Santatra Ravelomanantsoa

CENRADERU/FOFIFA National Center of Applied Research for Rural Development · Department of Agricultural Research

The Ralstonia solanacearum species complex (RSSC), composed of three species and four phylotypes, are globally distributed soil-borne bacteria with a very broad host range. In 2009, a devastating potato bacterial wilt outbreak was declared in the central highlands of Madagascar, which reduced the production of vegetable crops including potato, eggp...

The Ralstonia solanacearum species complex (RSSC) causes bacterial wilt diseases, which affect a wide range of plant hosts, including Solanaceae, and is of major economic importance. Point-of-care (POC) techniques such as loop-mediated isothermal amplification (LAMP) enable the rapid and sensitive detection of plant pathogens and can be deployed di...

Bacterial wilt caused by the Ralstonia solanacearum species complex (RSSC) is a major threat to vegetable crops in Madagascar. For more effective disease management, surveys were carried out in the main vegetable production areas of the country, leading to the collection of 401 new RSSC isolates. Phylogenetic assignment of the isolates revealed a h...

Cassava is one of the most important staple crops in Africa and its production is seriously damaged by viral diseases. In this study, we identify for the first time and characterize the genome organization of novel ampeloviruses infecting cassava plants in diverse geographical locations using three high-throughput sequencing protocols [Virion-Assoc...

The Ralstonia solanacearum species complex (RSSC) is a highly diverse cluster of bacterial strains found worldwide, many of which are destructive and cause bacterial wilt (BW) in a wide range of host plants. In 2009, potato production in Madagascar was dramatically affected by several BW epidemics. Controlling this disease is critical for Malagasy...

Split graphs of multilocus sequence analysis of the global collection (C3) for the seven loci (gdhA, gyrB, rplB, leuS, adk, mutS, and egl) and the data set of the concatenated sequences. Strains from each phylotype (I, IIA, IIB, III, and IV) of the RSSC are highlighted in blue, light green, dark green, red and gray, respectively.

RSSC strains used in this study and corresponding phylogenetic and genotyping data.

Description of MLST loci, corresponding oligonucleotide primers, and PCR conditions.

Genetic properties of the loci used in MLSA for each phylotype of the SWIO (C1) and the worldwide (C2) RSSC collections.

GenBank accession numbers for the partial sequences of seven loci used in this study. New accession numbers of sequences are in bold.

Substitution models of the seven genes studied using Jmodeltest 2.

Comparison between the seven genes (gdhA, gyrB, rplB, leuS, adk, mutS, and egl) and the concatenated-genes trees generated by the congruency Index Icong values. Icong, p-value, and MAST were indicated in this table.

Variation in number of records for RSSC hosts in the SWIO area. Letters above bars represent groups of hosts (a–d) calculated by Chi-Square test by R software. Phylotype I (blue), phylotype II (orange), phylotype III (red), and phylotype IV (gray).

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 gen...

Nous avons exploré la diversité génétique du complexe d’espèces Ralstonia solanacearum (ceRs) pour caractériser et comprendre les graves épidémies de flétrissement bactérien qui sévissent à Madagascar. Une large collection de souches (n = 1224; 75 sites) est constituée. Les souches sont assignées aux phylotypes I, III, et la grande majorité associé...

Nous avons exploré la diversité génétique du complexe d'espèces Ralstonia solanacearum (ceRs) pour caractériser et comprendre les graves épidémies de flétrissement bactérien qui sévissent à Madagascar. Une large collection de souches (n=1224; 75 sites) est constituée. Les souches sont assignées aux phylotypes I, III, et la grande majorité associée...

Reliable genotyping that provides an accurate description of diversity in the context of pathogen emergence is required for the establishment of strategies to improve disease management. MultiLocus variable number tandem repeat analysis (MLVA) is a valuable genotyping method. It can be performed at small evolutionary scales where high discriminator...

An illustration of a VNTR loci sequence analysis: alignment of RS3L27 repeats and flanking sequences in four unrelated strains using Muscle RS3L27 is a TR locus with TR units that are 8 bp in length. The lengths of the flanking regions are conserved. The number of TRs differs between different isolates, suggesting that polymorphisms based on size d...

HACs of related and unrelated isolates in the three populations of RSSC isolates (P35, P20, P17) and the collection C65genotyped over 16 loci Each circle represents the relationship between the numbers of haplotypes (g) detected and the number of loci sampled (n). The radius of each circle is equal to the ratio between different combinations of n l...

Visualization of the variability in TR patterns found for RS3L20 in strain CMR15 Mean identity of 51% was observed between repeat units.

Strains of RSSC belonging to phylotype III used in this study and corresponding genotyping data (A) Isolates included in collection P35. (B) Isolates included in collection P20. (C) Isolates included in collection P17. Collection C65 includes all isolates used in this study (n = 65). nd: not determined. AEZ: Agro-ecological zones of Cameroon from w...

