Protein changes in response to pyrene stress in maize (Zea mays L.) leaves

Phytoremediation is a relatively new approach to remove polycyclic aromatic hydrocarbons (PAHs) from the environment. When plants are grown under pyrene treatment, they respond by synthesizing a set of protective proteins. To learn more about protein changes in response to pyrene treatment, we extracted total proteins from the leaves of maize (Zea mays L.) 1 week after pyrene treatment. The proteins extracted were separated with two-dimensional gel electrophoresis. In total, approximately 54 protein spots were found by comparing gels from treated and control groups. According to the isoelectric point, molecular weight, and abundance of these protein spots, 20 pyrene-induced proteins were found to have changed abundance. Of these, 15 protein spots were increased and five protein spots were newly appeared in pyrene-treated plant leaves. Six model upregulated protein spots of different molecular weights were excised from the gels and subjected to trypsin digestion followed by peptide separation using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Peptide masses were used to search the matrix-science database for protein identification. Two of the proteins were identified on the basis of the homology of their peptide profiles with existing protein sequences as pyruvate orthophosphate dikinase and the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit. These proteins are involved in the regulation of carbohydrate and energy metabolism. The present study gives new insights into the pyrene stress response in maize leaves and demonstrates the power of the proteomic approach in phytoremediation of PAHs.