1. Genetic Diversity of the Ralstonia solanacearum Species Complex in the Southwest Indian Ocean Islands
- Author
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Yahiaoui, Noura, Chéron, Jean-Jacques, Ravelomanantsoa, Santatra, Hamza, Azali A., Petrousse, Bobb, Jeetah, Rajan, Jaufeerally-Fakim, Yasmina, Félicité, Jérôme, Fillâtre, Jacques, Hostachy, Bruno, Guérin, Fabien, Cellier, Gilles, Prior, Philippe, Poussier, Stéphane, Peuplements végétaux et bioagresseurs en milieu tropical (UMR PVBMT), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université de La Réunion (UR), Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES), Centre National de Recherche Appliquée au Développement Rural (FOFIFA), Institut National de la Recherche pour l'Agriculture, la Pêche et l'Environnement, Seychelles Agricultural Agency, Food and Agricultural Research and Extension Institute, University of Mauritius, Commission of Agriculture, Association Réunionnaise pour la Modernisation de l’Economie Fruitière, Légumière et HORticole (ARMEFLHOR), Agropolis Fondation : 1403-011, ANR-10-LABX-0001-01, European Union: European regional development fund (ERDF), Conseil Regional de La Reunion, Centre de Cooperation Internationale en Recherche agronomique pour le Developpement (CIRAD), ANSES, CIRAD, ANR-10-LABX-0001,AGRO,Agricultural Sciences for sustainable Development(2010), Association Réunionnaise pour la Modernisation de l’Economie Fruitière Légumière et HORticole, Centre National de la Recherche Appliquée au Développement Rural, UMR Peuplement Végétaux et Bioagresseurs en Milieu Tropical (UMR PVBMT - INRA), Institut National de la Recherche Agronomique (INRA), and ANR-10-LABX-0001/10-LABX-0001,AGRO,Agricultural Sciences for sustainable Development(2010)
- Subjects
MLSA ,Phylogénie ,Polymorphisme génétique ,Plant Science ,Variation génétique ,Génétique des populations ,[SDV.BV]Life Sciences [q-bio]/Vegetal Biology ,Surveillance épidémiologique ,Original Research ,H20 - Maladies des plantes ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,clonal complex ,Ralstonia solanacearum species complex ,P34 - Biologie du sol ,genetic diversity ,Agricultural sciences ,Épidémiologie ,Enquête pathologique ,Southwest Indian Ocean ,epidemiology ,diversité génétique ,Ralstonia solanacearum ,océan indien ,Sciences agricoles ,MLST - Abstract
Epidemiological surveillance of plant pathogens based on genotyping methods is mandatory to improve disease management strategies. In the Southwest Indian Ocean (SWIO) islands, bacterial wilt (BW) caused by the Ralstonia solanacearum species complex (RSSC) is hampering the production of many sustainable and cash crops. To thoroughly analyze the genetic diversity of the RSSC in the SWIO, we performed a wide sampling survey (in Comoros, Mauritius, Reunion, Rodrigues, and Seychelles) that yielded 1,704 isolates from 129 plots, mainly from solanaceous crops. Classification of the isolates to the four major RSSC phylogenetic groups, named phylotypes, showed that 87% were phylotype I, representing the most prevalent strain in each of the SWIO islands. Additionally, 9.7% were phylotype II, and 3.3% were phylotype III; however, these isolates were found only in Reunion. Phylotype IV (2 isolates), known to be restricted to Indonesia-Australia-Japan, was reported in Mauritius, representing the first report of this group in the SWIO. Partial endoglucanase (egl) sequencing, based on the selection of 145 isolates covering the geographic and host diversity in the SWIO (also including strains from Mayotte and Madagascar), revealed 14 sequevars with Reunion and Mauritius displaying the highest sequevar diversity. Through a multilocus sequence analysis (MLSA) scheme based on the partial sequencing of 6 housekeeping genes (gdhA, gyrB, rplB, leuS, adk, and mutS) and 1 virulence-associated gene (egl), we inferred the phylogenetic relationships between these 145 SWIO isolates and 90 worldwide RSSC reference strains. Phylotype I was the most recombinogenic, although recombination events were detected among all phylotypes. A multilocus sequence typing (MLST) scheme identified 29 sequence types (STs) with variable geographic distributions in the SWIO. The outstanding epidemiologic feature was STI-13 (sequevar I-31), which was overrepresented in the SWIO and obviously reflected a lineage strongly adapted to the SWIO environment. A goeBURST analysis identified eight clonal complexes (CCs) including SWIO isolates, four CCs being geographically restricted to the SWIO, and four CCs being widespread beyond the SWIO. This work, which highlights notable genetic links between African and SWIO strains, provides a basis for the epidemiological surveillance of RSSC and will contribute to BW management in the SWIO.
- Published
- 2017
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