Table 2 Effects of N supply on mean (±SE, n = 3) concentrations (μg g⁻¹ DW) of FAADs as well as their summation in Citrus sinensis roots

NAT

C₁₁H₁₃NO₄

0.165±0.001b

0.340±0.022a

0.323±0.017a

0.408±0.035a

0.403±0.051a

H-Tyr-OMe

C₁₀H₁₄NO₃

0.199±0.016a

0.080±0.005c

0.122±0.026bc

0.148±0.025ab

0.147±0.017ab

KYNA

C₁₀H₇NO₃

0.233±0.010a

0.291±0.030a

0.269±0.016a

0.273±0.024a

0.231±0.015a

Phe

C₉H₁₁NO₂

2.154±0.065b

2.291±0.189b

3.145±0.323a

3.633±0.318a

3.782±0.268a

Tyr

C₉H₁₁NO₃

31.199±1.428b

73.209±4.578a

83.615±3.571a

78.660±6.685a

70.230±6.440a

α-AP

C₁₃H₁₆N₂O₅

1.566±0.040b

2.192±0.084a

2.443±0.094a

2.540±0.155a

2.221±0.192a

Leu

C₆H₁₃NO₂

5.354±0.425b

6.832±0.324a

7.747±0.531a

7.650±0.540a

6.968±0.405a

Ile

C₆H₁₃NO₂

8.767±0.782c

17.868±0.948ab

17.952±1.152a

16.048±1.230ab

14.522±1.160b

L-Pipecolic acid

C₆H₁₁NO₂

29.837±5.389c

95.538±12.080b

154.734±9.567a

189.444±8.235a

206.392±34.005a

NAA

C₆H₉NO₅

0.284±0.048c

1.352±0.090bc

1.762±0.420ab

2.675±0.327a

2.347±0.651ab

α-Aminoadipic acid

C₆H₁₁NO₄

73.208±4.056a

25.016±3.301b

18.591±1.362bc

14.702±0.925c

14.432±1.486c

4-Acetamidobutyric acid

C₆H₁₁NO₃

0.688±0.044a

0.701±0.009a

0.653±0.046a

0.645±0.038a

0.597±0.048a

ACA

C₆H₁₃NO₂

1.236±0.018c

1.923±0.033a

1.626±0.060b

1.600±0.068b

1.501±0.056b

Trp

C₁₁H₁₂N₂O₂

71.085±5.983a

71.149±3.780a

66.691±3.888a

71.457±3.302a

67.582±5.361a

Glycylphenylalanine

C₁₁H₁₄N₂O₃

0.409±0.024c

0.531±0.009a

0.547±0.008a

0.547±0.018a

0.463±0.014b

N'-Formylkynurenine

C₁₁H₁₂N₂O₄

4.974±0.554c

7.231±0.074b

8.085±0.116ab

9.054±0.503a

9.036±0.643a

Val

C₅H₁₁NO₂

18.698±1.565c

27.613±1.391a

24.994±0.985ab

23.315±1.307b

22.661±1.051bc

Met

C₅H₁₁NO₂S

3.743±0.085c

7.003±0.195a

7.059±0.337a

5.983±0.452b

6.210±0.184ab

Pro

C₅H₉NO₂

374.028±22.621c

1492.480±27.103b

1928.221±122.469a

2048.379±127.600a

1980.211±6.484a

Glu

C₅H₉NO₄

4882.527±168.286b

6279.027±253.890a

6550.942±263.117a

6795.105±94.542a

6721.240±73.946a

5-HTP

C₁₀H₁₂N₂O

36.506±1.836a

26.402±2.582c

27.071±0.638bc

31.948±2.034abc

33.912±3.297ab

Trans-4-Hydroxy-L-proline

C₅H₉NO₃

3.819±0.585c

37.349±0.798b

49.452±3.473a

51.573±4.419a

48.613±5.078a

MetSO

C₅H₁₁NO₃S

2.174±0.054c

4.281±0.304a

4.090±0.078a

3.867±0.198ab

3.474±0.174b

5-Aminovaleric acid

NH₂(CH₂)₄CO₂H

1.944±0.079c

2.197±0.018bc

2.483±0.106ab

2.651±0.142a

2.596±0.249ab

Asp

C₄H₇NO₄

421.848±45.155c

825.214±30.502a

716.624±44.105b

876.584±14.487a

897.974±23.794a

Thr

C₄H₉NO₃

59.546±1.176c

117.639±8.039b

142.318±7.715a

139.047±8.561ab

132.957±9.415ab

Homoserine

C₄H₉NO₃

1.742±0.043b

6.916±1.022a

7.793±1.188a

8.486±0.119a

6.889±2.227a

N6-Acetyl-L-lysine

C₈H₁₆N₂O₃

1.641±0.038b

3.397±0.230a

3.171±0.365a

3.038±0.316a

2.777±0.434a

(5-L-Glutamyl)-L-amino acid

C₈H₁₄N₂O₅S

7.225±0.319c

24.528±1.782ab

29.969±2.840a

25.353±1.698ab

22.180±2.472b

N-Glycyl-L-leucine

C₈H₁₆N₂O₃

1.056±0.082c

1.389±0.105b

1.697±0.032a

1.770±0.113a

1.339±0.065b

γ-Glutamate-cysteine

C₈H₁₄N₂O₅S

ND

72.421±6.540a

65.085±9.579a

46.665±19.215a

62.097±13.921a

2-Aminobutyric acid

C₄H₉NO

0.605±0.035b

1.107±0.133a

1.014±0.124a

1.042±0.168a

0.937±0.133ab

(S)-β-Aminoisobutyric acid

C₄H₉NO

1.799±0.134b

3.215±0.202a

3.536±0.477a

3.578±0.426a

3.343±0.496a

GABA

