WorldCat Identities

Frendo, Pierre

Overview
Works: 20 works in 24 publications in 2 languages and 163 library holdings
Roles: Editor, Other, Opponent, Thesis advisor, Author
Publication Timeline
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Most widely held works by Pierre Frendo
Regulation of nitrogen-fixing symbioses in legumes( )

3 editions published in 2020 in English and held by 140 WorldCat member libraries worldwide

The Nitrogen-Fixing Legume-Rhizobium Symbiosis, Volume 94, the latest release in the Advances in Botanical Research series, highlights new advances in the field, with this new volume presenting interesting chapters on The diversity of legume-rhizobium symbioses, Parasponia; an evolutionary outlier of rhizobium symbiosis, Rhizobium diversity in the light of evolution, Genomes of rhizobia, Gene regulation by extracytoplasmic function (ECF) sigma factors in alpha-rhizobia, Early symbiotic signaling between Plant and Bacteria, Rhizobia infection, a journey to the inside of plant cells, Differentiation of symbiotic nodule cells and their rhizobium endosymbionts, Nodule Organogenesis, Nitrogen Fixation by the Legume-Rhizobium Symbiosis, and much more. --
LES PROTEINES DE STRESS CHEZ LE MAIS : CLONAGE DES ADNC DE PROTEINES INDUITES PAR DIVERS STRESS ABIOTIQUES. ETUDE DES SEQUENCES ET DE L'INDUCTION D'UNE PROTEINE THAUMATIN-LIKE ET D'UNE GLUCANASE by Pierre Frendo( Book )

2 editions published in 1993 in French and held by 2 WorldCat member libraries worldwide

LE CRIBLAGE DIFFERENTIEL D'UNE BANQUE D'ADNC CONSTRUITE AVEC DES ARNM DE FEUILLES DE MAIS TRAITEES AU CHLORURE MERCURIQUE NOUS A PERMIS D'ISOLER LES ADNC DE 11 PROTEINES DONT LA TRANSCRIPTION EST INDUITE OU AMPLIFIEE APRES UN STRESS PAR LE CHLORURE MERCURIQUE. LA CYCLOPHILINE (CHEM7), LE TRANSPORTEUR DE PHOSPHATE (CHEM10), LA PROTEINE DE CANAL MEMBRANAIRE (CHEM8), LA PROTEINE DE CHOC THERMIQUE (CHEM3), L'UBIQUITINE (CHEM6) ET LES PROTEINES RICHES EN GLYCINE (CHEM1, 2, 11) PEUVENT CONTRIBUER A LA SURVIE DE LA CELLULE EN JOUANT UN ROLE AU NIVEAU CELLULAIRE. LES CHITINASES (CHEM5), LES GLUCANASES (CHEM9) ET LES PROTEINES THAUMATIN-LIKE (TL) (CHEM4) SONT PLUS SPECIFIQUES DE LA DEFENSE DE LA PLANTE. LA SEQUENCE PROTEIQUE DE LA PROTEINE TL PRESENTE 70% D'IDENTITE AVEC LES PROTEINES TL DE BLE ET D'ORGE. CES PROTEINES TL DIFFERENT DES AUTRES PROTEINES TL PAR LA PRESENCE D'UNE DELETION IMPORTANTE. ELLES SEMBLENT FORMER DANS L'ECART ACTUEL DE NOS CONNAISSANCES UNE NOUVELLE FAMILLE DE PROTEINES TL SPECIFIQUE DES CEREALES. LA TRANSCRIPTION DES GENES CODANT PAR CHEM4 EST FORTEMENT INDUITE PAR LE CHLORURE MERCURIQUE ET L'IRRADIATION PAR LA LUMIERE ULTRAVIOLETTE. L'ADNC DE LA PRM6B A EGALEMENT ETE ISOLE A L'AIDE D'UN OLIGONUCLEOTIDE DE SYNTHESE. LA TRANSCRIPTION DES GENES CODANT POUR LA PRM6B EST FORTEMENT INDUITE PAR LE TRAITEMENT AU CHLORURE MERCURIQUE ET PAR L'IRRADIATION A LA LUMIERE ULTRAVIOLETTE. L'EXPOSITION DES PLANTES TRAITEES A 32C INHIBE LA TRANSCRIPTION DES GENES NORMALEMENT INDUITS PAR LE CHLORURE MERCURIQUE A TEMPERATURE AMBIANTE. UN TRAITEMENT CHIMIQUE A L'ACIDE SALICYLIQUE INDUIT LA TRANSCRIPTION DES GENES DE CHEM3, DE CHEM4, DE CHEM5 ET DE CHEM9 MAIS PAS CELLE DES GENES DE CHEM1. UN TRAITEMENT CHIMIQUE A L'ETHEPHON INDUIT LA TRANSCRIPTION DES GENES DE CHEM1, DE CHEM3 ET DE CHEM9 MAIS PAS CELLES DES GENES CHEM4 ET DE CHEM5
Glutathione synthesis is regulated by nitric oxide in Medicago truncatula roots by Gilles Innocenti( )

