title: Wheat alleles introgress into selfing wild relatives: empirical estimates from approximate Bayesian computation in Aegilops triuncialis.
abstract: Extensive gene flow between wheat (Triticum sp.) and several wild relatives of the genus Aegilops has recently been detected despite notoriously high levels of selfing in these species. Here, we assess and model the spread of wheat alleles into natural populations of the barbed goatgrass (Aegilops triuncialis), a wild wheat relative prevailing in the Mediterranean flora. Our sampling, based on an extensive survey of 31 Ae. triuncialis populations collected along a 60 km × 20 km area in southern Spain (Grazalema Mountain chain, Andalousia, totalling 458 specimens), is completed with 33 wheat cultivars representative of the European domesticated pool. All specimens were genotyped with amplified fragment length polymorphism with the aim of estimating wheat admixture levels in Ae. triuncialis populations. This survey first confirmed extensive hybridization and backcrossing of wheat into the wild species. We then used explicit modelling of populations and approximate Bayesian computation to estimate the selfing rate of Ae. triuncialis along with the magnitude, the tempo and the geographical distance over which wheat alleles introgress into Ae. triuncialis populations. These simulations confirmed that extensive introgression of wheat alleles (2.7 × 10(-4) wheat immigrants for each Ae. triuncialis resident, at each generation) into Ae. triuncialis occurs despite a high selfing rate (Fis ≈ 1 and selfing rate = 97%). These results are discussed in the light of risks associated with the release of genetically modified wheat cultivars in Mediterranean agrosystems.
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, Lausanne, CH-1015, Switzerland.
authors.forename: Mila
authors.initials: M
authors.lastname: Pajkovic
authors.forename: Sylvain
authors.initials: S
authors.lastname: Lappe
authors.forename: Rachel
authors.initials: R
authors.lastname: Barman
authors.forename: Christian
authors.initials: C
authors.lastname: Parisod
authors.forename: Samuel
authors.initials: S
authors.lastname: Neuenschwander
authors.forename: Jerome
authors.initials: J
authors.lastname: Goudet
authors.forename: Nadir
authors.initials: N
authors.lastname: Alvarez
authors.forename: Roberto
authors.initials: R
authors.lastname: Guadagnuolo
authors.forename: François
authors.initials: F
authors.lastname: Felber
authors.forename: Nils
authors.initials: N
authors.lastname: Arrigo
mesh_terms: D000483:Alleles; D054458:Amplified Fragment Length Polymorphism Analysis; D001499:Bayes Theorem; D018744:DNA, Plant / Q000235:genetics; D051456:Gene Flow; D005828:Genetics, Population; D006824:Hybridization, Genetic; D008957:Models, Genetic; D006109:Poaceae / Q000235:genetics*; D013030:Spain; D014908:Triticum / Q000235:genetics*
chemical_list: D018744:DNA, Plant
keywords: ABC; admixture; autogamy; containment; crop to wild gene flow; transgene escape