Table 1.
[2-14C]-Uracil (Ura) metabolism in rosette leaves of Arabidopsis seedlings grown for 6 wk in vermiculite and watered weekly with equal volumes of 1/2 × Murashige and Skoog (MS) medium containing 3 mm total nitrogen (1 mm KNO3 and 1 mm NH4NO3; 3 mm nitrogen), 0.4 mm total nitrogen (0.13 mm KNO3 and 0.13 mm NH4NO3), no nitrogen (− N) or 1 mm Ura as the sole nitrogen source
| Uracil metabolism (nmol g−1 FW) |
||||
|---|---|---|---|---|
| Sample | Soluble | Insoluble | Catabolic (14CO2) | Total incorporated |
| 3 mm N | 603 ± 57 (75) | 116 ± 9 (15) | 77 ± 8 (10) | 796.2 ± 73.5 |
| 0.4 mm N | 1058 ± 85* (76) | 207 ± 8*(15) | 130 ± 8* (9) | 1395 ± 100* |
| –N | 1168 ± 92* (82) | 145 ± 18 (10) | 121 ± 10* (8) | 1434 ± 119* |
| 1 mm Ura | 1180 ± 41* (60) | 466 ± 108* (24) | 325 ± 26* (16) | 1970 ± 173* |
Values are means ± standard error for four replicates. Values in parentheses indicate the percentage of total incorporated uracil. Soluble, perchloric acid-soluble fraction; Insoluble, perchloric acid-insoluble fraction.
*
Significant differences (P < 0.05) from 3 mm nitrogen metabolite profiles using unpaired two-tailed t-tests.