Papers by Fabrice Lheureux
HAL (Le Centre pour la Communication Scientifique Directe), Dec 8, 2021
Il y a 450 millions d’années, des algues vertes conquirent les terres émergées : elles allaient d... more Il y a 450 millions d’années, des algues vertes conquirent les terres émergées : elles allaient devenir les plantes que nous connaissons. Cette conquête des continents, n’a probablement été rendue possible que par le développement d’une association bénéfique entre les racines des plantes et des champignons. Cette association ancestrale, appelée la mycorhize à arbuscules, est la plus ancienne symbiose mutualiste entre plantes et microorganismes.Cette monographie synthétise les connaissances sur la mycorhize à arbuscules et les services rendus dans les agroécosystèmes, leurs impacts sur les interactions plus larges entre organismes (interactions plante-plante et interactions multi-trophiques plantes-champignons mycorhiziens-bactéries), les liens entre itinéraires de culture et mycorhization. Enfin, elle comporte un focus sur le projet « Mycoagra » qui aborde ces aspects sur le noyer
Recently introduced inter-specific #Musa# hybrids, bred for improved yield and resistance to dise... more Recently introduced inter-specific #Musa# hybrids, bred for improved yield and resistance to diseases, have been found to be widely infected with several Banana streak badnavirus (BSV-Obino I'Ewai (BSV-OI), BSV-Imove (BSV-Im) and BSV-GoId Finger (BSV-Gf) strains), the causal agent of banana streak disease (BSD). One hypothesis suggests that BSD occurrence in these inter-specific hybrids results from activation of corresponding BSV endogenous pararetrovirus sequences (EPRVs) integrated into the Musa genome rather than from external sources of infection. The process of genetic hybridisation and abiotic stress such as micropropagation by #in vitro# culture may be responsible in triggering episomal expression of these BSV integrants. In order to test the first hypothesis we carried out a genetic analysis of banana streak disease incidence in a F1 triploid (AAB) population produced by hybridisation between virus- and disease-free #M. balbisiana# Pisang Klutug Wulung PKW (BB diploid) ...
Banana streak virus (BSV) sequences are integrated in the nuclear genome of Musa species. Some of... more Banana streak virus (BSV) sequences are integrated in the nuclear genome of Musa species. Some of these BSV endogenous pararetrovirus (BSV EPRVs), restricted to Musa balbisiana chromosome (noted B), can give rise to infectious episomal BSV particles upon stress conditions such as inter-specific genetic crosses. A genetic analysis of BSV incidence in a F1 triploid (Musa AAB) population produced by inter-specific hybridisation between virus-free diploid M. balbisiana (BB) and tetraploid M. acuminata (AAAA) parents showed that half of the F1 progeny expressed BSV particles. A PCR-based analysis determined that BSV EPRVs were restricted to the M. balbisiana genome only. A bulk AFLP segregant analysis revealed seven AFLP markers co-segregating with the presence of BSV infection and three with the absence of BSV infection. All of them were restricted to the M. balbisiana genome. Analysis of the segregation of these markers using a test-cross configuration allowed the construction of a gen...
Inter-specific hybrids have, in the past few years, been shown to express symptom of Banana strea... more Inter-specific hybrids have, in the past few years, been shown to express symptom of Banana streak disease (BSD) that could not have originated from external sources of Banana streak virus (BSV). It was hypothesised that infections arose instead through a complex recombination pattern from viral sequences integrated into the Musa genome called BSV-OL Endogenous Pararetrovirus Sequences EPRVs. The aim of our study was to search for the genetic factor that activates EPRV expression during genetic cross hybridisation of two interspecific crosses - PKW (BB) x IDN 110 4x (AAAA) and P. batu (BB) x P. pipit 4x (AAAA)-. The study of the two FI progeny showed Mendelian segregation of the disease with half of the hybrids containing virus. The observation of BSV strain 01 EPRV segregation occurs in a homozygous state at Musa balbisiana genome only. Ten AFLP markers were selected in female M. balbisiana parents. The segregation analysis allowed a genetic map of the locus responsible of disease ...
Des fragments de genome de pararetrovirus ont ete observes, integres au genome de leur plante hot... more Des fragments de genome de pararetrovirus ont ete observes, integres au genome de leur plante hote. Rien n'est actuellement connu sur l'origine de ces fragments; les pararetrovirus n'ont besoin a aucune etape de leur multiplication d'integrer le genome hote. La totalite du genome du virus de la mosaique du bananier -Banana streak badnavirus- est presente par fragments dans les chromosomes d'une des deux especes de bananier utilisees pour la creation d'hybrides interspecifiques: #Musa balbisiana#. Ces fragments endogenes sont suspectes sous l'action de stress comme la culture #in vitro# ou les croisements genetiques d'etre a l'origine de particules virales pathogenes. Nos travaux conduits sur l'expression du BSV au cours de la CIV ont montre l'effet determinant de l'etape "proliferation" sur l'apparition des particules virales a partir d'un hybride interspecifique sain possedant les sequences virales endogenes. Ceux co...
