Diversity and population structure of the Ralstonia solanacearum species complex in the South-West Indian Ocean islands

Yahiaoui Noura, Cheron Jean-Jacques, Dianzinga Niry Tiana, Chesneau Thomas, Brutus Samuel, Petrousse Bobb, Benimadhu S., Jeetah Rajan, Hamza Abdou Azali, Jaufeerally-Fakim Yasmina, Félicité Jérôme, Cottineau Jean Sébastien, Fillâtre Jacques, Hostachy Bruno, Cellier Gilles, Prior Philippe, Poussier Stéphane. 2016. Diversity and population structure of the Ralstonia solanacearum species complex in the South-West Indian Ocean islands. In : Book of abstracts of the 6th International Bacterial Wilt Symposium. INRA. Toulouse : INRA, Résumé, p. 46. International Bacterial Wilt Symposium. 6, Toulouse, France, 3 Juillet 2016/7 Juillet 2016.

Résumé : The Ralstonia solanacearum species complex (Rssc) encompasses strains that are highly destructive worldwide on a wide hast range. This soilborne bacterial plant pathogen invades the roots and colonizes the xylem vessels causing bacterial wilt (BW) diseases. Strains are distributed into four phylogenetic groups, called phylotypes, differing in geographical origin of the strains: phylotype I (Asia), phylotype II (America), phylotype III (Africa) and phylotype IV (Australia - lndonesia - Japan). Each phylotype is subdivided into sequevars based on partial sequencing of the endoglucanase (egl) gene (Fegan and Prior, 2005). In the South-West lndian Ocean (SWIO) islands, although the Rssc is regularly reported no recent data is available about its genetic diversity and population structure. To thoroughly analyze the genetic diversity of the Rssc in the SWIO, we collected a significant collection of Rssc strains mainly from Solanaceae: Reunion (n=789, 41 sites), Mauritius (n=785, 30 sites), Rodrigues (n=S1, 3 sites), Mayotte (n=166, 24 sites), Seychelles (n=92, 9 sites) and Comoros (n=S, to be completed). Using the Multiplex-PCR (Fegan and Prior, 2005), we revealed that the four phylotypes are present with variable distribution depending on the SWIO islands and variable proportions: phylotype 1 (86.7%), phylotype II (9.7%), phylotype Ill (3.5%) and two strains from phylotype IV (0.1%). Partial egl sequencing based on a selection of strains that covered the geographic and hast diversity showed the unexpected overrepresentation of one sequevar (1-31). Further characterizations are ongoing through (i) a MLSA/MLST (Multilocus sequence analysis/typing) based on partial amplification of 7 genes (gdhA, mutS, adK, feus, rp/B, gyrB, and egl) and (ii) the development of a new MLVA (Multilocus variable number of tandem repeat analysis) scheme. Results of bath approaches will be discussed du ring the presentation.

Classification Agris : H20 - Maladies des plantes

Auteurs et affiliations

• Yahiaoui Noura, CIRAD-BIOS-UMR PVBMT (REU)
• Cheron Jean-Jacques, CIRAD-BIOS-UMR PVBMT (REU)
• Dianzinga Niry Tiana, CIRAD-BIOS-UMR PVBMT (REU)
• Chesneau Thomas, Lycée agricole de Coconi (MYT)
• Brutus Samuel, Seychelles Agricultural Agency (SYC)
• Petrousse Bobb, Seychelles Agricultural Agency (SYC)
• Benimadhu S., FAREI (MUS)
• Jeetah Rajan, FAREI (MUS)
• Hamza Abdou Azali, Université des Comores (COM)
• Jaufeerally-Fakim Yasmina, University of Mauritius (MUS)
• Félicité Jérôme, Commision of Agriculture (MUS)
• Cottineau Jean Sébastien, ARMEFLHOR (REU)
• Fillâtre Jacques, ARMEFLHOR (REU)
• Hostachy Bruno, ANSES-LSV (REU)
• Cellier Gilles, ANSES-LSV (REU)
• Prior Philippe, CIRAD-BIOS-UMR PVBMT (REU)
• Poussier Stéphane, Université de la Réunion (REU)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/587145/)

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