title: Convergent evolution at the gametophytic self-incompatibility system in Malus and Prunus.
abstract: 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-pollen specificity. In Prunus only one pistil and pollen gene determine GSI, while in Pyreae there is one pistil but multiple pollen genes, implying different specificity recognition mechanisms. It is thus conceivable that within Rosaceae the genes involved in GSI in the two lineages are not orthologous but possibly paralogous. To address this hypothesis we characterised the S-RNase lineage and S-pollen lineage genes present in the genomes of five Rosaceae species from three genera: M. × domestica (apple, self-incompatible (SI); tribe Pyreae), P. persica (peach, self-compatible (SC); Amygdaleae), P. mume (mei, SI; Amygdaleae), Fragaria vesca (strawberry, SC; Potentilleae), and F. nipponica (mori-ichigo, SI; Potentilleae). Phylogenetic analyses revealed that the Malus and Prunus S-RNase and S-pollen genes belong to distinct gene lineages, and that only Prunus S-RNase and SFB-lineage genes are present in Fragaria. Thus, S-RNase based GSI system of Malus evolved independently from the ancestral system of Rosaceae. Using expression patterns based on RNA-seq data, the ancestral S-RNase lineage gene is inferred to be expressed in pistils only, while the ancestral S-pollen lineage gene is inferred to be expressed in tissues other than pollen.
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Bruno
authors.initials: B
authors.lastname: Aguiar
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Jorge
authors.initials: J
authors.lastname: Vieira
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Ana E
authors.initials: AE
authors.lastname: Cunha
authors.affiliation: CRACS-INESC Porto, Rua do Campo Alegre 1021/1055, 4169-007, Porto, Portugal; European Bioinformatics Institute (EMBL-EBI), Welcome Trust Genome Campus, CB10 1SD, Cambridge, United Kingdom.
authors.forename: Nuno A
authors.initials: NA
authors.lastname: Fonseca
authors.affiliation: Michigan State University, East Lansing, Michigan, United States of America.
authors.forename: Amy
authors.initials: A
authors.lastname: Iezzoni
authors.affiliation: Michigan State University, East Lansing, Michigan, United States of America.
authors.forename: Steve
authors.initials: S
authors.lastname: van Nocker
authors.affiliation: Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.
authors.forename: Cristina P
authors.initials: CP
authors.lastname: Vieira
mesh_terms: D005075:Biological Evolution; D017343:Genes, Plant; D027845:Malus / Q000235:genetics*; D010802:Phylogeny; D027861:Prunus / Q000235:genetics*; D060436:Self-Incompatibility in Flowering Plants / Q000235:genetics*