Des sequences virales de Banana streak virus (BSV) sont integrees dans le genome des bananiers. C... more Des sequences virales de Banana streak virus (BSV) sont integrees dans le genome des bananiers. Certaines de ces sequences endogenes BSV, nommees endogenous pararetrovirus EPRV, limitees au chromosome de l'espece Musa balbisiana (note B) sont a l'origine de particules virales infectieuses apres des stress biotiques et abiotiques comme ceux resultant de croisements genetiques interspecifiques. L'analyse genetique de l'incidence du BSV sur une population FI triploide (AAB) issue du croisement interspecifique entre des parents sains diploide M. balbisiana (BB) et tetraploide M. acuminata (AAAA) montre une segregation mendelienne de l'expression de la maladie puisque la moitie de la descendance presente des particules virales de type BSV. Une analyse PCR du croisement utilisant des amorces specifique du BSV a montre que les EPRV BSV etaient restreintes au seul genome M. balbisiana. Des marqueurs moleculaires lies a la presence ou a l'absence de virus episomal ont...
Frontiers in Plant Science, 2017
Plant architecture is crucial for rapeseed yield and is determined by plant height (PH), branch i... more Plant architecture is crucial for rapeseed yield and is determined by plant height (PH), branch initiation height (BIH), branch number (BN) and leaf and inflorescence morphology. In this study, we measured three major factors (PH, BIH, and BN) in a panel of 333 rapeseed accessions across 4 years. A genome-wide association study (GWAS) was performed via Q + K model and the panel was genotyped using the 60 k Brassica Infinium SNP array. We identified seven loci for PH, four for BIH, and five for BN. Subsequently, by determining linkage disequilibrium (LD) decay associated with 38 significant SNPs, we gained 31, 15, and 17 candidate genes for these traits, respectively. We also showed that PH is significantly correlated with BIH, while no other correlation was revealed. Notably, a GA signaling gene (BnRGA) and a flowering gene (BnFT) located on chromosome A02 were identified as the most likely candidate genes associated with PH regulation. Furthermore, a meristem initiation gene (BnLOF2) and a NAC domain transcriptional factor (BnCUC3) that may be associated with BN were identified on the chromosome A07. This study reveals novel insight into the genetic control of plant architecture and may facilitate marker-based breeding for rapeseed.
TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik, 2003
Recently-introduced inter-specific Musa hybrids, bred for improved yield and resistance to diseas... more Recently-introduced inter-specific Musa hybrids, bred for improved yield and resistance to diseases, have been found to be widely infected with banana streak virus (BSV), the causal agent of banana streak disease (BSD). One hypothesis suggests: (1) that BSD occurrence in these inter-specific hybrids results from activation of BSV-Ol endogenous pararetrovirus sequences (EPRV) integrated into the Musa genome rather than from external sources of infection, and (2) that the process of genetic hybridisation may be one factor involved in triggering episomal expression of the BSV integrants. In order to test this hypothesis we carried out a genetic analysis of BSD incidence in a F1 triploid ( Musa AAB) population produced by inter-specific hybridisation between virus and disease-free diploid Musa balbisiana (BB) and tetraploid Musa acuminata (AAAA) parents. Half of the F1 progeny of this cross expressed BSV particles. Using PCR amplification to determine the presence or absence of BSV-Ol E...
