Involvement of Arabidopsis BIG protein in cell death mediated by Myo- Inositol homeostasis

International audienc

The seco-iridoid pathway from Catharanthus roseus

The (seco)iridoids and their derivatives, the monoterpenoid indole alkaloids (MIAs), form two large families of plant-derived bioactive compounds with a wide spectrum of high-value pharmacological and insect-repellent activities. Vinblastine and vincristine, MIAs used as anticancer drugs, are produced by Catharanthus roseus in extremely low levels, leading to high market prices and poor availability. Their biotechnological production is hampered by the fragmentary knowledge of their biosynthesis. Here we report the discovery of the last four missing steps of the (seco)iridoid biosynthesis pathway. Expression of the eight genes encoding this pathway, together with two genes boosting precursor formation and two downstream alkaloid biosynthesis genes, in an alternative plant host, allows the heterologous production of the complex MIA strictosidine. This confirms the functionality of all enzymes of the pathway and highlights their utility for synthetic biology programmes towards a sustainable biotechnological production of valuable (seco)iridoids and alkaloids with pharmaceutical and agricultural applications

Phénotypage métabolique des réponses aux stress abiotiques chez Arabidopsis thaliana (analyse fonctionnelle et intégrative du métabolome)

Les stress abiotiques (températures extrêmes, salinité, sécheresse) ont un impact négatif sur la croissance et le développement végétal et constituent un défi agronomique majeur. La compréhension des réponses mises en œuvre par différentes espèces de plantes est un volet incontournable de toute stratégie d'amélioration variétale, mais offre aussi un modèle de choix pour l'étude intégrative de mécanismes qui opèrent à différents niveaux d'organisation biologique, selon des modalités hautement régulées. L'abondance de collections de génotypes et le progrès des outils d'analyse moléculaires, couplés à des traitements bioinformatiques performants, ont ouvert la perspective de caractériser la plasticité phénotypique de plantes modèles à l'échelle génomique et dans un contexte environnemental dynamique. La métabolomique en particulier, définie comme l'analyse quantitative non ciblée des métabolites d'un échantillon biologique, accède au cœur de nombreux processus physiologiques tels que la nutrition, l'adaptation biochimique et ultrastructurale ou la signalétique cellulaire. Les travaux réalisés constituent une approche de la physiologie du stress chez l'espèce considérée sensible /Arabidopsis thaliana/, par l'analyse du métabolome primaire dans une perspective exploratoire, diagnostique et corrélative.Abiotic stresses (extreme temperatures, salinity, drought) impair plant growth and development and are important agronomic challenges. Understanding stress responses developed by various species contributes to crop improvement and also constitutes an interesting approach of integrated mechanisms operating at different organisation levels in highly regulated ways. Availability of genotypes collections, molecular analysis tools and efficient bioinformatics pave the way to phenotyping of model plants at the genomic scale, in relation with their environment. Metabolmics, defined as unbiaised, nontargeted and exhaustive analysis of metabolites in biological samples, provide new insights into physiological processes like nutrition, biochemical and structural adaptation or cell signalling. Present work is an exploratory, diagnostic and correlative approach of primary metablome in the stress sensitive species Arabidopsis thaliana.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Le sel dans le Rwanda ancien

Salt in Former Rwanda. During the pre-Colonial period, salt was, in Rwanda as in all of Central Africa, a rare and much sought after food product. Because they were unable to procure quality salt in Katwe, the majority of the population of former Rwanda was obliged to have recourse to local production, which had a plant base. Lacustrine salt and salt produced locally was found in the commercial network that existed round the market places and which was supplied by peddling.Au Rwanda comme dans toute l'Afrique centrale le sel était, à l'époque précoloniale, une denrée rare et recherchée. Faute de pouvoir se procurer le sel de qualité récolté à Katwe, la majorité de la population du Rwanda ancien avait recours à des productions locales à base de végétaux. Le sel lacustre et le sel produit localement se retrouvaient sur les circuits d'échange qui s'articulaient autour des marchés et qui étaient relayés par le colportage.Lugan Bernard, Mutombo Raphaël. Le sel dans le Rwanda ancien. In: Cahiers d'outre-mer. N° 136 - 34e année, Octobre-décembre 1981. pp. 361-384

Etude de profilage métabolique des réponses au stress salin chez Arabidopsis thaliana

Communication oral

Increased metabolic fluxes in tomato stems infected by Botrytis cinerea

International audienc

Effects of diet and salinity on the survival, egg laying and metabolic fingerprints of the ground-dwelling spider Arctosa fulvolineata (Araneae, Lycosidae)

International audienceSoil salinity and the salinity of trophic resources may alter the osmoregulatory processes of arthropod, challenging the smooth regulation of body water, and, ultimately, survival. The intra and extracellular build-up of osmolytes represent a common strategy to attenuate acute hyperosmotic stress in several arthropod species. In the present study, we aimed to determine the impact of substrate and trophic resource salinities on salt tolerance in the female wolf spider, Arctosa fulvolineata, which is considered a specialist salt marsh species. We evaluated adult female survival and egg laying, and quantified the osmo-induced accumulation of compatible solutes (GC-MS). Three concentrations of substrate salinity were tested (0‰, 35‰ and 70‰) under three trophic conditions (starved spiders, spiders fed with salt prey [intertidal amphipods] and spiders fed with unsalted prey [freshwater amphipods]). We found no support for diet preferences in female A. fulvolineata, which exhibited similar predation rates on freshwater and marine amphipods. Survival and egg-laying were significantly impaired when female A. fulvolineata were exposed to hypersaline conditions for 12 days. Our results showed an increase in the level of several compatible solutes when spiders were exposed for 12 days to saline conditions. For instance, α-alanine, β-alanine, arginine, asparagine, aspartate, homoserine, glutamine, glycine, proline and serine levels were 4-10 times higher under hypersaline conditions. The osmo-induced accumulation of amino acids may increase the osmolality of body fluids, thus enhancing the smooth regulation of body fluids and survival ability of wolf spider under extreme saline conditions

Increased metabolic fluxes in tomato stems infected by Botrytis cinerea

International audienc