Table 1.
Leaf minor vein features and gas exchange for the Col-0 and low-vein-density Ei-5 accessions of Arabidopsis thaliana grown under a 9-h photoperiod of 100 μmol photons m-2 s-1 at a leaf temperature of 20°C.
| Low light |
|||
|---|---|---|---|
| Parameter | Col-0 | Ei-5 | P |
| Minor vein density (mm mm-2) | 2.12 @ 0.10 | 1.52 @ 0.12 | ∗∗∗ |
| Cells per minor vein | 39.4 @ 1.9 | 54.9 @ 1.4 | ∗∗∗ |
| Cells per minor vein × vein density | 83.8 @ 4.1 | 83.6 @ 2.1 | n.s. |
| Xylem cells per minor vein | 5.8 @ 0.6 | 10.7 @ 0.9 | ∗∗ |
| Phloem cells per minor vein | 30.6 @ 1.2 | 39.7 @ 1.7 | ∗∗ |
| Ratio of xylem to phloem cells | 0.187 @ 0.017 | 0.273 @ 0.034 | ∗ |
| Tracheary elements per minor vein | 3.46 @ 0.37 | 6.53 @ 0.47 | ∗∗ |
| Sieve elements per minor vein | 7.0 @ 0.4 | 10.2 @ 0.6 | ∗∗ |
| CCs + PCs per minor vein | 23.7 @ 0.8 | 29.5 @ 1.2 | ∗∗ |
| Ratio of tracheary to sieve elements | 0.509 @ 0.054 | 0.666 @ 0.069 | n.s. |
| Photosynthetic capacity (μmol O2 m-2 s-1) | 16.0 @ 3.3 | 16.0 @ 0.8 | n.s. |
| Phloem cells per minor vein × vein density | 65.1 @ 2.5 | 60.4 @ 2.6 | n.s. |
| Sieve elements per minor vein × vein density | 14.8 @ 0.9 | 15.5 @ 0.9 | n.s. |
| CCs + PCs per minor vein × vein density | 50.3 @ 1.8 | 44.9 @ 1.9 | ∗ |
| Transpiration ratio (mol H2O mol-1 CO2) | 321 @ 59 | 705 @ 206 | ∗∗ |
| Xylem cells per minor vein × vein density | 12.4 @ 1.4 | 16.3 @ 1.3 | ∗ |
| Tracheary elements per minor vein × vein density | 7.36 @ 0.79 | 9.95 @ 0.71 | ∗ |
Mean values ± standard deviation for vein density and gas exchange parameters and ± standard error for minor vein parameters; n = 3–4. The asterisks denote significant differences between the mean values; ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, and n.s., not significantly different. CC, companion cells; PC, phloem parenchyma cells.