International Symposium on Recent Advances in Banana Crop Protection for Sustainable Production and Improved Livelihoods, 2009
Banana streak viruses (BSVs) are double-stranded DNA pararetroviruses causing banana streak disea... more Banana streak viruses (BSVs) are double-stranded DNA pararetroviruses causing banana streak disease. Recently, numerous outbreaks of the disease occurred in many banana-producing areas in interspecific hybrids (#Musa acuminata# × #Musa balbisiana#) originating from virus-free parents. These infections correlated with the presence of endogenous banana streak viruses (eBSVs), viral DNA sequences integrated in the #M. balbisiana# genome only. Although integration is not needed for the viral replication cycle, some viral integrants are infectious under stress conditions by reconstituting a replication-competent genome after possible homologous recombination events. Even though the wild #M. balbisiana# Pisang Klutuk Wulung (PKW) harbours infectious eBSVs, it is resistant to BSVs. We characterised the genetic and genomic endogenous viral organisation of three BSV species in PKW in order to determine the species responsible for the viral expression in the interspecific F1 progeny. (Resume d'auteur)
La maladie de la mosaique en tirets des bananiers BSD frappe aujourd'hui la majorite des zone... more La maladie de la mosaique en tirets des bananiers BSD frappe aujourd'hui la majorite des zones productrices de bananes. Le virus responsable BSV est un badnavirus. Ces dernieres annees, la veritable contrainte a reside dans l'association etroite de l'apparition de la maladie avec l'obtention et la diffusion de nouvelles varietes de bananiers. Des cultivars sains multiplies par CIV ou des geniteurs utilises lors de croisements genetiques restituent soit des vitroplants soit des hybrides contamines. Un pourcentage non explique de plants BSD voisin de 50% a ete observe dans les descendances d'hybridation de geniteurs sains. Ceci a ete interprete comme le resultat d'une segregation a caractere mendelien de l'expression de la maladie. Au moins 4 souches BSV (Mys, Wu, Gf et Im) existent sous diverses formes : libres comme particule episomale infectieuse, ou integrees sous forme de sequences partielles ou totales dans le genome B. Le modele actuel BSV-Wu suggere une double recombinaison conduisant a l'excision des deux fragments internes et a la circularisation aboutissant a la forme superenroulee transcriptionnellement active. L'analyse du motif activable n'a pas montre d'homologie avec les retrotransposons pour leurs elements majeurs. Afin d'identifier et d'analyser les mecanismes moleculaires induisant la multiplication de la souche BSV-Wu au cours de l'amelioration conventionnelle, nous avons tente de definir un marqueur genetique viral utilisable par les geneticiens pour identifier les bananiers sains. Des marqueurs moleculaires lies a la presence ou a l'absence de virus episomal ont ete recherches par Bulk segregant analysis et par AFLP dans la F1 de deux croisements interspecifiques (IDN110 4A x PKW 2B). 11 marqueurs polymorphes relies au parent B ont ete isoles : 7 segregent avec le facteur declenchant et sont correles a l'expression du virus episomal, 4 avec le phenotype 'absence de virions'. Leur analyse a permis d'etablir une carte genetique du locus implique dans l'expression du virus. Le marqueur de la maladie le plus proche est a OcM du facteur declenchant. L'analyse de sa sequence revele une homologie de 86% avec le retrotransposon 'Monkey' identifie chez #Musa Acuminata#. Ce pathosysteme constitue du fait de la presence simultane de sequences integrees et d'un systeme de replication du virus, un candidat ideal pour une hypothese forte de gene silencing. (Resume d'auteur)
Inter-specific #Musa# hybrids have been found to be infected with several Banana streak pararetro... more Inter-specific #Musa# hybrids have been found to be infected with several Banana streak pararetrovirus strains (BSV-Obino l'Ewai (BSV-Ol), BSV-Imove (BSV-Im) and BSV-Gold Finger (BSV-GF) strains) resulting from activation of BSV endogenous pararetrovirus sequences (EPRVs) integrated into the #Musa# genome rather than from external sources of infection. The process of genetic hybridisation may be responsible in triggering episomal expression of the BSV integrants. In order to test this hypothesis we carried out a genetic analysis of BSD incidence in a F1 triploid (AAB) population produced by hybridisation between virus- and disease-free #M. balbisiana# (BB) and #M. acuminata# (AAAA) parents. Molecular AFLP markers were identified in the #M. balbisiana# genome only. Analysis of the segregation of these markers allowed the construction of a genetic map containing the locus associated with BSV infection called BSV Express locus (BEL). The BSV-Ol and BSV-Im strains appeared in almost all diseased hybrids while the BSV-GF strain appeared only in about half of these hybrids. Genetic analysis resulting from AFLP results showed that BSV-Ol and BSV-Im EPRVs' expression depends on the same genetic factor, the BEL locus. Although the BSV-GF is not genetically linked to the BEL locus, its appearance and the activation of corresponding EPRV(s) seem to be also subordinated to the BEL locus. So, the discovery of several BSV EPRVs linked to BEL locus implicates that BEL differs in nature from BSV EPRVs. (Resume d'auteur)
