Chemical-induced apoptotic cell death in tomato cells: involvement of caspase-like proteases

A new system to study programmed cell death in plants is described. Tomato (Lycopersicon esculentum Mill.) suspension cells were induced to undergo pr ogrammed cell death by treatment with known inducers of apoptosis in mammal ian cells. This chemical-induced cell death was accompanied by the characte ristic features of apoptosis in animal cells, such as typical changes in nu clear morphology, the fragmentation of the nucleus and DNA fragmentation. I n search of processes involved in plant apoptotic cell death, specific enzy me inhibitors were tested for cell-death-inhibiting activity. Our results s howed that proteolysis plays a crucial role in apoptosis in plants. Further more, caspase-specific peptide inhibitors were found to be potent inhibitor s of the chemical-induced cell death in tomato cells, indicating that, as i n animal systems, caspase-like proteases are involved in the apoptotic cell death pathway in plants.