	0.02 ± 0.001	n.d.	n.d.
Shikimate group	l-Phe	0.03 ± 0.003	n.d.	n.d.	n.d.
Others	Ammonium	0.12 ± 0.040	0.08 ± 0.040	0.344	0.393
	Ethanolamine	0.14 ± 0.020	0.07 ± 0.003	0.001	0.004
Total		4.83 ± 1.320	1.56 ± 0.30	0.014	0.037