Evidence for the dispersal of a unique lineage from Asia to America and Africa in the sugarcane fungal pathogen Ustilago scitaminea

Raboin Louis-Marie, Selvi Athiappan, Oliveira Karine Miranda, Paulet Florence, Calatayud Caroline, Zapater Marie-Françoise, Brottier Philippe, Luzaran Rosalyn, Garsmeur Olivier, Carlier Jean, D'Hont Angélique. 2007. Evidence for the dispersal of a unique lineage from Asia to America and Africa in the sugarcane fungal pathogen Ustilago scitaminea. Fungal Genetics and Biology, 44 (1) : 64-76.

https://doi.org/10.1016/j.fgb.2006.07.004

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Résumé : 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. © 2006 Elsevier Inc. All rights reserved.

Mots-clés Agrovoc : Ustilago scitaminea, Saccharum officinarum, microsatellite, variation génétique, génétique des populations, descendance, outbreeding, autofécondation forcée, structure de la population, lignée

Mots-clés géographiques Agrovoc : Afrique, Amériques, Asie

Classification Agris : H20 - Maladies des plantes

Champ stratégique Cirad : Axe 1 (2005-2013) - Intensification écologique

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