1 edition published in 2006 in English and held by 2 WorldCat member libraries worldwide

Étude de l'importance de composés antioxydants lors d'interactions biotrophes pathogènes ou symbiotiques by Fabien Baldacci-Cresp( Book )

2 editions published in 2011 in French and held by 2 WorldCat member libraries worldwide

Plants are subject to changes in their biotic environment to which they must adapt. This biotic environment of the plant includes both deleterious-pathogenic and beneficial-symbiotic microorganisms. The redox state is not only a major component of cell functioning throughout the living kingdom but also a major component of plant adaptation to their environment. Many components of the redox state may be involved in his adaption to their environment. Many components of the redox state may be involved in this adaptation. Glutathione (GSH) and thioredoxin system are two of the key players. During this PhD Work, the involvement of GSH in the interaction between the legumes, Medicago truncatula, and the root-knot nematode, Meloidogyne incognita, was studied. The analysis of developmental phenotypes, metabolite content and gene expression under glutathione deficiency showed the importance of GSH in the pathogen development and the specific regulation of the gall carbon metabolism. In parallel, the importance of two thioredoxins strongly induced during the nitrogen fixing symbiosis between M. truncatula and the soil bacterium S. meliloti was studied. Gene silencing experiments showed that thioredoxin deficiency affects the symbiotic efficiency. In addition, the study of their localization in the nodule infected cells showed that a transfer of these thioredoxins occurs from the plant to the bacterial partner
Plant-Rhizobium symbiosis, seed nutraceuticals, and waste quality for energy production of Vicia faba L. as affected by crop management by Carmine Amalfitano( )

1 edition published in 2018 in English and held by 2 WorldCat member libraries worldwide

Le glutathion chez Medicago truncatula : étude de la régulation de sa synthèse et identification de gènes cibles lors de la symbiose avec Sinorhizobium meliloti by Gilles Innocenti( Book )

1 edition published in 2008 in French and held by 1 WorldCat member library worldwide

Symbiosis between Medicago truncatula and Sinorhizobium meliloti leads to the formation of root nodules able to reduce atmospheric nitrogen. Glutathione (GSH) and its homologue homoglutathione (hGSH) are two antioxidants involved in many essential plant functions. During this PhD work, regulation of GSH and hGSH biosynthesis genes by nitric oxide (NO) was studied and a transcriptomic analysis was carried out in order to identify (h)GSH target genes during the nodulation process. Two chemical NO donors, are able to increase the amount of [gamma]-glutamylcysteine synthetase and glutathione synthetase transcripts, but not homoglutathione synthetase transcripts, suggesting the two thiols could have different roles. GSH accumulation correlated with gene expression, showing NO induces GSH synthesis in Medicago truncatula roots. NO, which has been detected in nitrogen fixative nodules, could therefore be involved in antioxidant defence during symbiosis by the activation of GSH synthesis. Transcriptomic analysis by cDNA-AFLP allowed us to identify 181 genes regulated by (h)GSH depletion during the nodulation process ; amongst them, genes related to meristem development, signal transduction and plant defence. Expression profile analysis of genes induced by salicylic acid suggest defence mechanisms linked to this hormone are impaired in (h)GSH-depleted plants. The results obtained during this work bring us new elements on (h)GSH implication in plant defence regulation and open the way to new studies on the various roles of this molecule in nodulation mechanisms, and more generally in plant-microorganism interactions
Diversité génétique du nématode vecteur Xiphinema index sur vigne et application pour optimiser la stratégie de résistance by Van Chung Nguyen( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

