1. Identification of the pollen self-incompatibility determinant in Papaver rhoeas
- Author
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Wheeler, Michael J., de Graaf, Barend H. J., Hadjiosif, Natalie, Perry, Ruth M., Poulter, Natalie S., Osman, Kim, and Vatovec, Sabina
- Subjects
Plants -- Self-incompatibility ,Corn poppy -- Physiological aspects -- Genetic aspects -- Analysis ,Pollen -- Identification and classification -- Physiological aspects -- Genetic aspects -- Analysis ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Poppies' self awareness Self-incompatibility is an important mechanism in many plant species, used to prevent inbreeding by ensuring rejection of 'self' pollen. It is controlled by a multi-allelic S locus, comprising pollen (male) and pistil (female) S determinants. Wheeler et al. have cloned three alleles of a highly polymorphic pollen-expressed gene, PrpS, from the common poppy Papaver rhoeas, which has no homologues in existing databases. PrpS is a transmembrane protein that appears to function as the pollen S-locus determinant. This adds to our knowledge of the evolution of cell-cell recognition systems. Self-incompatibility is an important mechanism used in many species to prevent inbreeding by ensuring rejection of 'self' pollen. The cloning of three alleles of a highly polymorphic pollen-expressed gene, PrpS (Papaver rhoeas pollen S), now provides evidence that it encodes the pollen S locus determinant and adds to our knowledge of the evolution of cell-cell recognition systems. Higher plants produce seed through pollination, using specific interactions between pollen and pistil. Self-incompatibility is an important mechanism used in many species to prevent inbreeding; it is controlled by a multi-allelic S locus.sup.1,2. 'Self' (incompatible) pollen is discriminated from 'non-self' (compatible) pollen by interaction of pollen and pistil S locus components, and is subsequently inhibited. In Papaver rhoeas, the pistil S locus product is a small protein that interacts with incompatible pollen, triggering a Ca.sup.2+-dependent signalling network, resulting in pollen inhibition and programmed cell death.sup.3,4,5,6,7. Here we have cloned three alleles of a highly polymorphic pollen-expressed gene, PrpS (Papaver rhoeas pollen S), from Papaver and provide evidence that this encodes the pollen S locus determinant. PrpS is a single-copy gene linked to the pistil S gene (currently called S, but referred to hereafter as PrsS for Papaver rhoeas stigma S determinant). Sequence analysis indicates that PrsS and PrpS are equally ancient and probably co-evolved. PrpS encodes a novel ~20-kDa protein. Consistent with predictions that it is a transmembrane protein, PrpS is associated with the plasma membrane. We show that a predicted extracellular loop segment of PrpS interacts with PrsS and, using PrpS antisense oligonucleotides, we demonstrate that PrpS is involved in S-specific inhibition of incompatible pollen. Identification of PrpS represents a major advance in our understanding of the Papaver self-incompatibility system. As a novel cell-cell recognition determinant it contributes to the available information concerning the origins and evolution of cell-cell recognition systems involved in discrimination between self and non-self, which also include histocompatibility systems in primitive chordates and vertebrates., Author(s): Michael J. Wheeler [sup.1] [sup.3] , Barend H. J. de Graaf [sup.1] [sup.3] , Natalie Hadjiosif [sup.1] , Ruth M. Perry [sup.1] , Natalie S. Poulter [sup.1] , Kim [...]
- Published
- 2009
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