Table 1.
Volume integration data of major lignin signals in HSQC spectra of wild-type (WT) and cad2 mutant culm cell wall and lignin samples.
| Lignin-enriched cell wallsa | Dioxane-soluble ligninsb | |||
|---|---|---|---|---|
| WT | cad2 | WT | cad2 | |
| Aromatic units | ||||
| H (p-Hydroxyphenyl units) (%)c | 5.0 ± 1.3 | 6.6 ± 0.9 | 2.0 | 2.9 |
| G (Guaiacyl units) (%)c | 45.1 ± 3.3 | 27.1 ± 3.0** | 49.4 | 30.7 |
| S (Syringyl units) (%)c | 43.9 ± 2.5 | 45.0 ± 2.3 | 44.7 | 47.9 |
| S′ (S units from sinapaldehyde) (%)c | n.d. | 2.0 ± 0.8* | n.d. | 2.5 |
| G′ (G units from coniferaldehyde) (%)c | 6.3 ± 1.6 | 19.2 ± 1.0** | 3.2 | 16.1 |
| S/G | 1.0 ± 0.1 | 1.7 ± 0.3* | 1.1 | 1.6 |
| (S + S′)/(G + G′) | 0.9 ± 0.1 | 1.0 ± 0.1 | 1.0 | 1.1 |
| T (Tricin units) (%)c | 14.3 ± 2.0 | 18.8 ± 2.4 | 24.1 | 43.3 |
| pCA (p-Coumarate units) (%)c | 89.7 ± 9.6 | 100.6 ± 12.5 | 91.6 | 102.4 |
| Inter-monomeric and end-group units | ||||
| I (β–O–4) (%)d | 85.3 ± 1.0 | 81.1 ± 1.6* | 82.7 | 80.6 |
| II (β–5) (%)d | 2.3 ± 0.5 | trace** | 5.5 | 0.9 |
| III + III′ (β–β) (%)d | 12.4 ± 0.7 | 18.7 ± 1.2** | 11.8 | 18.6 |
| I′ (8–O–4 from cinnamaldehydes) (%)d | n.d. | 7.9 ± 1.4* | n.d. | 18.9 |
| IV′′ (cinnamaldehyde end-units) (%) d | trace | 6.4 ± 2.6* | 0.8 | 13.5 |
| IV′′′ (benzaldehyde end-units) (%)d | trace | 2.0 ± 0.2** | trace | 2.2 |
aValues are means ± standard deviation (SD) for three individually analyzed plants. Asterisks indicate significant differences between WT and cad2 mutant plants (Student’s t-test, *p < 0.05; **p < 0.01). bValues are data collected for culm cell samples pooled from three biological replicates for each line. cExpressed as a percentage of the total of H, G, S, G′ and S′ aromatic signals. dExpressed as a percentage of the total of I, II, III, and III′ inter-monomeric linkage signals. For structure abbreviations and peak assignments, also see Fig. 3 and Tables S3 and S4. CWR, cell wall residue. n.d., not detected.