The ban of most nematicides renders urgent control alternatives against plant-parasitic nematodes and breeding for resistant plant varieties is promising. In vineyards, the nematode Xiphinema index has a high economical impact by transmitting Grapevine fanleaf virus (GFLV), the main virus of 'Court-noué' disease and the first grapevine viral disease worldwide. Resistant rootstocks are being selected in grapevine, using Muscadinia rotundifolia (muscadine) as a resistance source to the vector, in order to arrest or delay GFLV transmission. In this crop, a previous study had shown that this meiotic parthenogenetic nematode is able to reproduce sexually (rarely) in the field. A preliminary phylogenetic work had allowed to reveal the predominant diversity groups and to select representative populations for the creation of single-female lines. Resistance durability is a real challenge that must consider the key information of the nematode diversity. In this context, the PhD project first completed and deepened our phylogeographical approach using an extended geographic coverage of the worldwide nematode distribution. Our results allow proposing strong hypotheses to locate the native area of X. index in the Middle-East and trace its dissemination routes from the Antiquity. They also highlight the close link since this epoch between dissemination of the nematode and domesticated grapevine by man. The second part of the PhD project has then evaluated the durability of muscadine-derived rootstock material in greenhouse (non viruliferous nematodes on plants aged 3 to 6 years) and field (viruliferous nematodes on plants aged 16 years) conditions. In the greenhouse, F1 and BC1 resistant accessions, previously obtained from both in vitro and hardwood-cutting propagation, were inoculated with 4 mixed representative X. index lines, traceable each with microsatellite markers. We showed that nematodes from plants obtained from in vitro progressively overcame the resistance while the material obtained from cuttings displayed a durable resistance. Nematode progressive multiplication in resistant accessions obtained only from in vitro removes a priori the hypothesis of a nematode genetic adaptation and appears linked to a different architecture of the root system in this propagation type. This type may have induced discrete but durable physiological changes in apical root tissues from where nematodes feed. Nematode microsatellite genotyping allowed detecting a low but increasing rate of hybrid individuals from 4 to 6 years, which confirms data from the vineyard. As the hybrid occurrence appears independent from the propagation type and the resistance status of the plant, our data discard hybridization as the mode of adaptation of the nematode underlying resistance breakdown from in vitro plants. In field conditions, after 16 years, nematodes were almost undetectable on the resistant BC1 accession, also almost unaffected by the viral attacks, while higher numbers were detected on a susceptible control accession, whose plants were by contrast in high majority dead or poorly vigorous. Taken all together, our results show that the muscadine-derived resistance strategy appears durable. This strategy focused on vector control will significantly contribute to reduce the impact of GFLV transmitted by X. index
L'effecteur Avh195 de Phytophthora parasitica : antagoniste de l'autophagie chez l'hôte et promoteur du processus infectieux by Serena Testi( )

1 edition published in 2018 in English and held by 1 WorldCat member library worldwide

The plant pathogen Phytophthora parasitica is an oomycete with devastating impact on both agriculture and natural ecosystems. As a hemi-biotrophic organism it infects the roots of plants first establishing an intimate contact with host cells (biotrophy) before killing them (necrotrophy) and completing its infection cycle. To control these processes, oomycetes secrete effector proteins, which are internalized in plant cells by a translocation motif (called RxLR-EER) to manipulate the physiology and the immune responses of the host. Studies of the molecular exchanges between Phytophthora parasitica and the plant that were conducted by the hosting laboratory led to the identification of an RxLR effector, designed to as Avh195. The amino acid sequence of the effector is characterized by the presence of five AIMs (ATG8 interacting motifs), that indicate a potential interaction with the autophagic core protein, ATG8. Avh195 colocalizes with the membrane-bound fraction of ATG8, and a yeast two-hybrid system, which allows to determine interactions between membrane proteins, confirmed a non-selective interaction between Avh195 and several ATG8 isoforms. The characterization of Avh195-dependent autophagy perturbation was carried out in the unicellular alga Chlamydomonas reinhardtii after generation of transgenic lines overexpressing the effector. Analyses by flow cytometry revealed that Avh195 does not modify the physiology and fitness of the alga, both under normal growth conditions and during rapamycin-induced autophagy. Transmission electron microscopy of cells revealed that the effector provokes a delay in the autophagic flux, manifested as a reduced coalescence and clearance of autophagic vacuoles and a strong accumulation of starch in chloroplasts. However, this phenotype was transient and only slightly related to modifications in the transcriptional regulation of the autophagic machinery. The analysis of effector function in planta showed that Avh195 delays the development of hypersensitive cell death, which is triggered by an oomycete elicitor. This cell death-delaying activity is dependent on three out of five AIMs, further consolidating the importance of the Avh195-ATG8 interaction for the function of the effector. The stable overexpression of Avh195 in A. thaliana allowed to determine that the effector does not impair plant defense responses, but overall promotes the development of the pathogen, accelerating the switch from biotrophy to necrotrophy during infection. To our knowledge, the work presented in this thesis represents the first evidence for an oomycete effector to possess a transitory activity, which targets in a non-selective manner the protein ATG8 in different organisms from the green lineage to slow down autophagic flux, thus promoting the hemibiotrophic life style of a pathogen
Le locus de résistance Ma des Prunus vis-à-vis des nématodes à galles : Originalité structurale et évolution dans la famille des NBS-LRRs chez les plantes by Cyril Van Ghelder( )

