How diverse is the Ralstonia solanacearum species complex in the South-West lndian Ocean islands?

Yahiaoui Noura, Ravelomanantsoa Santatra, Cheron Jean-Jacques, Chesneau Thomas, Brutus Samuel, Petrousse Bobb, Benimadhu S., Jeetah Rajan, Azali Hamza Abdou, Jaufeerally-Fakim Yasmina, Cottineau Jean Sébastien, Costet Laurent, Robene Isabelle, Hostachy Bruno, Guérin Fabien, Cellier Gilles, Prior Philippe, Poussier Stéphane. 2016. How diverse is the Ralstonia solanacearum species complex in the South-West lndian Ocean islands?. In : 12èmes Rencontres Plantes-Bactéries - Book of Abstracts. SFP, INRA, CNRS. Paris : SFP, 94. Rencontres Plantes-Bactéries. 12, Aussois, France, 11 Janvier 2016/15 Janvier 2016.

Résumé : Ralstonia solanocearum is a species complex (Rssc), distributed worldwide and economically destructive. This soilborne bacterial plant pathogen encompasses an unusually wide host range. The pathogen invades the roots and coloniz.es the xylem vessels causing bacterial wilt (BW) diseases. Four phylogenetic groups called phylotypes structured the Rssc that relates to their geographic origin of evolution: phylotype I (Asia), phylotype II (America), phylotype III (Africa), and phylotype IV (Indonesia-Japan). In the South-West Indian Ocean (SWIO) islands, although R solanocearum is regularly reported, no recent data is available about its genetic diversity and structure. Our main objectives are then to get a significant collection of R.solanacearum strains to thoroughly analyze the genetic diversity of the strains; characterize the evolutionary forces that shape populations; and evaluate genetic resources for resistance to BW. Presently, 2971 R.solanocearum strains have been collected mainly from Solanaceae: Madagscar* (n=1224), Reunion (n=F789), Mauritius (n=693), Mayotte (n=166), Seychelles (n=92), and Comoros (n=5, to be completed). A preliminary broad molecular typing was done using the multiplex PCR (Fegan and Prior 2005)**, showing 46.6% of phylotype I, 42.3% of phylotype II, 11% of phylotype III, and 0.1% of phylotype IV. A selection of 126 strains that covered the geographic and host diversity was organized to assess phylogenetic relationships. Maximum Likelihood tree (PhyML) was performed on the partial endoglucanase (egl) amplification, along with a set of 1 OO international reference strains. Further characterizations are ongoing through a MLSA scheme based on partial amplification of 6 genes; gdhA, mutS, adK, leuS, rplB and gyrB. This is the first report of a large scale survey in the SWIO. Surprisingly we showed that phylotype I-31 is mainly represented and found in every prospected territory in the SWIO. Also Phylotype IV was first described in Mauritius.

Classification Agris : H20 - Maladies des plantes
P34 - Biologie du sol

Auteurs et affiliations

• Yahiaoui Noura, CIRAD-BIOS-UMR PVBMT (REU)
• Ravelomanantsoa Santatra, CIRAD-BIOS-UMR PVBMT (REU)
• Cheron Jean-Jacques, 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)
• Azali Hamza Abdou, INRAPE (COM)
• Jaufeerally-Fakim Yasmina, University of Mauritius (MUS)
• Cottineau Jean Sébastien, ARMEFLHOR (REU)
• Costet Laurent, CIRAD-BIOS-UMR PVBMT (REU) ORCID: 0000-0003-3199-2885
• Robene Isabelle, CIRAD-BIOS-UMR PVBMT (REU)
• Hostachy Bruno, ANSES-LSV (REU)
• Guérin Fabien, Université de la Réunion (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/587129/)

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