Description of TR loci, corresponding oligonucleotide primers and multiplex combinations, and PCR conditions used in this study (A) Nomenclature of VNTR locus was as follows: marker alias_replicon of origin (ch: chromosome or mp: megaplasmid)_start physical position expressed in kilobases in the CMR15 genome_TR unit size (bp)_ amplicon size in the...

Muscle alignments of RS2AL03, RS2LB23, RS1L09, and RS3L18 (A) The consensus repeat pattern in the RS2AL03 locus (found on the genome of strain CFBP2957, which belongs to phylotype IIA) is CGGACCTCGCACTT. TRs are not present in the CMR15 genome (a reference strain belonging to phylotype III). (B) The consensus pattern in the RS2LB23 locus (found on...

GenBank accession numbers for the partial sequences of MLST loci used in this study Accession numbers of sequences retrieved from GenBank are in italics. Accession numbers of new sequences are in bold.

Description of MLST loci, corresponding oligonucleotide primers, and PCR conditions (A) Rank according to location within the physical map of the CMR15 genome. Accession numbers: chromosome ( FP885895) and megaplasmid ( FP885896) (B) defined based on the CMR15 genome F: F primer; R: R primer.

Optimal combinations of TR markers used to discriminate all haplotypes from the four collections used (A) The number of possible combinations for each set of loci are given in parentheses. (B) There are 120 possible combinations if 2 of the 16 loci are used, 560 possible combinations if 3 of the 18 loci are used, and so forth. The underlined combin...

Diversity in the South-West Indian Ocean. Surveys, phylotype analysis and phylogenetic tree by egl sequencing.

Endophytic microorganisms inhabit living plant tissues without causing disease symptoms. They may develop various interactions with the plant host. In this purpose, endophytes can also synthesize some bioactive products identical to the one synthesized by the plant host. This data will be proved to Eugenia jambolana to which Madeglucyl®, an antidia...

La culture de blé et sa consommation en nature ont constitué une tradition séculaire dans le mode de vie économique et social des populations rurales, notamment dans la région du Vakinankaratra. D’autre part, les citadins ont coutume à recourir dans ses habitudes alimentaires quotidiennes aux produits dérivés semi-finis à finis du blé (farine, pain...

Contexte L’éveil des paysans et notamment des opérateurs potentiels pour la relance de la culture du blé et de triticale évolue au train où progressent les activités de promotion de la culture par FIFAMANOR via le développement et la diffusion des variétés performantes, la production et la vente de semences améliorées. Par la même, les investigatio...

Les paysans s’adonnent davantage à la culture du blé qu’on constate aujourd’hui une remarquable expansion des terrains emblavés dans la région du Vakinankaratra, notable en contre saison. Manifestement, la valeur de cette culture est perçue dans la vie paysanne. En effet, étant un aliment complet, le blé se trouve très apprécié par les travailleurs...

La campagne 2006 pour le blé et le triticale a été généralement caractérisée par un déficit hydrique : manque de précipitations en saison pluviale, une insuffisance en alimentation hydrique en contre saison, notamment vers la fin du cycle végétatif du blé, où l’alimentation hydrique et les précipitations sont très importantes pour le remplissage de...

Factors that could cause exceedance of maximum allowable limit of SO2 and that could affect the quality of litchi have been highlighted. Changes in the SO2 content in the pericarp and the aril are correlated with the peel integrity. Desiccation, senescence from the pericarp and peel injury are identified as major constraint affecting the pericarp p...

Ralstonia solanacearum is the causative agent of wilt disease in plants, which constitutes a severe problem to agricultural crops, particularly for potato production in Madagascar. The present study focuses on the isolation, in vitro and in vivo assays of potential rhizospheric and endophytic bacteria associated with healthy potato plant, capable t...

Bacterial wilt, caused by Ralstonia solanacearum (Rs) (Smith) Yabuuchi et al., is one of the most important diseases of potato crops worldwide, including Madagascar. From the literature, strains of Rs phylotypes III or I were pathogenic to Solanaceae in the highlands potato areas (1,2). From years these strains were managed through the deployment o...

La qualité requise du blé dépend de son utilisation. Le plus souvent, le rendement pour le producteur de blé ; la qualité des protéines pour les industries de transformation. Cependant, ces deux traits présentent des corrélations négatives. Le rendement en grains et la qualité des protéines sont alors deux critères décisifs à combiner dans la sélec...

Potential for profitable wheat production in Madagascar (Poster #1) Wheat cultivation is practiced at high altitudes in Madagascar. It is produced three times per year in broad lands: in the rainy season on hillsides, when water level decreases on bank lands and during the off-season on plains and in valleys after rice. FIFAMANOR, a rural develop...

(Poster #1) Potential for profitable wheat production in Madagascar : Wheat cultivation is practiced at high altitudes in Madagascar. It is produced three times per year in broad lands: in the rainy season on hillsides, when water level decreases on bank lands and during the off-season on plains and in valleys after rice. FIFAMANOR, a rural develo...