1 edition published in 2019 in French and held by 1 WorldCat member library worldwide

Root-knot nematodes (RKNs), Meloidogyne spp., are extremely polyphagous pests that severely challenge plants worldwide and especially perennials. The specific genetic resistance of plants mainly relies on NBS-LRR receptor genes (or NLRs grouping TNL, CNL and RNL subfamilies) that are pivotal factors for control of pests and pathogens. In Prunus spp., the Ma plum TNL gene confers resistance to all RKNs tested, whereas the RMja almond gene displays a more restricted spectrum of resistance (R). Moreover, the Ma predicted protein shows a peculiar TNL structure due to a C-terminal region made of five repeated domains, designated post-LRR domains (PLs). In this context, this thesis work has characterised the originality and the distribution of this uncommon structure among diverse plant proteomes and has revealed the genetic relationship between the Ma and RMja genes.We first studied the frequency, distribution and structural characteristics of TNL genes and PL domains within the peach genome, the reference genome for Rosaceae. The finding of PL domains, which have been identified in two thirds of the 195 TNLs, allowed us to define specific motifs that improve the detection of this poorly known domain in Angiosperms. We found that the PL domain is specific of TNLs and is present in Angiosperm genomes in a proportion similar to the one established for peach. Besides, TNLs displaying multiple PL domains are rare in plants. The five-PL domain pattern is probably unique to Ma and its orthologues and was probably inherited from their common ancestor in the order Rosales. We then investigated the NBS-LRR repertoire of the conifers (Gymnosperms), an ancient taxonomic group, for which the data related to this gene family are unclear. By analysing seven reference transcriptomes, we highlighted a large and diverse NBS-LRR arsenal in conifers but, surprisingly, no PL signatures have been detected. The examination of ancient plant proteomes revealed that only Ginkgo biloba displayed a few PL signatures. Our results suggest that a partial acquisition of the PL domain occurred early in seed plants and was followed by an adaptive expansion in Angiosperms. Additionally, we showed that conifers and Rosaceae have numerous RNLs and TNLs. By enlarging our study to other land plant genomes, we uncovered an average ratio of 1:10 between RNLs and TNLs numbers.We finally carried out a high-resolution mapping of the RMja gene in almond. Using a BAC library, RMja was localised into the Ma resistance cluster and the Ma orthologue is by far the best candidate. The sequence comparison between three orthologous regions of the Ma locus, i.e. plum (complete R spectrum), almond (incomplete R spectrum) and peach (null R spectrum) highlighted a unique conserved structure of the Ma orthologues. Our results suggest that the polymorphism contained in the PL-domain repeats might underlie differential resistance interactions with RKNs and an original immune mechanism in woody perennials. In these immune processes for recognition or signalling, other components such as RNLs might be involved. This work paves the way for future comparative and functional approaches aiming to unravel the molecular determinants involved in the resistance to RKNs
Analyse fonctionnelle des effecteurs nucléaires du parasitisme des nématodes à galle Meloidogyne incognita et caractérisation de leurs cibles végétales by Nhat My Truong( )

1 edition published in 2016 in French and held by 1 WorldCat member library worldwide

The root-knot nematode Meloidogyne incognita is among the most devastating plant pathogens
Etude de suppresseurs de la glutarédoxine GRXS17 dans la croissance racinaire et la thermotolérance by José Abraham Trujillo Hernández( )

1 edition published in 2019 in English and held by 1 WorldCat member library worldwide

