Table 1.
Cell features in the different histological zones of the SAM
| CZ | PZ | RZ | P1 | |
|---|---|---|---|---|
| Cell surface area (μm2) | 213·54 ± 61·68 | 135·15 ± 28·06 | 209·25 ± 56·79 | 155·76 ± 34·04 |
| Cell circularity | 0·81 ± 0·07 | 0·81 ± 0·05 | 0·82 ± 0·07 | 0·78 ± 0·05 |
| Cell grey level | 131·27 ± 8·34 | 151·56 ± 12·78 | 158·10 ± 12·99 | 111·87 ± 9·73 |
| Nuclei surface area (μm2) | 50·43 ± 8·93 | 38·56 ± 8·36 | 38·09 ± 7·39 | 44·50 ± 9·17 |
| Nuclei circularity | 0·94 ± 0·01 | 0·94 ± 0·04 | 0·92 ± 0·02 | 0·91 ± 0·04 |
| Nuclei grey level | 85·11 ± 11·77 | 73·59 ± 13·00 | 90·13 ± 24·10 | 65·40 ± 11·77 |
| N/C ratio | 0·33 ± 0·08 | 0·41 ± 0·09 | 0·24 ± 0·07 | 0·41 ± 0·10 |
Circularity, surface areas and grey levels were calculated from the longitudinal cross-section of the shoot apex from a 10-year-old plant, using the ImageJ program in conjunction with the images in Fig. S1 (Supplementary Data, available online). Values are mean ± s.d. (n = 30 cells per zone). A circularity value of 1 corresponds to a perfect circle. As the value approaches 0, it indicates an increasingly elongated polygon. Grey levels correspond to means of grey levels in cell or nuclei (0, black; 255, white).
Abbreviations: CZ, central zone; PZ, peripheral zone; RZ, rib meristem-like zone; P1, emerging leaf primordium; N/C ratio, nucleo-cytoplasmic surface ratio.