C₄H₉NO

885.850±23.997b

3313.895±27.368a

3594.377±395.769a

3791.500±258.905a

3257.049±294.992a

DMG

C₄H₉NO₂

0.152±0.076b

0.430±0.036a

0.426±0.069a

0.431±0.035a

0.382±0.036a

LCYH

C₇H₁₄N₂O₄S

19.039±2.350a

5.215±0.392b

7.133±0.294b

8.231±1.228b

8.069±0.584b

GLY-PRO

C₇H₁₂N₂O₃

0.745±0.005d

1.280±0.050c

1.762±0.114ab

1.973±0.110a

1.596±0.070b

NAG

C₇H₁₂N₂O₄

1.657±0.104b

2.077±0.186b

4.511±0.529a

4.525±0.808a

5.491±0.589a

GSSG

C₂₀H₃₂N₆O₁₂S₂

8291.753±901.041c

28363.315±2223.965b

39540.366±2348.517a

44467.728±7029.281a

41518.728±1469.166a

Ala

C₃H₇NO₂

169.976±7.362c

414.387±32.296b

589.784±32.025a

508.838±40.846ab

437.666±59.094b

Ser

C₃H₇NO₃

92.352±1.495c

306.843±13.234b

382.944±32.603a

375.183±20.996ab

365.122±27.631ab

Lys

C₆H₁₄N₂O₂

54.745±3.990d

272.506±14.334c

443.637±45.060b

439.929±47.889ab

447.527±26.121a

β-Ala

C₃H₇NO₂

44.684±3.817b

321.239±13.730a

429.385±53.519a

419.892±45.015a

383.111±59.216a

TMAO

C₃H₁₃NO₃

0.00919±0.00018a

0.00590±0.00038b

0.00276±0.00017c

0.00273±0.00006c

0.00256±0.00002c

N8AS

C₉H₂₁N₃O

2.745±0.162b

4.203±0.250a

4.331±0.010a

4.671±0.203a

4.472±0.176a

D-Ala-D-Ala

C₆H₁₂N₂O₃

11.662±0.236c

26.255±0.886a

22.260±2.114a

17.498±1.604b

13.289±0.954c

Cys

C₃H₇NO₂S

ND

2.185±1.148a

3.799±0.230a

ND

ND

Hyl

C₆H₁₄N₂O₃

ND

3.752±0.021b

4.376±0.088a

4.708±0.216a

4.688±0.222a

Gln

C₅H₁₀N₂O₃

1660.744±97.980c

2470.030±94.279c

3775.858±77.545b

4729.450±445.431a

5471.375±327.451a

Orn

C₅H₁₂N₂O₂

20.165±1.102d

62.994±4.976c

162.107±19.792b

177.968±30.235ab

210.096±16.232a

ASA

C₁₀H₂₀N₄O₆

38.332±0.776a

9.740±0.267c

13.256±1.147b

14.199±0.706b

13.821±0.493b

HC

C₇H₁₅N₃O₃

0.734±0.011c

0.822±0.015b

0.926±0.044a

0.869±0.012ab

0.880±0.030ab

3-N-Methyl-L-His

C₇H₁₁N₃O₂

4.067±0.184a

3.805±0.259a

3.697±0.237a

3.717±0.130a

3.641±0.196a

S-(5-Adenosy)-L-homocysteine

C₁₄H₂₀N₆O₅S

6.063±0.054b

16.725±0.436a

15.887±0.955a

15.472±0.872a

15.785±1.463a

L-Carnosine

C₉H₁₄N₄O₃

2.018±0.028c

2.787±0.170b

3.324±0.101a

3.245±0.104a

2.798±0.041b

Asn

C₄H₈N₂O₃

793.707±45.995d

3076.171±270.464c

5167.251±144.278b

5887.175±388.061ab

6316.118±145.607a

Cit

C₆H₁₃N₃O₃

18.431±2.632d

107.488±3.100c

210.235±17.070b

234.994±31.482ab

275.774±6.540a

Gly

C₂H₅NO₂

13.987±1.395c

59.992±1.186b

84.196±8.524a

88.209±5.087a

88.209±5.087a

Nα-Acetyl-L-arginine

C₈H₁₆N₄O₃

5.953±0.588a

5.235±0.228a

5.813±0.325a

5.364±0.261a

4.900±0.776a

2-Aminoethanesulfonic acid

C₂H₇NO₃S

1.804±0.031b

1.804±0.031b

3.559±0.434a

3.647±0.361a

3.616±0.240a

EtA

C₂H₇NO

34.798±2.553c

85.061±5.648a

81.762±2.640a

69.332±12.292ab

61.569±2.705b

Homo-Arg

C₇H₁₆N₄O₂

9.273±0.102d

11.952±0.515c

15.939±1.399b

16.224±0.356ab

17.929±1.918a

3,7-Dimethyluric acid

C₇H₈N₄O₃

ND

ND

ND

ND

ND

Arg

C₆H₁₄N₄O₂

291.375±14.853c

474.445±8.089b

906.772±30.635a

967.224±88.045a

1054.664±63.417a

CP

C₄H₈N₃Na₂O₅P

73.734±5.552b

146.347±31.718a

123.320±18.966ab

164.386±10.906a

155.567±8.084a

Creatine

C₄H₉N₃O₂

0.104±0.104a

0.163±0.163a

0.154±0.154a

0.370±0.013a

0.375±0.020a

Succinic acid

C₄H₆O₄

691.983±50.826c

1770.347±76.789a

1542.250±34.615ab

1570.586±90.656ab

1394.339±134.070b

TFAADs

19292.898±1188.472c

50582.832±3001.737b

67070.472±3239.715a

74465.409±7887.679a

71882.835±1558.005a