Inter-specific #Musa# hybrids have been found to be infected with Banana streak pararetrovirus Ob... more Inter-specific #Musa# hybrids have been found to be infected with Banana streak pararetrovirus Obino I'Ewai strain (BSV-Ol) responsible of Banana Streak Disease (BSD). One hypothesis suggest (i) that BSD occurrence in these hybrids results from activation of BSV-Ol endogenous pararetrovirus sequences (EPRVs) integrated into the #Musa# genome rather than from external sources of infection and (ii) that the process of genetic hybridisation may be one factor involved in triggering episomal expression of the BSV integrants. In order to test this hypothesis we carried out a genetic analysis of BSD incidence in a F1 triploid (AAB) population produced by hybridisation between virus- and disease-free #M. balbisiana# (BB) and #M. acuminata# (AAAA) parents. Half of the F1 progeny expressed BSV particles. Ten AFLP markers co-segregating with the absence and/or presence of BSV infection were identified in the #M. balbisiana# genome only. Analysis of the segregation of these markers allowed the construction of a genetic map containing the focus associated with BSV infection called BSV Express Locus (BEL). A genetic mechanism is involved in BSV appearance, conferring the role of carrier to the #M. balbisiana# parent. Two previously unidentified BSV strains in addition to BSV-Ol, have been furthermore detected in these diseased hybrids: BSV-Imove (BSV-Im) and BSV-Gold Finger (BSV-GF) strains. The BSV-Ol and BSV-Im strains appeared in almost all diseased hybrids while the BSV-GF strain appeared only in about half of these hybrids. The close relationships between the presence of these two new BSV strains and the presence of corresponding EPRVs in the #M. balbisiana# parent genome shows that the #M. balbisiana# genome contains at least two other pathogenic BSV EPRVs: BSV-Im and BSV-GF EPRVs. Genetic analysis resulting from AFLP results showed that BSV-0l and BSV-Im EPRVs' expression depends on the same genetic factor, the BEL locus. Although the BSV-GF is not genetically linked to the BEL locus, the BSV-GF strain appearance and the activation of corresponding EPRV(s) seem to be also subordinated to the BEL locus. So, the discovery of new BSV EPRVs linked to BEL locus implicates that BEL differs in nature from BSV EPRVs. Our interest is now the understanding of (i) the mechanism of activation of these strains resulting in BSV expression from EPRVs and (ii) the apparent resistance of the #M. balbisiana# parent against BSV expression and external infection. (Resume d'auteur)
Ces dernieres annees des hybrides interspecifiques bananiers ont developpe la maladie de la mosai... more Ces dernieres annees des hybrides interspecifiques bananiers ont developpe la maladie de la mosaique en tirets, sans possibilite de contamination externe par le Banana streak badnavirus-BSV responsable. L'explication proposee fait l'hypothese que les virions observes proviennent de sequences virales endogenes - EPRVs BSV, presentes dans le genome bananier. L'objectif de notre etude a ete de tenter de trouver une explication a l'expression de la maladie au cours de l'hybridation conventionnelle pour deux croisements #Musa# interspecifiques - PKW (BB) x IDN 110 4x (AAAA) et P. batu (BB) x P. pipit 4x (AAAA). Nous avons tout d'abord montre l'existence d'une segregation a caractere mendelien de la maladie sur les descendances F1 et revele la presence du BSV dans 50% des plants. L'etude de l'EPRV BSV souche Obino l'Ewai (BSV-O1) a montre sa presence a l'etat homozygote dans le genome #M. balbisiana# uniquement. Une carte genetique du locus responsable de l'expression de la maladie -BEL (BSV expressed locus) a ete proposee sur la base de l'analyse de 10 marqueurs AFLP de l'expression ou non de la maladie, tous localises chez les parents #M. balbisiana#. Les analyses genetiques revelent chez le parent #M. balbisiana#, la presence d'un systeme allelique monogenique lui conferant le role de porteur sain. La regulation des EPRVs a ete abordee au travers de l'analyse d'apparition des trois souches BSV presentes dans les hybrides malades: la souche BSV-O1 dans 98% des cas, BSV-Im dans 88% et BSVGF uniquement dans la moitie d'entre eux. Les EPRVs correspondantes sont dans les genomes #M. balbisiana# et dans la population hybride, suggerant leur caractere pathogene. L'analyse genetique a montre que les souches BSV-O1 et BSV-Im sont genetiquement liees et dependent du facteur genetique BEL. La souche BSV-GF apparait non liee genetiquement au locus BEL mais reste sous son controle. L'existence d'au moins trois EPRVs pathogenes dependantes du facteur BEL implique que la nature de ce dernier est differente de sequences virales. Plus generalement des elements utiles a la comprehension de ce mecanisme de regulation des EPRVs ont ete recherches en explorant le comportement "sain" du parent femelle #M. balbisiana#. Ce dernier presente une resistance tant a l'expression des EPRVs qu'a celle des souches BSV lors d'inoculations exterieures. (Texte integral)
Journal of Virology, 2008
Sequencing of plant nuclear genomes reveals the widespread presence of integrated viral sequences... more Sequencing of plant nuclear genomes reveals the widespread presence of integrated viral sequences known as endogenous pararetroviruses (EPRVs). Banana is one of the three plant species known to harbor infectious EPRVs. Musa balbisiana carries integrated copies of Banana streak virus (BSV), which are infectious by releasing virions in interspecific hybrids. Here, we analyze the organization of the EPRV of BSV Goldfinger (BSGfV) present in the wild diploid M. balbisiana cv. Pisang Klutuk Wulung (PKW) revealed by the study of Musa bacterial artificial chromosome resources and interspecific genetic cross. cv. PKW contains two similar EPRVs of BSGfV. Genotyping of these integrants and studies of their segregation pattern show an allelic insertion. Despite the fact that integrated BSGfV has undergone extensive rearrangement, both EPRVs contain the full-length viral genome. The high degree of sequence conservation between the integrated and episomal form of the virus indicates a recent int...
