title: Initiation of programmed cell death in self-incompatibility: role for cytoskeleton modifications and several caspase-like activities.
abstract: Programmed cell death (PCD) is an important and universal process regulating precise death of unwanted cells in eukaryotes. In plants, the existence of PCD has been firmly established for about a decade, and many components shown to be involved in apoptosis/PCD in mammalian systems are found in plant cells undergoing PCD. Here, we review work from our lab demonstrating the involvement of PCD in the self-incompatibility response in Papaver rhoeas pollen. This utilization of PCD as a consequence of a specific pollen-pistil interaction provides a very neat way to destroy unwanted 'self', but not 'non-self' pollen. We discuss recent data providing evidence for SI-induced activation of several caspase-like activities and suggest that an acidification of the cytosol may be a key turning point in the activation of caspase-like proteases executing PCD. We also review data showing the involvement of the actin and microtubule cytoskeletons as well as that of a MAPK in signalling to caspase-mediated PCD. Potential links between these various components in signalling to PCD are discussed. Together, this begins to build a picture of PCD in a single cell system, triggered by a receptor-ligand interaction.
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham. B15 2TT, UK.
authors.forename: Maurice
authors.initials: M
authors.lastname: Bosch
authors.forename: Natalie S
authors.initials: NS
authors.lastname: Poulter
authors.forename: Sabina
authors.initials: S
authors.lastname: Vatovec
authors.forename: Vernonica E
authors.initials: VE
authors.lastname: Franklin-Tong
mesh_terms: D000199:Actins / Q000378:metabolism; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism*; D003599:Cytoskeleton / Q000201:enzymology*; D053205:Pollen Tube / Q000201:enzymology; D054817:Pollination / Q000502:physiology*
chemical_list: D000199:Actins; D020169:Caspases