Les auxines sont des composants clés essentiels pour le contrôle du développement des racines et la réponse aux contraintes environnementales en raison de leur rôle central dans la division, l'élongation et la différenciation cellulaires. L'auxine endogène, acide indole-3-butyrique (IBA), bien que moins abondante et moins connue que l'acide indole-3-acétique (IAA), joue un rôle important dans le développement racinaire, en particulier lors de la formation des racines latérales et de l'élongation des poils absorbants. Il est généralement admis que les fonctions de l'IBA dépendent entièrement de la conversion peroxysomale de l'IBA en IAA. Bien que nos connaissances concernant les enzymes impliquées dans cette conversion soient très avancées, nous en savons peu sur les mode de régulation de ces fonctions. Au cours de ma thèse, j'ai démontré que les fonctions de l'IBA lors de l'induction des racines latérales et de l'élongation des poils absorbants dépendent du glutathion, un petit tripeptide rédox qui constitue l'une des molécules les plus importantes impliquées dans les réponses des plantes au stress oxydatif. De plus, j'ai démontré que le lien entre le glutathion et l'auxine IBA est essentiel pour les réponses à l'auxine dans la zone de transition de la racine primaire. Ce contrôle des fonctions de l'IBA par le glutathion pourrait être déterminant dans des conditions de stress abiotiques telles que la carence en phosphore.Une des fonctions du glutathion étant de réduire des réductases de fonctions thiols, les glutaredoxines (GRX), nous avons recherché si certaines GRX sont impliquées dans le développement racinaire. Nous avons constaté que ROXY19 et GRXS17 sont essentiels à la croissance des racines primaires et que ces deux GRX sont également impliqués, mais dans des rôles différents, lors du développement des racines latérales. Un crible suppresseur des phénotypes racinaires du mutant grxs17 avait été mis en place dans le laboratoire. J'ai utilisé des approches bio-informatiques pour isoler les mutations causales après reséquençage du génome de candidats capables de restaurer la croissance des racines primaires et / ou le développement normal des primordia des racines latérales. Malheureusement, cette approche ne nous a pas encore permis d'isoler de nouveaux acteurs. Cependant, elle jette les bases d'un futur grand progrès dans la compréhension de la manière dont GRXS17 contrôle le système racinaire.En conclusion, les résultats de ma thèse soulignent l'importance du glutathion et des glutarédoxines dans le contrôle de la plasticité du système racinaire et lors de conditions de stress abiotiques, notamment via la modulation de la voie auxinique IBA
Étude de l'interaction entre Phytophthora parasitica et le microbiote rhizosphérique à la surface de la plante hôte Solanum lycopersicum by Marie Larousse( )

1 edition published in 2016 in French and held by 1 WorldCat member library worldwide

The interactions between a pathogen and the host surface resident microbiota are critical to disease outbreak. These interactions shape the distribution, the density and the genetic diversity of inoculum. However for most plant pathogens how each of these interactions acts on disease as a single one or as a member of a functional network remains to be specified. This issue is addressed here through the analysis of two types of interactions involving the polyphagous oomycete P.parasitica : (i) the intraspecific interaction that leads to monospecific biofilm formation by P. parasitica zoospores on plant surface; (ii) the interspecific interactions that occur between P. parasitica biofilm and the prokaryotic microbiota of Solanum lycopersicum rhizosphere. The biology of monospecific biofilm is investigated through the characterization of MUCL, a new oomycete-specific Mucin-like Protein family. Gene profiling, biochemical and immunohistological analyses define the extent of this family and lead to identify three members, PPMUCL1/2/3, as residing in P. parasitica biofilm. The Phytophthora parasitica-Microbiota interaction is explored using first a metagenomic approach. Two microbial metagenomes derived from a soil of a tomato greenhouse is defined and compared after 16S RNA gene sequencing: M1 which corresponds to the sub-rhizospheric microbiota able to colonize the roots of axenic tomato seedlings; M2, the sub-microbiota able to colonize the tomato seedling roots previously coated with P. parasitica monospecific biofilm. A representative collection of microorganisms from M2 were also obtained through in vitro selection on a medium prepared from P. parasitica extract
Regulation of nitrogen-fixing symbioses in legumes : from functions to possible applications( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Identification de nouveaux régulateurs de la sénescence nodositaire chez Medicago truncatula by Theophile Kazmierczak( )

1 edition published in 2016 in French and held by 1 WorldCat member library worldwide

La sénescence constitue la dernière étape du cycle de vie de certains organes des plantes. Elle permet leur dégradation tout en réallouant les constituants des tissus sénescents vers d'autres organes. Dans le contexte de la nodulation symbiotique fixatrice d'azote entre certaines plantes légumineuses et des bactéries rhizobia, un processus de sénescence a été décrit. Cependant, les connaissances sur les mécanismes de régulation de la sénescence des nodosités symbiotiques sont limitées. Au sein du laboratoire, le facteur de transcription MtNAC969 a été identifié comme un régulateur de la sénescence des nodosités. L'objectif de cette thèse est d'identifier et de caractériser de nouveaux régulateurs de la sénescence de l'organe symbiotique. Nous avons développé : (i) une approche visant à identifier des facteurs de transcription corégulés avec MtNAC969 ou avec une cystéine protéase MtCP6 utilisée comme marqueur de la sénescence des nodosités ; et (ii), une approche avec "à priori" se focalisant sur la fonction des différentes voies de signalisation des cytokinines. Cette thèse a permis d'identifier deux facteurs de transcription, MtbHLH107 et MtNAC009 et de décrypter le rôle des cytokinines dans la sénescence des nodosités. Cette thèse a permis d'identifier d'une part, deux nouveaux gènes potentiellement régulateurs de la sénescence nodositaire, MtbHLH107 et MtNAC009; et d'autre partde décrypter le rôle des cytokinines dans la sénescence de cet organe symbiotique
Analyse fonctionnelle de cibles végétales d'effecteurs du parasitisme du nématode Meloidogyne incognita impliquées dans l'ontogénèse des cellules géantes by Joffrey Mejias( )

