Intraspecific Competition in Lucerne and Relationships with Reserve Availability

Below-ground reserves are thought to provide an indication of a forage potential for shoot regrowth after defoliation. The aim of this work was to re-evaluate the causal relationships existing between organic reserves (non-structural carbohydrates and N reserves) and shoot regrowth of alfalfa. The variations brought about by cultivar differences (cv Lodi or Europe), length of the previous regrowth period (30 or 45 d), or by intraspecific competition for light within a dense canopy, were studied. Field grown plants were harvested at weekly intervals, and separated as dominant, intermediate and suppressed plants. Shoot regrowth yield was determined and taproot were analyzed for starch, N, soluble proteins and vegetative storage proteins. Results showed that taproot starch and N contents were modified by the length of the previous regrowth but not by the position of the plant within the canopy. Soluble protein or VSP concentrations increased with the length of the previous regrowth, and with a higher position of the plant within the canopy. Shoot regrowth yield was linearly related to taproot soluble protein and VSP contents on day of defoliation, but relationships were not found with initial starch or N contents. These results suggest that root protein and VSP are key organic nutrient for alfalfa shoot regrowth after harvest

Plant N Fluxes and Modulation by Nitrogen, Heat and Water Stresses: A Review Based on Comparison of Legumes and Non Legume Plants

Chapter 5International audienc

Copper-deficiency in Brassica napus induces copper remobilization, molybdenum accumulation and modification of the expression of chloroplastic proteins

During the last 40 years, crop breeding has strongly increased yields but has had adverse effects on the content of micronutrients, such as Fe, Mg, Zn and Cu, in edible products despite their sufficient supply in most soils. This suggests that micronutrient remobilization to edible tissues has been negatively selected. As a consequence, the aim of this work was to quantify the remobilization of Cu in leaves of Brassica napus L. during Cu deficiency and to identify the main metabolic processes that were affected so that improvements can be achieved in the future. While Cu deficiency reduced oilseed rape growth by less than 19% compared to control plants, Cu content in old leaves decreased by 61.4%, thus demonstrating a remobilization process between leaves. Cu deficiency also triggered an increase in Cu transporter expression in roots (COPT2) and leaves (HMA1), and more surprisingly, the induction of the MOT1 gene encoding a molybdenum transporter associated with a strong increase in molybdenum (Mo) uptake. Proteomic analysis of leaves revealed 33 proteins differentially regulated by Cu deficiency, among which more than half were located in chloroplasts. Eleven differentially expressed proteins are known to require Cu for their synthesis and/or activity. Enzymes that were located directly upstream or downstream of Cu-dependent enzymes were also differentially expressed

Contribution a l'etude du metabolisme de l'azote chez le ray-grass anglais en depart de croissance apres une coupe

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Modelling of nitrate uptake, N translocation and remobilisation based on short term 15N labelling in Brassica Napus L.

International audienc

Modélisation de l'absorption de l'azote nitrique, de son allocation et de sa remobilisation chez le colza d'hiver (Brassica napus L.) de la reprise de la végétation au stade maturité des graines

PARIS-AgroParisTech Centre Paris (751052302) / SudocSudocFranceF

Mise en réserve d'azote sous forme de protéines de réserve des organes végétatifs (VSP) chez medicago sativa L. et brassica napus L. : principaux facteurs de régulation

Chez la luzerne (Medicago sativa L.) et le colza (Brassica napus L.), des protéines de réserve des organes végétatifs (VSP : vegetative storage protein) accumulées dans le pivot sont fortement impliquées dans la fourniture et le stockage d'azote. L'accumulation des VSP sous l'effet d'une héméropériode courte ou d'une application de méthyl-jasmonate, chez la luzerne ou au cours du développement chez le colza, résulterait d'une action directe (induction des gènes) et indirecte (via la modification des relations source-puits pour l'azote). Chez la luzerne, alternativement à leur fonction de réserve, les VSP pourraient avoir un rôle dans la survie hivernale et la protection contre les pathogènes, comme l'atteste la découverte récente d'une homologie de séquence de l'une des VSP avec des chitinases. Chez le colza, la VSP pourrait constituer une réserve azotée "tampon" révélatrice du changement de statut source-puits pour l'azote de la plante et posséder ainsi un rôle qualitatif.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

REMPLISSAGE EN AZOTE DES TISSUS REPRODUCTEURS DE BRASSICA NAPUS L. (ESTIMATION DES FLUX PAR MARQUAGE ISOTOPIQUE, CARACTERISATION DES PROTEINES IMPLIQUEES DANS LA MISE EN RESERVE ET DES FACTEURS INDUISANT LEUR ACCUMULATION)

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Structure génétique des populations de saumon Atlantique en France

Cette thèse étudie la distribution spatiale de la diversité génétique des populations françaises de saumon Atlantique, s intéressant notamment à l effet de facteurs environnementaux et des repeuplements. 1739 individus échantillonnés dans 34 rivières françaises et provenant de cohortes anciennes (à partir 1965) et récentes ont été génotypés à 17 marqueurs microsatellites. Les résultats montrent l existence de cinq groupes de populations génétiquement et géographiquement distincts. La distance côtière entre les populations ainsi que la longueur des rivières expliquent largement la structure observée. La grande taille des poissons adultes de l Allier, ainsi que la différenciation importante de cette population inféodée à des sites de frais très éloignés de la mer suggèrent une adaptation locale à la difficulté de montaison. La comparaison des échantillons anciens et récents montre des taux d introgression variables par les souches utilisées pour les repeuplements. Dans certaines rivières dépeuplées et non sujettes au repeuplement, nous avons observé des recolonisations spontanées par des poissons provenant de stocks voisins ou distants. Afin de quantifier l impact des repeuplements dans les populations de la baie du Mont-Saint-Michel, nous avons développé des simulations individus centrées dont les résultats suggèrent une faible survie des poissons déversés. Enfin, nous avons également réalisé des analyses microchimiques sur les otolithes d individus issus de populations repeuplées. Le couplage des analyses microchimiques et génétiques a permis de déterminer si les poissons ayant des caractéristiques génétiques de pisciculture provenaient de repeuplement ou de reproduction in natura de poissons précédemment déversés.This thesis investigates the genetic structure among Atlantic salmon populations from France. We more specifically studied the influence of environmental factors and stocking on the spatial distribution of genetic diversity. We genotyped at 17 microsatellite markers 1739 individuals from 34 French rivers, from old (1965-1987) and recent (1998-2006) cohorts. Analyses of recent samples classed individuals into five genetically and geographically distinct groups. Distance among estuaries and river length were strong predictors of population structure. Moreover, the positive trend between body size and river length and the higher differentiation of the population having farthest spawning grounds off the river mouth suggest local adaptation to upstream migration difficulty. Comparison of recent and old samples showed a general reduction of differentiation among populations and some high introgression rates most probably resulting from stocking. In some depopulated rivers were no stocking was performed we observed natural recolonization by fish from neighbouring and distant stocks. To quantify the impact of stocking on some populations for which it was precisely documented, we developed an approach using temporally explicit simulations. This study suggests low fitness of stocking fish. In parallel to genetic analyses, we carried on microchemistry analyses of otolith from some fish from stocked populations. Coupling genetic and microchemistry analyses on the same individuals allowed identifying river-born fish with hatchery pedigrees, discriminating them from hatchery-born fish with same genetic characteristics.CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Etude et modélisation des effets de l'intensité de la coupe et du niveau des réserves organiques initiales sur la dynamique de l'azote et du carbone au cours de la repousse chez la luzerne (Medicago sativa L.)

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF