Review Plant programmed cell death: A common way to die Antoine Danon, Valérie Delorme, Nathalie Mailhac, Patrick Gallois * Laboratoire génome et développement des plantes, université de Perpignan (CNRS, UMR 5096), 52, avenue de Villeneuve, 66860 Perpignan cedex, France Received 2 February 2000; accepted 7 June 2000 Abstract – In the last few years programmed cell death in plants inspired many studies in development and environmental stresses. Some of these studies showed that hallmarks of animal programmed cell death were found at cellular or molecular level in plant cells in different experimental systems. Additionally the effect of over-expression in plants of animal genes implicated in programmed cell death has been tested, and some plant homologues of these genes have been found. This suggests that, despite some differences, plants and animals could share at least some common components of a core mechanism used to carry out programmed cell death in eukaryotes. In this review, we will concentrate on the last findings that suggest similarity between plant programmed cell death and its better known counterpart in animals. © 2000 Éditions scientifiques et médicales Elsevier SAS apoptosis / caspases / DNA ladder / necrosis / plants / programmed cell death / TUNEL bp, base pair / HR, hypersensitive reaction / PCD, programmed cell death / PARP, poly (ADP-ribose) polymerase / TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling 1. INTRODUCTION In animal development, a genetically controlled cell death, termed programmed cell death (PCD), occurs at different stages of growth, for example to eliminate cells between developing digits or degeneration of neurones that fail to form proper cellular connections. Some cells also die during the organism’s life cycle to regulate the size of distinct cell population in tissues. Additionally when cells are confronted with environ- mental stresses, they can either be destroyed acciden- tally (murder), or can self-destruct using an active mechanism (suicide). This depends on the stress type or intensity. Inappropriate programmed cell death is implicated in several human diseases such as Alzhe- imer’s, Parkinson’s, AIDS or cancers (reviewed in [49]). In plants, it has been known for some time that a genetically controlled cell death plays a role in some of the processes of development and defence mecha- nisms. For example lesion-mimic mutants, where a localised cell death is triggered due to a genetic defect, are a good illustration of the concept. Several studies of plant cell death have been carried out to elucidate the underlying molecular mechanism. Either of two strategies has been used. First, molecular data can be obtained using mutant studies or classical screening approaches. Second, it is tempting to draw a parallel between plant and animal cell death, so researchers looked for the hallmarks currently used in animal studies to discriminate between programmed and acci- dental cell death, and for plant homologues of animal genes implicated in programmed cell death. The involvement of cell death in different aspects of the plant life cycle has already been reviewed [38], including the death response to plant pathogen attack and its specific signalling (e.g. salicylic acid, reactive oxygen species, etc.) [30, 39]. Identifying ancestral components in plant PCD is crucial to fully understand this process. Therefore in this paper, we will concen- trate on reporting the latest findings concerning the similarities between plant cell death and animal PCD. This will show that in plants the research in the field of PCD is at a turning point. * Correspondence and reprints: fax +33 4 6866 8499; e-mail gallois@univ-perp.fr Plant Physiol. Biochem. 38 (2000) 647-655 © 2000 Éditions scientifiques et médicales Elsevier SAS. All rights reserved S0981942800011785/REV