Hereditas, 2004
The genetic diversity and structure in 17 wild populations (249 individuals) of Phytolacca dodeca... more The genetic diversity and structure in 17 wild populations (249 individuals) of Phytolacca dodecandra (endod) sampled along altitudinal gradients of 1600-3000 meters above sea level (m.a.s.l.) in Ethiopia was studied using random amplified polymorphic DNA (RAPD). A total of 70 polymorphic loci (P) scored from 12 RAPD primers were used to calculate different diversity indices within and between populations, habitats, geographical regions, climatic zones and altitude groups. The number of polymorphic loci and overall Shannon information measure (H) in the populations varied from 30 to 55 and from 0.228 to 0.418, respectively. In general, differences in population variability were found significantly correlated to effective population size. Both P and H were significantly higher in an undisturbed than in a disturbed habitat, and in the lowland and central-highland than in the highland altitude group. However, for both parameters the differences were not statistically significant between regions and climatic zones. Genetic distance between populations varied from 0.301 to 0.628. Cluster analysis performed using the genetic distance matrix revealed a clear separation of the highland populations (2501-3000 m.a.s.l.) from those of the lowland/central-highlands (1600-2500 m.a.s.l.) irrespective of their geographical regions and climatic zones. Analysis of molecular variance (AMOVA) indicated that differences in habitat, geographical regions and climatic zones explained 4.6%, 2.5% and 4.6%, respectively. But none of these differences were significant. Altitude explained 17.2% of the total variance and was highly significant. The data, therefore, clearly indicated the association of genetic structure in endod with altitude. The proportion of RAPD variation found among populations (21.2-35.0%) was somewhat intermediate between values reported for selfing and outcrossing species. The fixation index (FST) values (0.350 to 0.384) indicated very high genetic differentiation among populations.
Genome, 2004
The first bacterial artificial chromosome (BAC) library of the banana species Musa balbisiana ... more The first bacterial artificial chromosome (BAC) library of the banana species Musa balbisiana 'Pisang Klutuk Wulung' (PKW BAC library) was constructed and characterized. One improved and one novel protocol for nuclei isolation were employed to overcome problems caused by high levels of polyphenols and polysaccharides present in leaf tissues. The use of flow cytometry to purify cell nuclei eliminated contamination with secondary metabolites and plastid DNA. Furthermore, the usefulness of the inducible pCC1BAC vector to obtain a higher amount of BAC DNA was demonstrated. The PKW BAC library represents nine haploid genome equivalents of M. balbisiana and its mean insert size is 135 kb. It consists of two sublibraries, of which the first one (SN sublibrary with 24 960 clones) was prepared according to an improved standard nuclei isolation protocol, whereas the second (FN sublibrary with 11 904 clones) was obtained from flow-sorted nuclei. Screening with 12 RFLP probes, which wer...
Virologie, 2003
... Auteur(s) : M.-L. Iskra-Caruana 1 , F. Lheureux 1 , P.-Y. Teycheney 2. ... Elle permet la col... more ... Auteur(s) : M.-L. Iskra-Caruana 1 , F. Lheureux 1 , P.-Y. Teycheney 2. ... Elle permet la colonisation de nouvelles plantes et, de fait, nécessite un intermédiaire appelé vecteur dont la nature est très variée : arthropodes le plus souvent, nématodes, champignons ou même parfois ...
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Papers by Fabrice Lheureux