Programmed cell death (PCD) is a fundamental process that is recognized to occur in eukaryotes and prokaryotes. During development of a multicellular organism, certain cells are destined to turnover in relatively predictable times and places. In addition, environmental and hormonal signals can also activate a cellular suicide program.
Although PCD has been intensely studied in the past decade, particularly in mammalian cells and C. elegans, the actual mechanism through which eukaryotic cells commit suicide remains enigmatic. The current working hypothesis in this field is that the cellular machinery for PCD is present all the time in eukaryotic cells and is actively suppressed by certain proteins. This exciting finding suggests that the underlying mechanism for PCD may be conserved across plant and animal kingdoms.
A tobacco leaf inoculated with Pseudomonas syringae bacteria exhibits the hypersensitive response (zones 1 and 2), a type of programmed cell death induced by pathogens.
Comparison of PCD in plants and animals. (a) Hypersensitive response in plant cells. (b) Development of tracheary elements in plants. (c) Apoptosis in animal cells. Click to enlarge.
PCD in Plants
Our aim is to further the understanding of the regulation of PCD in plants at the molecular and biochemical levels. To this end, we have been studying to ascertain functional roles of evolutionary conserved proteins, metacaspases (MCPs) and Bax inhibitor-1 (BI-1), in the regulation of plant PCD and its related stress signaling/response. For such research, we use the model organisms, such as Arabidopsis thaliana and tobacco (Nicotiana tabacum), and a combined technique of molecular genetics, biochemistry, cell biology and post-genomic tools.