Table 3.
14CO2 partitioningDetached, fully expanded leaves from 7-week-old dark-adapted Arabidopsis plants were enclosed in an incubation chamber under saturated 14CO2 and light for 40min. Three leaves per genotype harvested from independent plants were used and randomly distributed within the chamber to compensate for possible CO2 concentration gradients. The incorporation of 14C into soluble and insoluble fractions was determined after hot ethanol extraction. The soluble extract was further fractionated using ion exchange chromatography into neutral (predominantly free sugars), anionic (phosphorylated intermediates in fraction anionic I and carboxylic acids in fraction anionic II), and cationic (free amino acids) fractions. The values are given as a percentage of total 14C incorporation. The experiment was repeated twice with similar results.
| Col-0 | spsa1 | spsc | spsa1/spsc | |
|---|---|---|---|---|
| Total incorporation (μmol 14 C g FW–1) | 365±114 | 305±81 | 349±43 | 323±89 |
| Soluble | 46.5±2.5 | 46.1±3.4 | 49.7±1.8 | 41.7±4.3 |
| Insoluble | 53.5±2.5 | 53.9±3.4 | 50.3±1.8 | 58.3±4.3 |
| Neutral | 13.0±1.2 | 11.8±1.5 | 14.6±1.3 | 10.0±1.6 |
| Anionic I | 1.13±0.11 | 0.99±0.16 | 1.08±0.09 | 0.62±0.08* |
| Anionic II | 0.80±0.10 | 0.89±0.08 | 0.65±0.08 | 0.72±0.05 |
| Cationic | 0.15±0.01 | 0.20±0.02 | 0.14±0.03 | 0.19±0.03 |
Values represent the mean (± SE) from five different plants.
An asterisk indicate a significant difference at P<0.05 from the wild type according to t-test.