Article Figures & Data
Figures
- Figure 1.
GC-MS-based metabolomics. A, Analytical approach used. B, Conventional approach. C, Alternative, unbiased approach to GC-MS data analysis.
- Figure 2.
HCA of >20,000 molecular fragments based on their expression patterns throughout 198 GC-MS profiles. To simplify the view, only the highest branches of the dendrogram are displayed, showing the main groups of compounds as triangles. This procedure produced a dendrogram revealing a distinct cluster of nonplant components, comprising molecular fragments derived from constituents of the SPME fiber material that could then be readily removed from the dataset prior to further analysis.
- Figure 3.
Multivariate analyses of 94 tomato genotypes. A, Hierarchical tree of the 94 tomato genotypes based on intensity patterns of >20,000 individual molecular fragments. B, PCA plot showing two major types of differences between the tomato genotypes: between-type variation, discriminating the cherry tomatoes from round and beef tomatoes along vector 1, and within-type variation, independent of fruit type, along vector 2. C, PCA plot showing the distribution of >20,000 molecular fragments: Those molecular fragments (a) distributed along vector 1 determine the between-type variation, and molecular fragments (b) distributed along vector 2 determine the within-type variation. D, PCA plot showing the distribution of the identified volatile metabolites determining the main differences between the tomato genotypes. E and F, Two enlarged parts of the PCA plot shown in D: Compounds are shown as colored shapes and the numbers refer to the compounds presented in Table II. The smaller black dots represent unknown compounds.
- Figure 4.
MMSR-driven discrimination of mass spectra. A, Dendrogram showing a clustering of intensity patterns of ions situated in the retention time window 20.8 to 21.07 min into several molecular fragment clusters. B, MMSR indicated the presence of five individual compounds within a visually single total ion count (TIC) peak within the chosen time window. C-1, An experimental mass spectrum, obtained by plotting of the original intensities of the molecular fragments of compound b could be matched to the mass spectrum of the chemical standard analog of 2-isobutylthiazole (C-2), which also has a retention time falling within the chosen window.
- Figure 5.
Metabolite-metabolite correlation matrix of the 322 plant-derived compounds. A, The main compound clusters are situated along the diagonal line (groups a–g). Correlations between metabolites are shown in grayscale: the darker the color gray, the higher the percentage of similarity between metabolite expression patterns. B, Detailed dendrogram of each compound cluster with putative compound identity as described in Table II. Compound cluster: a, phenylpropanoid volatiles; b, other phenolic volatiles; c, Leu and Ile derivatives (c1 and c2, respectively); d, lipid derivatives. Isoprenoids: e, terpenoids; f, open-chain carotenoid derivatives; g, cyclic carotenoid derivatives.
Tables
- Table I.
Biological and analytical variation of the tomato volatile metabolites
For the analysis, a mix of tomato samples was made and separate aliquots were measured after 0, 4, 8, and 12 h. Using these four measurements, % sd (presented as the % of total value) was calculated for the sole use of CaCl2 (second column) and for the combination NaOH/EDTA + CaCl2 (third column). For the analysis of biological variation within genotype (fourth column), five individual fruits of the same genotype were profiled for volatiles, and % sd for these five replicates was calculated. Biological variation between genotypes (fifth column) was calculated as % sd of means of all 94 tomato samples when NaOH/EDTA + CaCl2 procedure was used. The maximal relative fruit-to-fruit variation as well as the maximal variation between all 94 genotypes was calculated as the ratio of maximal and minimal relative values of the 15 volatiles across the five fruits and the 94 genotype samples, respectively. It is given in parenthesis as fold difference (fourth and fifth columns).
Metabolites Analytical Variation, % sd Biological Variation within Genotype n=5, % sd Biological Variation between Genotypes n=94, % sd CaCl2 NaOH/EDTA + CaCl2 1-Penten-3-one 19 7 15 (1.4) 45 (6) 2-Isobutylthiazole 39 4 13 (1.4) 64 (47) 2-Methylbutanal 88 11 34 (2.7) 60 (16) 2-Methylbutanol 38 8 35 (2.5) 76 (39) 3-Methylbutanol 37 7 28 (2.2) 74 (29) 6-Methyl-5-hepten-2-one 33 4 17 (1.5) 37 (7) β-Ionone 51 17 10 (1.3) 62 (14) E-2-Heptenel 38 8 8 (1.2) 39 (10) E-2-Hexenal 34 5 25 (1.8) 37 (6) Hexanal 17 3 10 (1.3) 29 (8) Methyl salicylate 49 9 21 (1.6) 173 (656) Phenylacetaldehyde 42 6 23 (1.8) 162 (401) Phenylethanol 48 4 19 (1.5) 198 (686) Z-3-Hexenal 40 23 23 (1.7) 28 (7) Z-3-Hexenol 39 13 17 (1.5) 103 (28) Average 41 9 18 79 - Table II.
