Table IV.

14CO2 partitioning

Leaf discs from dark-treated tobacco plants were enclosed in oxygen electrodes under saturated 14CO2 and light for 20 min. The incorporation of 14C into soluble and insoluble fractions was determined after hot ethanol extraction. The soluble extract is further fractionated using ion-exchange chromatography into neutral, anionic, and cationic fractions. The total incorporation is given in disintegrations per min and the other values are given in percentage of total incorporation. Values represent the mean (±sd) from five different plants.

FractionControlNtSPSAi41NtSPSAi62NtSPSCi20NtSPSCi35
Total (dpm)6,518 ± 1,8555,339 ± 1,4455,181 ± 1,5738,374 ± 2,0878,913 ± 3,079
Insoluble39.2 ± 3.542.1 ± 4.142.7 ± 3.841.3 ± 3.542.5 ± 5.2
Soluble60.8 ± 3.557.9 ± 4.157.3 ± 3.858.7 ± 3.557.5 ± 5.2
Neutral46.7 ± 4.648.7 ± 9.541.6 ± 8.041.9 ± 4.340.6 ± 14.4
Anionic8.7 ± 3.88.2 ± 2.09.9 ± 3.87.4 ± 0.57.8 ± 2.9
Cationic6.9 ± 0.78.8 ± 1.49.1 ± 0.68.1 ± 0.87.9 ± 0.7