Abstract
The hypersensitive response (HR), a form of programmed cell death that occurs during immune responses in plants, is characterized by a distinct cellular morphology, including plasma membrane shrinkage, nuclear condensation, and DNA fragmentation. Initiation of HR cell death requires de novo protein synthesis, suggesting that the induction of HR cell death involves a transcriptional network regulated by a key factor. PCR-subtraction and cDNA microarray analyses revealed that plant specific transcription factor OsNAC4 is specifically induced during HR cell death. Overexpression of OsNAC4 caused HR-cell death accompanied with DNA fragmentation. In cell lines in which OsNAC4 levels have been suppressed by RNAi, HR cell death was markedly decreased in response to incompatible bacterial strains. In addition, recognition of plant immune initiation signal causes accumulation of OsNAC4 in the cytosol and its translocation from the cytosol to the nucleus. These data indicate that OsNAC4 is a positive regulator of HR cell death.
