Differential Selection on Carotenoid Biosynthesis Genes as a Function of Gene Position in the Metabolic Pathway: A Study on the Carrot and Dicots

Background: Selection of genes involved in metabolic pathways could target them differently depending on the position of genes in the pathway and on their role in controlling metabolic fluxes. This hypothesis was tested in the carotenoid biosynthesis pathway using population genetics and phylogenetics. Methodology/Principal Findings: Evolutionary rates of seven genes distributed along the carotenoid biosynthesis pathway

Etude comparee de Phytophthora megasperma (Dresch.) et Pythium violae (Ches. , Hick.) et de leurs relations avec la plante dans l'expression des symptomes de bague et de cavity spot sur carotte (Daucus carota)

SIGLEINIST T 73698 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

La redéfinition de la norme comme gestion du divers dans le droit à l'autodétermination de son corps

International audienc

Affect and Responsibility in family : philosophical and technical approach

Dans les rapports familiaux, les mécanismes de la responsabilité paraîssent s’appliquer plus difficilement qu’ailleurs. Qu’il s’agisse d’engager la responsabilité des époux, ou bien celle d’un parent envers son enfant, ou même encore de juger un délinquant passionnel, il peut être malaisé de déterminer les parts de responsabilité et de culpabilité qui reviennent à chacun. L’élément affectif, qui n’est pas regardé en principe comme un objet possible du droit, est susceptible d’expliquer cette difficulté. L’objet de cette thèse est donc de découvrir ce que peut être cet affect, et s’il intervient effectivement de façon significative dans les responsabilités familiales. Dans la pensée classique, l’affect n’a pas d’autonomie, en ce sens qu’il est toujours assimilé et réduit à d’autres notions, telles que l’émotion ou la volonté. En le dégageant de ces réductions, pourtant, l’affect peut être un élément isolable, qui est clairement identifiable dans le lien conjugal ou dans la filiation. L’affect est ainsi un élément concret, mais aussi dynamique, en ce sens qu’il est doté d’une valeur normative. Il est donc capable, non seulement d’éclairer des situations familiales pour lesquelles la responsabilité, civile ou pénale, doit être mise en oeuvre, mais encore de porter une valeur, que le droit peut découvrir et protéger.In family relations, responsibility mechanism seems to apply themselves with much more difficulty then elsewhere. Whether it engages the responsibility of the married couple, or the one of a parent towards his child, or even to judge a crime of passion, it can be difficult to determine the responsibility or guilt of each party. The affectif element, that is usually not considered like a text of law, is likely to explain this difficulty. Therefore, the purpose of this thesis is to discover what can be this affect, and if it indeed intervenes in a significant way in family responsibilities. In the classical thought, the affect has no autonomy, in a way that it is always assimilated and reduced to other notions such as emotion or free will. Removing these simplifications, the affect can be an element which can be isolated and clearly identified in the conjugal link or in filiation. Consequently, the affect is a concret element, but also dynamic, in the way it is doted by a normative value. It is therefore able, not only to enlighten family situations for which, civil or penal responsibility must be applied, but must also carry a value, that law may discover and protect

Bases moléculaires de la floraison chez le rosier

Chez les plantes polycarpiques, le contrôle moléculaire de la floraison est encore peu connu, contrairement aux plantes monocarpiques comme Arabidopsis thaliana avec notamment l'implication des acides gibbérelliques (GA). Chez le rosier, les GA inhibent la floraison uniquement chez les génotypes non remontants. La remontée de floraison pourrait être expliquée par une régulation différente des gènes de l'initiation florale impliquant des gènes déjà décrits ou bien des gènes qui ne serait pas encore connus. L'objectif de cette thèse est de rechercher et caractériser les gènes impliqués dans le contrôle de la floraison et plus particulièrement de la remontée de floraison chez le rosier. L'initiation florale est étudiée au niveau phénotypique et moléculaire chez quatre génotypes de rosiers, dont un couple de mutants pour la remontée de floraison. Par une approche gène candidat, des homologues de gènes de floraison sont isolés chez le rosier. De nouveaux candidats sont recherchés par une approche différentielle...In perennial plants, molecular control of flowering is still poorly understood. Up to now, flowering control is well described in monocarpic model plants like Arabidopsis thaliana. Gibberellic acids (GA) pathway play an important role in flowering time in monocarpic and physiological study shows that GA inhibit blooming only in non recurrent roses. Recurrent blooming might be explained by a different regulation of floral initiation gene networks using the same known genes or it might involve new unknown genes. The objectives of this work are to isolate and characterise the genes involved in the control of flowering and more precisely of recurrent blooming in rose. Floral initiation is studied at the phenotypic and molecular level in four different genotypes, two of them are a pair of mutants for recurrent blooming. Using a candidate gene approach, we isolated flowering genes, and new candidates are looked for by differential display experiment.ANGERS-BU Lettres et Sciences (490072106) / SudocSudocFranceF

