Separation of proteins from stressed rice (Oryza sativa L.) leaf tissues by two-dimensional polyacrylamide gel electrophoresis: induction of pathogenesis-related and cellular protectant proteins by jasmonic acid, UV irradiation and copper chloride.

We have used three kinds of stresses, including the signaling compound jasmonic acid, an environmental stressor, UV irradiation, and a heavy metal salt copper chloride, to study changes in the protein patterns in rice (Oryza sativa L.) leaf tissues using two-dimensional polyacrylamide gel electrophoresis. However, instead of using lysis buffer containing urea (O'Farrell, J. Biol. Chem. 1975, 250, 4007-4021) for extraction of proteins from rice seedling tissues, we used Tris-HCl buffer (commonly used for extraction of proteins for separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) for extraction of proteins and resolved these extracted proteins by the usual method of O'Farrell. Furthermore, the induction of a large number of proteins was clearly observed over controls. No spots corresponding to these induced proteins were found in the control experiment, indicating qualitative changes in protein patterns after various stress treatments. A total of 12 out of 13 proteins could be N-terminally sequenced from jasmonic acid-treated rice leaf tissues, and one protein was sequenced from UV-irradiated leaf tissues. These proteins showed high homology to pathogenesis-related (thaumatin-like protein, a PR5 class protein; a beta-1,3-glucanase precursor; an intracellular PR protein encoded by PBZ1 gene, and an antifungal protein) and cellular protectant (glutathione transferase, EC 2.5.1.18; and ascorbate peroxidase) proteins, from plants, including rice. Results presented here suggest a role for jasmonic acid in the self-defense mechanisms of rice plants.