Abstract
Plant hypersensitive cell death (HR cell death) is a form of plant programmed cell death and plays a major role in plant immunity. We previously demonstrated that HR cell death is initiated by a plant specific transcription factor, OsNAC4. To clarify mechanism of HR cell death induction by OsNAC4, we compared global gene expressions in OsNAC4 RNAi line and in a control line using a 22,000 elements oligonucleotide microarray. Variations of 143 genes were abolished in the RNAi line during the incompatible interaction. All genes were upregulated in control line by inoculation of the incompatible N1141 strain, indicating that OsNAC4 positively regulated expression of these genes. We analyzed in depth the sequence motif of all 143 genes and only one cDNA encoding putative endonuclease (OsHEN1) was found. When OsHEN1 was expressed in rice cells, clear nuclear DNA cleavage was observed. These data indicate that OsNAC4 induced DNA degradation through OsHEN1.
