Biologie des populations du complexe d'espèces Ralstonia solanacearum appliquée à l'épidémiologie de la bactériose vasculaire de la pomme de terre à Madagascar

Abstract : This thesis is exploring genetic diversity, population structure and molecular epidemiology of the Ralstonia solanacearum species complex (Rssc) causing potato bacterial wilt outbreaks in Madagascar. We characterized a large collection of strains (n=1224; 75 sites) collected from potato production areas. Surprisingly, the large outbreaks were associated with IIB-1 strains (Brown rot) while a few were associated with phylotypes I and III. This is the first report of phylotype IIB-1 in Madagascar. The IIB-1 strains were genotyped based on MLVA (RS2-MLVA9). And Malagasy phylotype IIB-1 clustered with worldwide distributed strains. Fine scale genetic investigation suggested three clonal populations that were introduced and spread through latently infected tuber-seeds. Phylotype III strains were genotyped with the highly discriminatory RS3-MLVA16 scheme we developed. Genetic population analyses revealed a high genetic diversity within phylotype III strains that geographically structured into 11 clonal populations. This support the endemic character of the phylotype III population in Madagascar and suggests no transmission with potato tubers. Malagasy strains were distinct from continental African strains. A clear-cut epidemiological profile is shown between IIB-1 and III strains. Genetically, no bacterial wilt resistance properties were shown for the most popular Malagasy potato cultivars, except two cultivars: 720118 and 800934 that showed strong resistance to phylotype I-31 strain that are predominantly distributed in the Indian Ocean. This study offered tool to genotype phylotype III strains and gives an insights into population structure and epidemiology of the Rssc.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01432701
Contributor : Abes Star <>
Submitted on : Tuesday, December 4, 2018 - 5:11:07 PM
Last modification on : Monday, September 2, 2019 - 9:41:30 AM

File

2016LARE0017_SRavelo_dif.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01432701, version 2

Citation

Santatra Herilalaina Ravelomanantsoa. Biologie des populations du complexe d'espèces Ralstonia solanacearum appliquée à l'épidémiologie de la bactériose vasculaire de la pomme de terre à Madagascar. Biologie végétale. Université de la Réunion, 2016. Français. ⟨NNT : 2016LARE0017⟩. ⟨tel-01432701v2⟩

Share

Metrics

Record views

221

Files downloads

535