Introduction
Programmed cell death (PCD) plays an essential role in various plant developmental processes and is also a response to stress. The spectacular colours of leaves in autumn show an example of PCD. Plant defence systems often employ PCD to effectively block pathogen infection. These processes are being investigated by using Arabidopsis thaliana to study PCD in leaf senescence and both tomato and Arabidopsis thaliana to examine PCD in response to stress. The results could be applicable in plant biotechnology, such as stress tolerance and durable disease resistance, and be able to improve crop characteristics such as shelf life and productivity.