Abstract
Rapid accumulation of reactive oxygen intermediates (e.g., H2O2) is a striking early event in the hypersensitive response including programmed cell death. Signaling pathways leading to these responses, however, remain to be dissolved. To elucidate the signaling pathways, eleven rice lesion mimic mutants spl (spl1-11) with spontaneous cell death on their leaves, were investigated using suspension-cultured cell system. Three of the mutants (spl2, spl7, spl11) were found to accumulate higher amount of H2O2 than the wild type, when treated with elicitor, indicating that these mutations are involved in accumulation of H2O2. Among three mutants, only spl7 mutant accumulated higher amounts of H2O2 than the wild type, when treated with calyculin A (CA), an inhibitor of protein phosphatase. Furthermore, spl2 mutant plant exhibited accelerated accumulation of H2O2 in response to wounding. We discuss the possible roles of these spl mutations in H2O2 generation.