1 edition published in 2020 in French and held by 1 WorldCat member library worldwide

Plant parasitic nematodes of the genus Meloidogyne, or root-knot nematodes, are a major phytosanitary problem worldwide. These obligate plant parasites have developed original and complex parasitism strategies. By injecting proteins called "effectors" into the host plant, they induce cell reprogramming and the transformation of root cells into enlarged and polynucleated feeding cells, named "giant cells". However, little is known about the determinism of these newly formed structures in plants. During my thesis, I focused on two proteins secreted by the root-knot nematode M. incognita: the effector 18 encoded by a pioneer gene (MiEFF18) and a protein disulfide isomerase (MiPDI). We have identified the plant protein targeted by the effectors using a yeast two hybrid screen approach and we have studied their roles in the compatible interaction and the formation of giant cells. Immunolocalisation experiments have shown that the protein MiEFF18 is produced in the salivary glands, accumulates in secretory granules indicating that it could be secreted in planta via the stylet. The use of translational fusions between MiEFF18 and GFP has shown that this effector accumulates in the nucleus and nucleolus of plant cells. The SmD1 proteins have been identified as MiEFF18 targets in tomato, Arabidopsis and in N. benthamiana. These SmD1 proteins are conserved and essential components of the spliceosome and the eukaryotic messenger RNA splicing machinery. The sequencing of the transcripts (RNAseq) of wild type plants of Arabidopsis thaliana, plants overexpressing MiEFF18, or mutant plants (knockout) for the AtSmD1b gene, shows that this effector is able to modulate the function of the alternative splicing regulator SmD1 and that its overexpression modifies the expression of genes involved in the giant cell ontogenesis. MiEFF18 also modulates the function of the SmD1 protein in triggering a specific "silencing" pathway called S-PTGS (« sense transgene post-transcriptional gene silencing»). We were able to show that Arabidopsis thaliana, Solanum lycopersicum (tomato) and Nicotiana benthamiana plants in which the expression of SmD1 is affected exhibit increased resistance to root-knot nematodes and that the function of the effector EFF18 is conserved in other Meloidogyne species. EFF18 effectors are therefore able to manipulate the different functions of SmD1 in order to promote the formation of giant cells during infection in Arabidopsis and Solanaceae. In a second part, we were able to demonstrate the secretion of the MiPDI-1 effector in giant cells. A yeast two hybrid strategy made it possible to identify its plant target, the stress-associated protein 12 (SAP12) in tomatoes and A. thaliana. SAP12 is a protein capable of sensing the environment redox state and is involved in plant defense and the response to various abiotic stress. The functional analysis of this effector/target made it possible to show that the manipulation of the SAP12 protein by MiPDI-1 is essential for the parasitic success of M. incognita, in order to (i) protect the larvae of reactive oxygen species produced during the penetration of the host and (ii) to modulate the expression of genes involved in defense and the response to stress during parasitism. This work shows the importance of studying the molecular dialogue between the parasite and the host plant and the characterization of the proteins targeted by these pests for the development of new resistances against these parasites
Symbiose fixatrice d'azote versus nutrition minérale azotée : conséquence sur l'interaction entre Medicago truncatula et le puceron du pois Acyrthosiphon pisum by Gaurav Pandharikar( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Symbionts play a crucial role in shaping their host phenotype and driving its adaptation to the environment. However, until recently plant-insect interactions were studied disregarding the symbiotic bacterial presence in the involved partners. New findings have now demonstrated that above- and belowground plant communities are linked through biotic interactions. In this context, my PhD questions how the interaction between plant-insect species are modulated by their respective symbionts. In the first part of my work I have analysed the effect of the nitrogen fixing symbiosis (NFS) in the leguminous Medicago truncatula (A17) in interaction with pea aphid Acyrthosiphon pisum lines bearing different facultative endosymbionts (FS). For this, first I have compared the growth of M. truncatula plants either inoculated with the nodules inducing bacteria Sinorhizobium meliloti (NFS) or supplemented with nitrate (non-inoculated; NI), infested with pea aphid lines derived from the same genetic clone (YR2) and bearing either no FS or Hamiltonella defensa, Serratia symbiotica or Regiella insecticola. As expected, growth of both NFS and NI plants was reduced by the aphid attack, while aphid growth (but not survival) was strongly reduced on NFS compared to NI plants. Interestingly, most aphid lines decreased the plant nitrogen fixation capacity of NFS plants by inducing an early nodule senescence. Finally, in NFS plants all aphid lines triggered the expression of Pathogenesis Related Protein 1 (PR1), a marker of the salicylic (SA) pathway, and of Proteinase Inhibitor (PI), a marker of the jasmonic (JA) pathway, while in NI plants only PR1 expression was triggered. Thus, the plant symbiotic status influences clearly the plant-aphid interactions and the plant response while the aphid symbiotic status only modulates the response amplitude. Since both plant and aphid genotypes are important in the outcome of their interaction, I further studied how plant symbiosis affect the plant-insect genotype x genotype interaction. For this, I used three different pea aphid genotypes devoid of FS (LL01, YR2, and T3-8V1) and two M. truncatula genotype (A17 and R108) combinations in the presence or absence of rhizobacteria. The performance of each aphid genotype on both plant genotypes and the effect of different aphid genotypes on the plant growth and nitrogen fixation capacity of NFS plants were measured. We also estimated M. truncatula genotype-mediated defence response triggered by the different aphid genotypes using multiple gene markers of the JA and SA defence-pathways. I found that the plant-insect genotypes as well as the rhizobacteria presence significantly affect plant-aphid interactions. These results show that the outcome of the plant-insect interaction is strongly impacted by the genotype of the species and by their symbiotic status, rising a new level of complexity that remains to be explored
Maturation of nematode-induced galls in Medicago truncatula is related to water status and primary metabolism modifications( )

