title: Molecular bases and evolutionary dynamics of self-incompatibility in the Pyrinae (Rosaceae).
abstract: The molecular bases of the gametophytic self-incompatibility (GSI) system of species of the subtribe Pyrinae (Rosaceae), such as apple and pear, have been widely studied in the last two decades. The characterization of S-locus genes and of the mechanisms underlying pollen acceptance or rejection have been topics of major interest. Besides the single pistil-side S determinant, the S-RNase, multiple related S-locus F-box genes seem to be involved in the determination of pollen S specificity. Here, we collect and review the state of the art of GSI in the Pyrinae. We emphasize recent genomic data that have contributed to unveiling the S-locus structure of the Pyrinae, and discuss their consistency with the models of self-recognition that have been proposed for Prunus and the Solanaceae. Experimental data suggest that the mechanism controlling pollen-pistil recognition specificity of the Pyrinae might fit well with the collaborative 'non-self' recognition system proposed for Petunia (Solanaceae), whereas it presents relevant differences with the mechanism exhibited by the species of the closely related genus Prunus, which uses a single evolutionarily divergent F-box gene as the pollen S determinant. The possible involvement of multiple pollen S genes in the GSI system of Pyrinae, still awaiting experimental confirmation, opens up new perspectives to our understanding of the evolution of S haplotypes, and of the evolution of S-RNase-based GSI within the Rosaceae family. Whereas S-locus genes encode the players determining self-recognition, pollen rejection in the Pyrinae seems to involve a complex cascade of downstream cellular events with significant similarities to programmed cell death.
authors.affiliation: Dipartimento di Colture Arboree (DCA), Università degli Studi di Bologna, Via Giuseppe Fanin 46, 40127 Bologna, Italy. pdefra@agrsci.unibo.it
authors.forename: Paolo
authors.initials: P
authors.lastname: De Franceschi
authors.forename: Luca
authors.initials: L
authors.lastname: Dondini
authors.forename: Javier
authors.initials: J
authors.lastname: Sanzol
mesh_terms: D005075:Biological Evolution; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011058:Pollen / Q000235:genetics* / Q000378:metabolism; D027824:Rosaceae / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins