Table 1.
The total number of phloem cells, the total number of xylem cells, and the ratio of phloem cell number to xylem cell number per minor loading (third- and fourth-order) vein in leaves of the Italian, Col-0, and Swedish ecotypes of A. thaliana grown under four different temperature and PFD regimes.
| Ecotype | Vascular metric | Leaf temperature and PFD in μmol photons m−2 s−1 during growth | |||
|---|---|---|---|---|---|
| 25°C, 400 | 25°C, 1000 | 14°C, 400 | 14°C, 1000 | ||
| Italian | No. of phloem cells | 34 ± 1b | 36 ± 2a, b | 36 ± 1a, b | 40 ± 2a |
| No. of xylem cells | 13 ± 1 n.s. | 12 ± 1 | 12 ± 1 | 12 ± 1 | |
| phloem/xylem | 2.6 | 3 | 3 | 3.3 | |
| Col-0 | No. of phloem cells | 32 ± 1b | 33 ± 1b | 38 ± 3b | 49 ± 2a |
| No. of xylem cells | 13 ± 1 n.s. | 10 ± 1 | 10 ± 1 | 13 ± 1 | |
| phloem/xylem | 2.5 | 3.3 | 3.8 | 3.8 | |
| Swedish | No. of phloem cells | 35 ± 1b | 36 ± 1b | 47 ± 1a | 53 ± 2a |
| No. of xylem cells | 13 ± 1 n.s. | 15 ± 1 | 13 ± 1 | 15 ± 1 | |
| phloem/xylem | 2.7 | 2.4 | 3.6 | 3.5 | |
Means ± standard error of the mean (n = 4) and statistically significant differences indicated with lower case letters, i.e., means sharing a common letter are not statistically different from one another, P < 0.05, n.s., not significantly different. Statistics conducted independently for number of phloem and xylem cells per vein within each ecotype, i.e., comparisons conducted horizontally in the table.