title: Self-incompatibility in Brassicaceae: identification and characterization of SRK-like sequences linked to the S-locus in the tribe Biscutelleae.
abstract: Self-incompatibility (SI) is a genetic system that prevents self-fertilization in many Angiosperms. Although plants from the Brassicaceae family present an apparently unique SI system that is ancestral to the family, investigations at the S-locus responsible for SI have been mostly limited to two distinct lineages (Brassica and Arabidopsis-Capsella, respectively). Here, we investigated SI in a third deep-branching lineage of Brassicaceae: the tribe Biscutelleae. By coupling sequencing of the SI gene responsible for pollen recognition (SRK) with phenotypic analyses based on controlled pollinations, we identified 20 SRK-like sequences functionally linked to 13 S-haplotypes in 21 individuals of Biscutella neustriaca and 220 seedlings. We found two genetic and phylogenetic features of SI in Biscutelleae that depart from patterns observed in the reference Arabidopsis clade: (1) SRK-like sequences cluster into two main phylogenetic lineages interspersed within the many SRK lineages of Arabidopsis; and (2) some SRK-like sequences are transmitted by linked pairs, suggesting local duplication within the S-locus. Strikingly, these features also were observed in the Brassica clade but probably evolved independently, as the two main SRK clusters in Biscutella are distinct from those in Brassica. In the light of our results and of what has been previously observed in other Brassicaceae, we discuss the ecological and evolutionary implications on SI plant populations of the high diversity and the complex dominance relationships we found at the S-locus in Biscutelleae.
authors.affiliation: Institut de Biologie Intégrative et des Systèmes, Département de Biologie, PROTEO, Pavillon Charles-Eugène-Marchand, 1030 avenue de la Médecine - Université Laval - Québec (QC) G1V 0A6, Canada Institut des Sciences de l'Évolution UMR 5554, CNRS, Université Montpellier 2, Place Eugène Bataillon, C.C. 065 - 34095 Montpellier cedex 05, France jean-baptiste.leducq.1@ulaval.ca.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Leducq
authors.affiliation: Institut des Sciences de l'Évolution UMR 5554, CNRS, Université Montpellier 2, Place Eugène Bataillon, C.C. 065 - 34095 Montpellier cedex 05, France Laboratoire Génétique et Evolution des Populations Végétales, CNRS UMR 8198, Université Lille1, F-59655 Villeneuve d'Ascq cedex, France.
authors.forename: Célia C
authors.initials: CC
authors.lastname: Gosset
authors.affiliation: Laboratoire Génétique et Evolution des Populations Végétales, CNRS UMR 8198, Université Lille1, F-59655 Villeneuve d'Ascq cedex, France.
authors.forename: Rita
authors.initials: R
authors.lastname: Gries
authors.affiliation: Laboratoire Génétique et Evolution des Populations Végétales, CNRS UMR 8198, Université Lille1, F-59655 Villeneuve d'Ascq cedex, France.
authors.forename: Kevin
authors.initials: K
authors.lastname: Calin
authors.affiliation: Laboratoire Génétique et Evolution des Populations Végétales, CNRS UMR 8198, Université Lille1, F-59655 Villeneuve d'Ascq cedex, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Schmitt
authors.affiliation: Laboratoire Génétique et Evolution des Populations Végétales, CNRS UMR 8198, Université Lille1, F-59655 Villeneuve d'Ascq cedex, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Castric
authors.affiliation: Laboratoire Génétique et Evolution des Populations Végétales, CNRS UMR 8198, Université Lille1, F-59655 Villeneuve d'Ascq cedex, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Vekemans
mesh_terms: D019943:Amino Acid Substitution; D019607:Brassicaceae / Q000145:classification / Q000235:genetics*; D016000:Cluster Analysis; D003433:Crosses, Genetic; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D056426:Genetic Loci; D014644:Genetic Variation; D006239:Haplotypes; D010641:Phenotype; D010802:Phylogeny; D054817:Pollination / Q000235:genetics*; D011110:Polymorphism, Genetic; D056510:Position-Specific Scoring Matrices; D012641:Selection, Genetic; D057945:Self-Fertilization / Q000235:genetics*
keywords: Biscutelleae; SRK; controlled crosses; dominance/recessivity; genetics of sex; self-incompatibility