Table 1 Top six discriminating wavenumbers, corresponding vibrational modes, and biochemical assignments for the first three LDs as indicated by individual loadings of tomato development (Wavenumber references: [17, 23, 33, 35,36,37])
PCA-LDA Loadings | Wavenumber (cm− 1) | Vibrational Mode | Biochemical Assignment |
|---|---|---|---|
LD1 | 1714 | ν(C=O· · ·H) ester ν(C=O) | Cutin Phenolic compounds, pectin |
1514 | ν(C-C) aromatic Amide II, ν(C=N), ν(C=C) | Phenolic compounds Proteins Lignin | |
1467 | δ(CH2) scissoring | Cutin, glycerolipids, wax hydrocarbons | |
1164 | νa(C-O-C) ester ν(C-OH), ν(C-O-C) | Cutin Polysaccharide, cellulose | |
1102 | νs(C-O-C) ester ν(C-O) νa(PO2) | Cutin Pectin, cellulose, carbohydrates Phosphate | |
1017 | ν(C-O), ν(C-C) ν(C-OH) | Pectin, cellulose Pectin | |
LD2 | 1732 | ν(C=O) ester ν(C=O) | Cutin, Lignin, wax, suberin-like aliphatic compounds |
1692 | ν(C=O· · ·H weak) ν(C=O· · ·H strong) | Cutin Cutin | |
1627 | ν(C=C) phenolic acid ν(C=O) Amide I | Phenolic compounds De-esterified pectin Proteins | |
1558 | ν(C=C) phenolic acid | Phenolic compounds Proteins | |
1522 | ν(C-C) aromatic Amide II, ν(C=N), ν(C=C) | Phenolic compounds Proteins Lignin | |
1106 | νs(C-O-C) ester ν(C-O) νa(PO2) | Cutin Cellulose, pectin, carbohydrates Phosphate | |
LD3 | 1725 | ν(C=O) ester | Cutin, pectin, phenolic compounds |
1698 | ν(C=O· · ·H strong) ν(C=O· · ·H weak) | Cutin Cutin | |
1511 | ν(C-C) aromatic | Phenolic compounds Lignin | |
1464 | δ(CH2) scissoring | Cutin, glycerolipids, wax hydrocarbons | |
1173 | νa(C-O-C) ester | Cutin | |
1106 | νs(C-O-C) ester ν(C-O) | Cutin Pectin, cellulose, carbohydrates |