1 edition published in 2015 in English and held by 1 WorldCat member library worldwide

Highlights: Identification of metabolites in mature galls induced by M. incognita. Ionic content analyze presents gall specificity. The gall aging affects the metabolomic and ionic content. Evolution of water status during gall aging and correlation to metabolism changes. Abstract: Root-knot nematodes are obligatory plant parasitic worms that establish and maintain an intimate relationship with their host plants. During a compatible interaction, these nematodes induce the redifferentiation of root cells into multinucleate and hypertrophied giant cells (GCs). These metabolically active feeding cells constitute the exclusive source of nutrients for the nematode. We analyzed the modifications of water status, ionic content and accumulation of metabolites in development and mature galls induced by Meloidogyne incognita and in uninfected roots of Medicago truncatula plants. Water potential and osmotic pressure are significantly modified in mature galls compared to developing galls and control roots. Ionic content is significantly modified in galls compared to roots. Principal component analyses of metabolite content showed that mature gall metabolism is significantly modified compared to developing gall metabolism. The most striking differences were the three-fold increase of trehalose content associated to the five-fold diminution in glucose concentration in mature galls. Gene expression analysis showed that trehalose accumulation was, at least, partially linked to a significantly lower expression of the trehalase gene in mature galls. Our results point to significant modifications of gall physiology during maturation
Effet des bioinsecticides à base de Bacillus thuringiensis sur la physiologie intestinale de la Drosophile by Rouba Jneid( )

1 edition published in 2021 in French and held by 1 WorldCat member library worldwide

Microbes, toxins and chemicals such as pesticides are harmful agents that could attack the gastrointestinal tract throughout organismal life. This triggers a rapid renewing of damaged intestinal cells to sustain a functional barrier to limit the risk of developing pathologies. The repair process involves a transient proliferation of intestinal stem cells (ISCs) and the differentiation of their progeny into enterocytes to replace the damaged ones. Among pesticides, the broadly used bioinsecticides composed of spores and crystalline (Cry) toxins of Bacillus thuringiensis subsp kurstaki (Btk) are expected to supplant synthetic chemical pesticides to specifically fight lepidopteran pests. We have investigated here the effects of spores and toxins of Btk ingested along with the food on intestinal cellular homeostasis of the non-target dipteran Drosophila melanogaster. We showed that Btk Cry toxins induce enterocyte death and ISC proliferation. Surprisingly, a high proportion of ISC's daughter cells differentiate into enteroendocrine cells instead of their initial enterocyte destiny. This imbalanced intestinal cell composition is due to Cry toxins which weakened cell adhesion between the ISC mother cell and its immediate daughter progenitor leading the latter to adopt an enteroendocrine cell fate. Our results further showed that Cry1A family of toxins is implicated in this intestinal cell fate diversion, suggesting that Btk bioinsecticides induce non-negligible deleterious effects on gut physiology
Régulation de la sénescence des nodules chez Medicago truncatula by Li Yang( )

1 edition published in 2020 in English and held by 1 WorldCat member library worldwide

