Interspecific hybridization and polyploidy are key processes in plant evolution and are responsible for ongoing genetic diversification in the genus Sorbus (Rosaceae). Ludwig et al. study mating systems of diploid, triploid and tetraploid taxa in a diversity ‘hotspot’ for Sorbus in south-west England and find mating inter-relationships to be complex, and to provide the driving force [...]

Birds can be alternative pollinators for winter-flowering plants outside the tropics where low temperatures limit insect activity. Feng et al. observe pollinator visitation to loquat (Eriobotrya japonica, Rosaceae) and exclude birds and other animals from the flowers. They determine that in late winter two passerine birds (Pycnonotus sinensis and Zosterops japonicus) are effective pollinators, and that [...]

In grasses, self-incompatibilty (SI) is based on two loci, S and Z, but the mechanisms are much less well understood relative to other gametophytic SI systems. Klass et al. review recent progress towards elucidating grass SI, and by identifying Ca binding and kinase domains from subtracted Lolium stigma cDNA libraries they strengthen the case for involvement [...]

S-RNase-based self-incompatibility (SI) occurs in the Solanaceae, Rosaceae and Plantaginaceae, with S-RNases determining the specificity of pollen rejection in the pistil and S-locus F-box proteins fulfilling this function in pollen. McClure et al. introduce the genetics of SI and briefly describe the characteristics of S-RNases and pollen F-box proteins. Two alternative mechanisms have been proposed whereby [...]

Pollen–pistil interactions are an essential prelude to fertilization in angiosperms, and self-incompatibility (SI) is the best understood of these at a molecular level. Allen et al. review studies in the Asteraceae, and consider that recent cellular and molecular work in Senecio squalidus (Oxford ragwort) have challenged the belief that sporophytic SI and pollen–pistil interactions in [...]

Self-incompatibility (SI) is generally controlled by the S-locus, and comprises allelic pollen and pistil S-determinants. Poulter et al. review and discuss our current understanding of the cytoskeletal alterations induced in incompatible pollen during SI and their relationship with programmed cell death in Papaver rhoeas, focussing on data relating to the formation of F-actin punctate foci. Analysis [...]

S-RNase-based self-incompatibility in Petunia In Solanaceae-type self-incompatibility, the specificity of self/non-self interactions between pollen and pistil is controlled by two polymorphic genes at the S-locus, with S-locus F-box gene (SLF or SFB) controlling pollen specificity and S-RNase gene controlling pistil specificity. Meng et al.  summarize their recent results on the identification and functional studies of [...]