title: Evidence for the dispersal of a unique lineage from Asia to America and Africa in the sugarcane fungal pathogen Ustilago scitaminea.
abstract: The basidiomycete Ustilago scitaminea Sydow, which causes sugarcane smut disease, has been spreading throughout Africa and America since the 1940s. The genetic diversity and structure of different populations of this fungus worldwide was investigated using microsatellites. A total of 142 single-teliospore were isolated from 77 distinct whips (sori) collected in 15 countries worldwide. Mycelium culture derived from on generation of selfing of these single teliospores were analysed for their polymorphisms at 17 microsatellite loci. All these strains but one were homozygous at all loci, indicating that selfing is likely the predominant reproductive mode of U. scitaminea. The genetic diversity of either American or African U. scitaminea populations was found to be extremely low and all strains belong to a single lineage. This lineage was also found in some populations of Asia, where most U. scitaminea genetic diversity was detected, suggesting that this fungal species originated from this region. The strong founder effect observed in U. scitaminea African and American populations suggests that the fungus migrated from Asia to other continents on rare occasions through movement of infected plant material.
authors.affiliation: CIRAD (Centre de coopération internationale en recherche agronomique pour le développement), UMR PVBMT, Pôle de Protection des Plantes, Ligne Paradis, 97410 Saint-Pierre, Réunion, France.
authors.forename: Louis-Marie
authors.initials: LM
authors.lastname: Raboin
authors.forename: Athiappan
authors.initials: A
authors.lastname: Selvi
authors.forename: Karine Miranda
authors.initials: KM
authors.lastname: Oliveira
authors.forename: Florence
authors.initials: F
authors.lastname: Paulet
authors.forename: Caroline
authors.initials: C
authors.lastname: Calatayud
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: Zapater
authors.forename: Philippe
authors.initials: P
authors.lastname: Brottier
authors.forename: Rosalyn
authors.initials: R
authors.lastname: Luzaran
authors.forename: Olivier
authors.initials: O
authors.lastname: Garsmeur
authors.forename: Jean
authors.initials: J
authors.lastname: Carlier
authors.forename: Angélique
authors.initials: A
authors.lastname: D'Hont
mesh_terms: D000349:Africa; D000569:Americas; D001208:Asia; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats / Q000235:genetics; D010802:Phylogeny; D031786:Saccharum / Q000382:microbiology*; D013172:Spores, Fungal / Q000502:physiology; D014588:Ustilago / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology