Identification of differentially expressed proteins in response to Pb stress in Catharanthus roseus
Lead (Pb) is a widespread nonessential heavy metal in cells and causes molecular damage to plants through the formation of reactive oxygen species (ROS) which can be alleviated by enzymatic and nonenzymatic antioxidant machinery of the plant. In the present study, proteomic studies at 3, 6, 12 and 24 days demonstrated that the effect of 150 μM Pb on Catharanthus roseus. In response to Pb, a total of 76 proteins, out of the 95 differentially expressed proteins, were subjected to MALDI-TOF-MS Of these, 46 identities were identified by PMF and 19 identities were identified by microsequencing. Basic metabolisms such as photosynthesis, photorespiration and protein biosynthesis in C. roseus leaves were without exception strongly inhibited at the beginning of Pb treatment. On the other hand, tricarboxylic acid (TCA) cycle, glycolysis, shikimate pathway, phytochelatin synthesis, redox homeostasis and signaling proteins were induced during recovery period. Such defense systems play an important role in maintaining the survival and growth of C. roseus under strong and sustained oxidative stress.
Key words: Antioxidants, chlorophyll, MALDI-TOF-MS, oxidative stress, protein identification.