Caractérisation des déterminants génétiques et moléculaires de la résistance à Alternaria dauci chez la carotte

La brûlure, due à Alternaria dauci, est la maladie foliaire la plus préjudiciable sur carotte, qu'il s'agisse de production de racines ou de semences. Développer des variétés présentant un niveau de résistance fort et durable est l'un des objectifs principaux des sélectionneurs de l'espèce. Le présent travail a permis d'y contribuer en caractérisant les facteurs de résistance impliqués.Deux familles d'individus en ségrégation pour ce caractère ont fait l'objet, d'une part, d'un phénotypage sur descendances F3 en tunnel (contamination artificielle) et au champ (infestation naturelle) et, d'autre part, d'un génotypage grâce à des marqueurs AFLP, ISSR, APF-RGA. Les deux cartes génétiques obtenues (1367.6 cM et 1570.2 cM) ont un espacement moyen des marqueurs de 7.5 cM.Le logiciel QTLCartographer, a permis de détecter un total de 16 QTL significatifs dont deux expliquent 17 et 24 % de la variation phénotypique totale. Parmi ceux-ci, 10 ont été détectés pour la 1ère date de notation. La phase de l'installation de la maladie pourrait donc être la plus discriminante pour la sélection phénotypique. Au contraire, les QTL détectés pour les 2ème et 3ème dates de notation, généralement avec un R2 plus faible que pour ceux de la 1ère date, pourraient être impliqués dans la limitation de l'invasion de l'hôte par le pathogène ou dans le phénomène de régénération du feuillage.Par ailleurs, une nouvelle procédure d'évaluation de la résistance basée sur un test plante entière est proposée. Enfin, les résultats ont mis en évidence la complémentarité de plusieurs approches moléculaires pour augmenter la saturation de cartes génétiques chez la carotte.Alternaria leaf blight is the most important foliar disease on carrot, cultivated for root production as well as seed production. High and sustainable resistance is one of the most important objectives of breeding programs. The present work is a contribution to the characterisation of resistance factors. Two segregating populations were submitted to evaluation following artificial or natural inoculation on one hand, and to genotyping with AFLP, ISSR, APF-RGA markers, on the other hand. Two genetic linkage maps were generated (1367.6 cM et 1570.2 cM) with an average spacing of 7.5 cM between markers.A total of 16 significant QTL were detected using QTLCartographer software. Ten were detected for the first evaluation date, among which two explained 17 and 24% of the total phenotypical variation. Therefore, the host/pathogen recognition could be the most discriminating phase for phenotypical breeding. The QTL detected for the second and third evaluation dates, with a lower R , could be related to invasion control or to foliage regeneration. Moreover, a new procedure for resistance evaluation based on a whole plant test was proposed. Finally, results showed a complementarity between several molecular methods for linkage map saturation within carrot.ANGERS-BU Lettres et Sciences (490072106) / SudocSudocFranceF

Etude de la diversité pigmentaire chez la carotte pour la création de nouvelles variétés axées sur leurs qualités

Etude de la diversité pigmentaire chez la carotte pour la création de nouvelles variétés axées sur leurs qualitésEtude de la diversité pigmentaire chez la carotte pour la création de nouvelles variétés axées sur leurs qualité

Evaluation of carrot resistance to alternaria leaf blight in controlled environments

