Table 2.
Effects of different stress factors and signal compounds on the protein level of all four pmPOX from maize seedlings
| Treatment | Treatment times (h) | Relative protein spot intensity (%) |
|||
| pmPOX1 | pmPOX2a | pmPOX2b | pmPOX3 | ||
| Control | 100.0±17.1 (21/63) | 100.0±15.7 (24/72) | 100.0±18.0 (21/63) | 100.0±15.3 (24/72) | |
| H2O2 | 1 | 111.0±44.9 (5/15) | 158.9±24.4 (6/18)** | 244.8±60.8 (4/12)** | 47.7±4.3 (6/18)* |
| Wounding | 1 | 100.3±5.1 (6/18) | 87.4±11.2 (8/24) | 52.7±4.1 (6/18)* | 79.5±9.3 (8/24) |
| Methyl jasmonate | 1 | 147.9±14.6 (6/18)** | 251.8±25.3 (6/18)* | 267.3±21.2 (4/12)* | 628.0±166.2 (6/18)* |
| Salicylic acid | 1 | 347.0±81.1 (4/12)* | 188.8±39.7 (6/18)** | 877.4±306.5 (4/12)** | 422.3±87.4 (6/18)* |
| F. graminearum extract | 4 | 113.5±18.2 (4/12) | 65.3±6.9(6/18)* | 233.0±42.5 (4/12)** | 113.8±23.0 (6/18) |
| F. culmorum extract | 4 | 183.0±40.9 (4/12)** | 182.9±23.1 (6/18)* | 165.3±23.8 (4/12)* | 241.0±14.9 (6/18)* |
| Chitosan | 4 | 136.7±23.2 (4/12)** | 169.7±20.0 (6/18)* | 256.7±71.5 (4/12)** | 981.7±99.0 (6/18)* |
| Cantharidin | 1 | 72.3±12.3 (4/12)** | 59.4±5.9 (6/18)* | 192.4±25.1 (4/12)** | 98.6±15.3 (6/18) |
5-d-old maize seedlings were exposed to different stressors as indicated. Each treatment was analysed using 2–3 independent experiments, i.e. each experiment with approximately 900 plant seedlings. Treated and control plants and samples were handled in parallel throughout all subsequent steps. For each experiment solubilizates from isolated wPM were repeatedly separated by 2D PAGE analysis (isoelectric focusing and non-reducing modified gradient SDS-PAGE, Fig. 4). As described earlier, thus, oligomers and haem proteins remain intact (Mika and Lüthe, 2003). PM-bound peroxidases were identified by staining with guaiacol and H2O2. Relative spot intensities representing protein abundance were analysed and calculated in comparison with direct controls. Isoelectric focusing was performed in two different overlapping ampholyte gradients to provide optimal separation of the pmPOX. Shown are means ±SE (n=analysed 2D gels/gel pictures). SE of controls for single independent treatments were ≤4%. Values that were significantly different from controls in t test analysis were marked at P < 0.001 (*) and P < 0.05 (**). The proteomic analysis revealed strong changes in protein biosynthesis of all four pmPOX proteins after different treatments.