Jasmonic acid-induced necrosis and drastic decreases in ribulose-1,5-bisphosphate carboxylase/oxygenase in rice seedlings under light involves reactive oxygen species

Leaves and leaf sheaths of rice (Oryza sativa L.) seedlings responded to 100 μmol/L jasmonic acid with necrotic lesions and browning, respectively. By SDS-PAGE and immunoblot analysis, light-, dose- and time-dependent drastic reductions in ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) were found in jasmonate-treated leaves and leaf sheaths. Cycloheximide, free radical scavengers, a metal chelator, and protease and photosystem II inhibitors significantly reversed decrease in RuBisCO protein. Polypeptides were induced in light-incubated jasmonate-treated leaf sheaths. Surprisingly in dark incubated leaves only, induction was blocked by cycloheximide, indicatingde novo synthesis. Photosystem II inhibitors, the metal chelators 1,10-phenanthroline and EDTA, and a protease inhibitor, tosyl-lysine chloromethyl ketone, also blocked polypaptide induction, whereas free radical scavengers were only partially effective. Results indicate that jasmonate action in rice may be mediated through inhibition or damage of photosynthesis via production of reactive oxygen species and leading to necrotic lesion formation.