Les légumineuses peuvent s'associer aux rhizobia pour développer de nouveau un organe racinaire, la nodosité racinaire. La nodosité racinaire peut réduire l'azote atmosphérique en azote disponible pour l'hôte végétal. Ainsi, la symbiose fixatrice d'azote joue un rôle important dans l'agriculture avec des apports directs d'azote aux plantes cultivées. Dans la première partie de la thèse, nous avons caractérisé l'impact de la carence bactérienne en GSH sur la différenciation bactérioïde et le fonctionnement des nodules lors de l'interaction symbiotique entre Medicago truncatula et Sinorhizobium meliloti. Des marqueurs physiologiques, biochimiques, cellulaires et génétiques ont été utilisés pour décrire le nodule fonctionnant dix et vingt jours après l'inoculation de la plante. Nos résultats ont montré que la carence bactérienne en GSH n'affecte pas la différenciation bactérioïdienne. Cependant, elle induit un processus précoce de sénescence des nodosités chez M. truncatula. Au cours de la sénescence des nodosités, les activités protéolytiques sont augmentées et se terminent par la dégradation finale des bactéroïdes et des cellules végétales. Par conséquent, les protéases se révèlent être les enzymes caractéristiques de la sénescence des nodosités. Au début de la sénescence nodositaire, une cystéine protéase de la famille des papaïnes, MtCP6 est un bon marqueur moléculaire pour l'initiation de la sénescence des nodules. En ce qui concerne la deuxième partie de la thèse, une analyse consistant en une série de délétion du promoteur de MtCP6 a été réalisée pour identifier les séquences régulatrices présentes sur le promoteur CP6 et impliquées dans la sénescence nodulaire. Afin de comprendre la régulation transcriptionnelle de la sénescence nodositaire chez M. truncatula. Ensuite, la région cis-régulatrice identifiée (67 pb, NS) a été validée pour fonctionner dans l'activation de la transcription dans la zone nodulaire III-IV. Nous avons pu montrer que les tétramères de NS peuvent induire la transcription dans la zone de sénescence de la nodosité. Afin de déterminer l'importance de NS par rapport au promoteur complet (-1710 pb), une analyse fonctionnelle a été réalisée avec suppression de la boîte NS sur le promoteur complet et sur le promoteur minimal (-254 pb). De plus, la validation les rôles potentiels des motifs CAAT, WRKY et Dof localisés dans la séquence NS en 5' a été réalisée à l'aide de délétions sites spécifiques. Finalement, la technique de “yeast-one-hybrid” a été utilisée pour identifier des facteirs de transcription interagissant avec le fragment NS. Les résultats préliminaires sont présentés.Dans leur ensemble, les résulats permettent une meilleure compréhension de la régulation et du fonctionnement de la sénescence nodulaire
Étude de la régulation du transcriptome de nématodes parasites de plante, les nématodes à galles du genre Meloidogyne by Chinh Nghia Nguyen( )

1 edition published in 2016 in English and held by 1 WorldCat member library worldwide

Les nématodes à galles (RKN) du genre Meloidogyne spp. sont des parasites obligatoires des plantes qui induisent la formation d'un site nourricier spécialisé au sein des racines. Mon projet de thèse a pour objectif d'identifier des gènes spécifiques de ces nématodes qui sont impliqués dans le parasitisme en se focalisant sur des protéines sécrétées ou effecteurs. La technologie de séquençage Illumina a été utilisée pour comparer les transcriptomes de M. incognita au cours de son cycle de vie. A partir de 307 gènes surexprimés dans -au moins- un stade du cycle de vie, nous avons sélectionné 14 candidats d'effecteurs. Des expériences de RT-qPCR, d'hybridation in situ et d'ARN interférence ont permis de confirmer le profil d'expression, de localiser l'expression des effecteurs et d'étudier leur rôle dans la pathogénicité. Ce travail a permis de démontrer le rôle important d'une petite protéine, MiSCR1, dans les stades précoces du parasitisme. Parallèlement, nous avons réalisé l'assemblage de novo du transcriptome de M. enterolobii, qui représente une nouvelle menace pour l'agriculture mondiale du fait de sa capacité à se reproduire sur la majorité des plantes résistantes aux autres RKN. Les premières comparaisons avec d'autres RKN nous ont permis d'identifier, non seulement des effecteurs en commun, mais aussi ceux qui sont spécifiques à certaines espèces de RKN et qui pourraient expliquer des différences de gamme d'hôtes. En conclusion, les analyses de transcriptomes de RKN ont permis de caractériser des nouveaux effecteurs candidats impliqués dans la pathogénicité, et d'apporter de nouvelles connaissances pour le développement de méthodes de lutte contre ces bioagresseurs
 
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