Abstract
We report that, overexpression of OsNAC4, encoding plant specific transcription factor lead to HR cell death accompanied by the loss of plasma membrane integrity, nuclear DNA fragmentation and the typical morphological changes. In OsNAC4-knock down lines, HR cell death is markedly decreased in response to avirulent bacterial strains. The induced OsNAC4 by avirulent pathogen recognition signal is translocated into the nucleus in a phosphorylation-dependent manner. Microarray analysis demonstrated that expression of 139 genes including OsHSP90 and IREN, encoding Ca2+ dependent nuclease were different between the OsNAC4-knock down line and control line during the HR cell death. During the induction of HR cell death, OsHSP90 is involved in a loss of plasma membrane integrity, while IREN causes nuclear DNA fragmentation. Overall, our results indicate that two important events occurring during HR cell death are regulated by independent pathways.
