Construction of a cell-free system using extracts from apoptotic plant cells

To study the mechanism of plant apoptosis, a cell-free system has been developed using the extracts prepared from tobacco cells that become committed to apoptosis induced by heat shock treatment. Tobacco nuclei have displayed such characteristics of apoptosis as nucleus condensation and formation of apoptotic bodies during incubation in this system. Besides, these morphological changes are accompanied by DNA fragmentation, which is detected by DNA laddering and comet assay. Furthermore, both morphological changes and DNA cleavage are not affected by pepstatin A, leupeptin or EDTA, but are partly inhibited by iodoacetamide. This profile is consistent with Caspases, which are vital to animal apoptosis, suggesting that cysteine-protease like Caspases may be involved in apoptosis in plants.