title: Self-incompatibility in Papaver: advances in integrating the signalling network.
abstract: Self-fertilization, which results in reduced fitness of offspring, is a common problem in hermaphrodite angiosperms. To prevent this, many plants utilize SI (self-incompatibility), which is determined by the multi-allelic S-locus, that allows discrimination between self (incompatible) and non-self (compatible) pollen by the pistil. In poppy (Papaver rhoeas), the pistil S-determinant (PrsS) is a small secreted protein which interacts with the pollen S-determinant PrpS, a ~20 kDa novel transmembrane protein. Interaction of matching pollen and pistil S-determinants results in self-recognition, initiating a Ca²⁺-dependent signalling network in incompatible pollen. This triggers several downstream events, including alterations to the cytoskeleton, phosphorylation of sPPases (soluble inorganic pyrophosphatases) and an MAPK (mitogen-activated protein kinase), increases in ROS (reactive oxygen species) and nitric oxide (NO), and activation of several caspase-like activities. This results in the inhibition of pollen tube growth, prevention of self-fertilization and ultimately PCD (programmed cell death) in incompatible pollen. The present review focuses on our current understanding of the integration of these signals with their targets in the SI/PCD network. We also discuss our recent functional expression of PrpS in Arabidopsis thaliana pollen.
authors.affiliation: *School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Eaves
authors.affiliation: *School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Carlos
authors.initials: C
authors.lastname: Flores-Ortiz
authors.affiliation: *School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Tamanna
authors.initials: T
authors.lastname: Haque
authors.affiliation: *School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Zongcheng
authors.initials: Z
authors.lastname: Lin
authors.affiliation: *School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Nianjun
authors.initials: N
authors.lastname: Teng
authors.affiliation: *School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, U.K.
authors.forename: Vernonica E
authors.initials: VE
authors.lastname: Franklin-Tong
mesh_terms: D003599:Cytoskeleton / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010207:Papaver / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D054817:Pollination / Q000235:genetics / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D017382:Reactive Oxygen Species; D009569:Nitric Oxide