Abstract
Programmed cell death (PCD) plays a critical role during hypersensitive response (HR). One of components that trigger off PCD is H2O2, which may be generated through multiple pathways in planta. One example is proposed to be polyamine oxidation, but direct evidence for this has been limited. To investigate relationships among polyamines, H2O2 and PCD, we employed tobacco BY2 cells and cryptogein, an elicitor of HR. When BY2 cells were treated with cryptogein, PCD occurred. The level of H2O2 was simultaneously markedly increased, along with polyamine oxidase activity in apoplast. The same treatment in the presence of an inhibitor for polyamine biosynthesis, production of H2O2 was totally suppressed, and PCD did not occur. Suppression of polyamine oxidase activity with RNAi method led to the decreased level of PCD. These results suggest that polyamines are a direct source of H2O2 that is essential for induction of PCD involved in HR.
