title: Evidence for the long-term maintenance of a rare self-incompatibility system in Oleaceae.
abstract: A rare homomorphic diallelic self-incompatibility (DSI) system discovered in Phillyrea angustifolia (family Oleaceae, subtribe Oleinae) can promote the transition from hermaphroditism to androdioecy. If widespread and stable in Oleaceae, DSI may explain the exceptionally high rate of androdioecious species reported in this plant family. Here, we set out to determine whether DSI occurs in another Oleaceae lineage. We tested for DSI in subtribe Fraxininae, a lineage that diverged from subtribe Oleinae c. 40 million yr ago. We explored the compatibility relationships in Fraxinus ornus using 81 hermaphrodites and 25 males from one natural stand and two naturalized populations using intra- and interspecific stigma tests performed on F. ornus and P. angustifolia testers. We uncovered a DSI system with hermaphrodites belonging to one of two self-incompatibility (SI) groups and males compatible with both groups, making for a truly androdioecious reproductive system. The two human-founded populations contained only one of the two SI groups. Our results provide evidence for the evolutionary persistence of DSI. We discuss how its stability over time may have affected transitions to other sexual systems, such as dioecy.
authors.affiliation: Université de Lille - Sciences et Technologies, CNRS, UMR 8198 Evo-Eco-Paleo, F59655, Villeneuve d'Ascq, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Vernet
authors.affiliation: Université de Lille - Sciences et Technologies, CNRS, UMR 8198 Evo-Eco-Paleo, F59655, Villeneuve d'Ascq, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Lepercq
authors.affiliation: Université de Lille - Sciences et Technologies, CNRS, UMR 8198 Evo-Eco-Paleo, F59655, Villeneuve d'Ascq, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Billiard
authors.affiliation: Université de Lille - Sciences et Technologies, CNRS, UMR 8198 Evo-Eco-Paleo, F59655, Villeneuve d'Ascq, France.
authors.forename: Angélique
authors.initials: A
authors.lastname: Bourceaux
authors.affiliation: CEFE-UMR 5175 du CNRS, 1919 route de Mende, 34293, Montpellier Cedex, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Lepart
authors.affiliation: CEFE-UMR 5175 du CNRS, 1919 route de Mende, 34293, Montpellier Cedex, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Dommée
authors.affiliation: Université de Lille - Sciences et Technologies, CNRS, UMR 8198 Evo-Eco-Paleo, F59655, Villeneuve d'Ascq, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Saumitou-Laprade
mesh_terms: D005075:Biological Evolution; D035264:Flowers / Q000235:genetics / Q000502:physiology; D031661:Fraxinus / Q000235:genetics / Q000502:physiology; D029592:Oleaceae / Q000235:genetics / Q000502:physiology*; D012098:Reproduction; D060436:Self-Incompatibility in Flowering Plants
keywords: androdioecy; cryptic dioecy; diallelic self-incompatibility system; naturalized populations; plant mating systems; transgeneric conservation of SI functionality