Abstract: 【Objective】Using a tobacco (Nicotiana tobacum) cell culture and parasiticein, the protein from oomycete pathogen Phytophthora parasitica, we observed serial reactions of the dead cells.【Method】Tobacco suspension cultures were subjected to 100nmol/L parasiticein and used to observe morphological aspects of dead cell by phase contrast microscopy.【Results】In the early phase, dead cells showed that the cell membrane retracts and moves away from the cell wall leaving a visible gap. In the later phase the cytoplasm shrinkaged. The same aspects can be obtained after stained with trypan blue. Using fluorescence microscopy, chromatin morphology was observed by DAPI staining. Chromatin had a granular appearance with lobated nuclei in some cells treated with parasiticein. DNA laddering was found in dead cells after separated on a 2.0% (w/v) agarose gel. Also we found that the death of the cell induced by parasiticein was partially inhibited by K252-a, an inhibitor of protein kinase.【Conclusion】Those data suggest that parasiticein-induced cell death shows many morphological and biochemical properties of PCD.

Key words: Parasiticein, Programmed cell death, cytoplasm shrinkage, chromatin condensation, DNA laddering