Inferences on specificity recognition at the Malus×domestica gametophytic self-incompatibility system

Gametophytic Self-Incompatibility in Petunia

Gametophytic self-incompatibility (GSI), which prevents growth of a pollen tube through the style, provides a means of preventing self-pollination. Seen in most eudicot plant families, GSI in the genus Petunia was described by Darwin in the 19th century. By the time the first edition of this monograph was published in 1984, nearly a century later, most of the readily observable phenomena associ...

Convergent Evolution at the Gametophytic Self-Incompatibility System in Malus and Prunus

S-RNase-based gametophytic self-incompatibility (GSI) has evolved once before the split of the Asteridae and Rosidae. This conclusion is based on the phylogenetic history of the S-RNase that determines pistil specificity. In Rosaceae, molecular characterizations of Prunus species, and species from the tribe Pyreae (i.e., Malus, Pyrus, Sorbus) revealed different numbers of genes determining S-po...

Historical inferences from the self-incompatibility locus

Ancient polymorphism preserved at the self-incompatibility locus facilitates investigation of historical occurrences far older than extant species. We outline two ways in which studies of the S-locus can provide insights into patterns of speciation. First, we review evidence concerning the prevalence of founder events in speciation. A dramatic population size reduction is expected to reduce seq...

Protein Interactions in S-RNase-Based Gametophytic Self-Incompatibility

Loss of gametophytic self-incompatibility with evolution of inbreeding depression.

Gametophytic self-incompatibility (SI) in plants is a widespread mechanism preventing self-fertilization and the ensuing inbreeding depression, but it often evolves to self-compatibility. We analyze genetic mechanisms for the breakdown of gametophytic SI, incorporating a dynamic model for the evolution of inbreeding depression allowing for partial purging of nearly recessive lethal mutations by...