Table 1.
Subcellular distribution of metabolite levels in developing barley endosperm tissue at 14 DAF
| Metabolite | Tissue content (nmol g FW−1) | Subcellular distribution (%) |
Subcellular levels (nmol g FW−1) |
Subcellular concentrations (mM) |
||||
| Cytosol | Plastid | Cytosol | Plastid | Cytosol | Plastid | |||
| Sucrose | 75 000.0 | 91.2±2.9 | 8.8±2.9 | 68 432.9±2209.4 | 6603.2±2209.4 | 138.248±5.860 | 13.076±4.505 | |
| Fructose | 2500.0 | 82.2±2.7 | 17.8±2.7 | 2024.5±65.4 | 438.4±65.4 | 4.090±0.173 | 0.868±0.138 | |
| Gluc-1-P | 42.2 | 85.2±5.4 | 14.8±5.4 | 36.0±2.3 | 6.3±2.3 | 0.073±0.005 | 0.012±0.005 | |
| Gluc-6-P | 686.6 | 87.5±4.2 | 12.5±4.2 | 600.7±28.5 | 85.8±28.5 | 1.214±0.070 | 0.170±0.058 | |
| Fruc-6-P | 152.1 | 75.5±5.0 | 24.5±5.0 | 114.8±7.6 | 37.3±7.6 | 0.232±0.018 | 0.074±0.016 | |
| Fruc-1,6-bisP | 23.5 | 91.5±2.3 | 8.5±2.3 | 21.5±0.5 | 2.0±0.5 | 0.044±0.002 | 0.004±0.001 | |
| DHAP | 31.7 | 95.5±0.0 | 4.5±0.0 | 30.3±0.0 | 1.4±0.0 | 0.061±0.001 | 0.003±0.000 | |
| GAP | 12.8 | 98.0±0.0 | 2.0±0.0 | 12.5±0.0 | 0.3±0.0 | 0.025±0.000 | 0.001±0.000 | |
| 3-PGA | 277.5 | 85.8±5.3 | 14.2±5.3 | 238.1±14.6 | 39.4±14.6 | 0.481±0.034 | 0.078±0.030 | |
| PEP | 43.7 | 87.8±0.9 | 12.2±0.9 | 38.4±0.4 | 5.3±0.4 | 0.078±0.002 | 0.011±0.001 | |
| Pyruvate | 61.9 | 78.8±5.2 | 21.2±5.2 | 48.8±3.2 | 13.1±3.2 | 0.099±0.007 | 0.026±0.007 | |
| Citrate | 1805.2 | 91.2±4.3 | 8.8±4.3 | 1646.3±78.2 | 158.9±78.2 | 3.326±0.192 | 0.315±0.158 | |
| Isocitrate | 260.0 | 91.8±3.7 | 8.2±3.7 | 238.7±9.6 | 21.3±9.6 | 0.482±0.024 | 0.042±0.019 | |
| Oxoglutarate | 148.0 | 93.8±1.7 | 6.2±1.7 | 138.8±2.5 | 9.2±2.5 | 0.280±0.008 | 0.018±0.005 | |
| Malate | 406.3 | 91.2±2.6 | 8.8±2.6 | 370.5±10.6 | 35.8±10.6 | 0.749±0.029 | 0.071±0.022 | |
| ADPG | 146.0 | 91.0±2.7 | 9.0±2.7 | 132.9±3.9 | 13.1±3.9 | 0.268±0.011 | 0.026±0.008 | |
| ATP | 258.9 | 87.2±3.5 | 12.8±3.5 | 225.8±9.1 | 33.1±9.1 | 0.456±0.023 | 0.066±0.019 | |
| ADP | 139.2 | 33.0±2.9 | 67.0±2.9 | 45.9±4.0 | 93.3±4.0 | 0.093±0.009 | 0.185±0.010 | |
| AMP | 103.4 | 46.7±5.0 | 53.3±5.0 | 48.3±5.1 | 55.1±5.1 | 0.098±0.011 | 0.109±0.011 | |
| UDPG | 190.9 | 86.5±2.7 | 13.5±2.7 | 165.1±5.1 | 25.8±5.1 | 0.334±0.014 | 0.051±0.011 | |
| UTP | 120.3 | 94.2±1.3 | 5.8±1.3 | 113.3±1.6 | 7.0±1.6 | 0.229±0.006 | 0.014±0.003 | |
| UDP | 52.8 | 83.3±2.7 | 16.7±2.7 | 44.0±1.4 | 8.8±1.4 | 0.089±0.004 | 0.017±0.003 | |
| UMP | 59.6 | 85.2±2.3 | 14.8±2.3 | 50.8±1.4 | 8.8±1.4 | 0.103±0.004 | 0.017±0.003 | |
| GTP | 91.3 | 92.8±2.7 | 7.2±2.7 | 84.8±2.4 | 6.6±2.4 | 0.171±0.007 | 0.013±0.005 | |
| GDP | 42.8 | 93.2±2.3 | 6.8±2.3 | 39.9±1.0 | 2.9±1.0 | 0.081±0.003 | 0.006±0.002 | |
| GMP | 27.9 | 70.2±4.9 | 29.8±4.9 | 19.6±1.4 | 8.3±1.4 | 0.040±0.003 | 0.016±0.003 | |
| PPi | 70.7 | 86.8±4.7 | 13.2±4.7 | 61.4±3.3 | 9.3±3.3 | 0.124±0.008 | 0.018±0.007 | |
| Pi | 16 600.0 | 80.2±4.4 | 19.8±4.4 | 13 337.1±729.7 | 3292.7±729.7 | 26.944±1.746 | 6.520±1.509 | |
For three separate gradients deriving from the same pool of tissue, the percentage subcellular distribution of the respective metabolite was calculated. The data shown are the mean ±SE (n=3 different gradients). The levels of the respective metabolite (nmol g FW−1) in cytosol and plastid were calculated by multiplying the tissue content by the percentage subcellular distribution of the respective metabolite for each gradient separately. The obtained values for cytosolic and plastidial metabolite levels from the different gradients were then used to calculate the mean ±SE (n=3 different gradients).
To calculate the subcellular concentration (in μM), the mean subcellular metabolite level was divided by the mean value of the percentage distribution of the respective subcellular volume (see Fig. 2). In this case, both the relative error of the respective metabolite level and that of the subcellular volume distribution were added to show the limits of variation. Cytosol also includes minor contributions of mitochondria and vacuoles that could not be further separated. Data are the mean ±SE (n=3 different experiments).