Putative identity of volatile metabolites present within the clusters obtained using HCA (Fig. 5)
Metabolites were identified by matching their mass spectra to the NIST library. RT, Retention time; specific ion (m/z), mass (m/z value) of a compound-specific molecular fragment; identity, putative identity, according to the highest NIST library match; NIST match, matching score (1,000 = 100% identical to the NIST library entry), (+) or (−) after the NIST match value (the NIST match was confirmed [+] or was not confirmed [−] by an authentic chemical standard injection); biochemical group, corresponding cluster in Figure 5.
Comp. No. Retention Time, min Specific Ion, m/z Identity NIST Match Biochemical Group 1 21.55 122 Salicylaldehyde 838 (+) a (corresponding to the clusters of Fig. 5) 2 23.06 81 Guaiacol 924 (+) a 3 26.89 120 Methyl salicylate 960 (+) a 4 29.32 120 Ethyl salicylate 951 a 5 31.90 164 Eugenol 920 (+) a 6 10.79 91 Toluene 953 b 7 14.45 91 Ethylbenzene 946 (+) b 8 15.61 104 Styrene 964 (+) b 9 18.05 91 1-Phenylpropane 934 b 10 18.34 106 Benzaldehyde 944 (+) b 11 18.55 94 Phenol 931 (+) b 12 19.11 118 p-Methylstyrene 705 b 13 19.24 103 Benzonitrile 841 (+) b 14 20.80 117 2-Phenyl-3-buten-ol 782 b 15 20.94 108 Benzyl alcohol 942 (+) b 16 21.43 120 Phenylacetaldehyde 950 (+) b 17 22.09 107 p-Cresol 951 (+) b 18 23.63 105 α-Phenylpropionaldehyde 862 b 19 23.95 91 Phenylethanol 944 (+) b 20 24.82 117 Phenylacetonitrile 856 (+) b 21 25.66 92 β-Phenylpropionaldehyde 876 (−) b 22 6.96 44 3-Methylbutanal 837 (+) c 23 7.21 57 2-Methylbutanal 887 (+) c 24 9.32 43 3-Methylbutanol 894 (+) c 25 9.50 57 2-Methylbutanol 922 (+) c 26 9.77 42 E-2-Methyl-2-butenal 922 c 27 12.77 60 3-Methylbutanoic acid 922 (+) c 28 15.85 41 3-Methylbutanol nitrite 835 (−) c 29 16.39 41 Unknown, C5H9NO2-like c 30 16.42 46 Unknown, C5H11NO2-like c 31 21.04 99 2-Izobutylthiazole 902 (+) c 32 7.67 57 1-Penten-3-ol 903 d 33 7.83 55 1-Penten-3-one 882 (+) d 34 8.18 44 n-Pentanal 883 (+) d 35 8.37 81 2-Ethylfuran 934 (+) d 36 10.20 55 E-2-Pentenal 926 d 37 10.51 42 1-Pentanol 895 (+) d 38 10.65 57 Z-2-Penten-1-ol 891 d 39 11.76 80 Z-3-Hexenal 847 (+) d 40 11.83 72 Hexanal 856 (+) d 41 13.60 41 2-Hexenal 904 d 42 13.90 98 E-2-Hexenal 944 (+) d 43 13.95 67 Z-3-Hexenol 899 (+) d 44 14.36 56 1-Hexenol 932 (+) d 45 15.75 70 Heptanal 898 (+) d 46 16.13 81 E,E-2,4-Hexadienal 938 (+) d 47 17.91 41 E-2-Heptenal 895 (+) d 48 19.26 81 2-n-Pentylfuran 925 d 49 19.44 81 E,E-2,4-Heptadienal 721 d 50 18.99 43 6-Methyl-5-hepten-2-one 919 (+) f 51 19.17 95 6-Methyl-5-hepten-2-ol 810 f 52 20.07 43 5-Hexen-2-one, 5-methyl-3-methylene 757 f 54 23.41 109 6-Methyl-3,5-heptadien-2-one 916 f 56 28.10 69 β-Citral 906 (+) f 57 28.98 41 α-Citral 941 (+) f 58 34.36 43 Geranyl acetone 904 (+) f 59 38.06 69 Pseudoionone 711 f 60 20.90 68 Limonene 621 (+) e 61 22.44 59 Linalool oxide, Z- 876 (+) e 62 22.99 59 Linalool oxide, E- 799 (+) e 63 24.91 93 Ocimenol 821 e 64 26.39 43 p-Cymen-8-ol 863 e 55 26.51 119 Acetophenone, 4-methyl 913 (+) e 65 26.69 59 α-Terpineol 889 (+) e 66 29.92 79 2-Caren-10-al 718 e 67 22.06 82 α-Isophorone 801 (−) g 53 22.32 105 Acetophenone 928 (+) g 68 27.80 152 β-Cyclocitral 878 (+) g 69 32.82 121 β-Damascenone 910 g 70 35.74 177 β-Ionone 851 (+) g
Supplemental Data
Supplemental Data
Files in this Data Supplement:
- Supplemental Data - Supplemental Data 1
- Supplemental Data - Supplemental Data 2