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceThe objective of this study was to find a technique for plant resistance screening to alternaria leaf blight (ALB), caused by the fungus Alternaria dauci, in controlled environments. Glasshouse and laboratory screening methods were compared using three cultivars and F-2 genotypes segregating for ALB resistance evaluated against self-pollinated F-3 field-grown plants. Plant disease was assessed through a disease index obtained from the size and number of symptoms on carrot leaves. The results indicated the value of glasshouse evaluation and the inadequacy of detached leaf and hypocotyl assays for carrot screening for ALB resistance. Spearman's rank correlation, applied to results obtained with both F-2 plants and their progeny, indicated that the optimal evaluation stage for ALB resistance in carrot is 20 days after inoculation. This test was powerful enough to be used as a prescreening test in breeding programme

Exploring plant defense pathways in the carrot-Alternaria dauci pathosystem, a non-model interaction

Communication (Communication avec actes dans un congrès)Most of the molecular mechanisms underlying plant partial resistance QTLs are still unknown. Twocompeting hypothesis are generally invoked to link observed field resistance with actual moleculargene function. An older hypothesis links partial resistance QTLs with overcome typical R genesencoding classical NBS-LRR or LRR-TM type proteins. In a recent paper (Hu et al., 2008), partial plantresistance was linked with defense mechanisms. These results led us to develop a candidate geneapproach to study partial plant resistance of carrot (Daucus carota) towards its main foliar fungalpathogen, Alternaria dauci. Since carrot is a non-model plant, little sequence data is available onpublic databases. We thus chose to develop a homology-based cloning strategy in order to detectand sequence defense-related genes in carrot. Since A. dauci is a necrotrophic pathogen, we focusedthis strategy on Jasmonic acid (JA) signaling pathway and JA controlled defense genes (such as JAZ3or PR4). Since the degenerate primer strategy is not known to be effective on each and every gene,we chose to apply it in a parallel fashion on a rather large set of genes. Alignments of sequence datafrom eight already sequenced dicotyledonous plant species were performed for 15 genes.Degenerate primers were defined for 10 genes involved in this JA pathway. Additionally, we defineddegenerate primers for two defense genes that are not mainly JA- regulated: the SA-regulateddefense gene PR1, and the non host defense gene PAL1. Five out of 12 genes were partially clonedand sequenced. Two strategies are currently deployed to link these defense related genes withpartial resistance QTLs observed in the carrot-A. dauci interaction (Le Clerc et al., 2009). SNPs arebeing found between the resistant and susceptible parents of our mapping populations. They willhelp us to find potential QTL-candidate co-localizations. Absence of such a co-localization does notmean that a potential candidate is not involved in defense. It is also possible that the QTL influencesdefense-related genes activation rather than the efficiency of the cognate PR proteins. For thisreason, we also plan to study the induction of these genes by A. dauci in both susceptible andresistant backgrounds.</p

Impact of carrot resistance on development of the Alternaria leaf blight pathogen (Alternaria dauci)

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienceThe interaction between Alternaria dauci and two carrot cultivars differing in their resistance to leaf blight was investigated by microscopy. The fungal development between 1 and 15 days post-inoculation was quite similar in the susceptible cv. Presto and the partially resistant cv. Texto: After conidial germination, leaf adhesion of the pathogen was achieved with mucilaginous filaments; hyphae penetrated the leaves directly with/without the formation of appressoria-like structures or via stomata; the fungus spread by epiphytic hyphae with hyphopodia and subcuticular mycelia. Intense necrotic plant cell reactions occurred under the fungal structures. At 21 days post-inoculation, typical features of fungal development were noted for each cultivar: growing hyphae emerged from stomata in cv. Presto, whereas conidiophores without conidia were observed in cv. Texto. Leaf tissues of both cultivars were strongly damaged and vesicle-like structures (assumed to be plant phenolics) were abundantly present between mesophyll cells. A real-time PCR method was developed for in planta quantification of A. dauci. Between 1 and 15 days post-inoculation, the fungal biomass was equivalent in the two cultivars and was about fourfold higher in cv. Presto than cv. Texto at 21 and 25 days post-inoculation. Taken together, our results indicated that A. dauci was able to colonize both cultivars in a similar manner during the first steps of the interaction, then fungal development in the partially resistant cultivar was restricted due to putative plant defence reactions. The results of this study enhance the overall understanding of infection processes in the A. dauci-carrot pathosyste