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The English walnut (Juglans regia L.) is the main species cultivated for the production of edible nuts. Due to heterozygosis, the characteristics of agronomical interest of walnut cultivars are not inherited via seed propagation. In vitro plant tissue culture thus plays a key role in mass propagation of high-quality walnut rootstocks. Micropropagation of walnut explants needs an ex vitro acclimatization phase to repair the in vitro induced abnormalities, and further requires a post-acclimatization growth in greenhouse conditions when plantlets become photoautotrophic. However, poor survival and slow growth rates are common difficulties encountered in nurseries when establishing micropropagated walnut saplings. As many other fruit and nut bearing trees, walnut exhibits a high dependency on symbiotic soil-borne arbuscular mycorrhizal (AM) fungi for development due to a coarse root architecture that limits soil inorganic phosphate (Pi) uptake. In the context of rootstock production, we investigated at different development stages the establishment of seven walnut rootstocks of economic interest, upon inoculation or not with an AM fungus and two contrasting Pi fertilization regimes. We demonstrated that biotization with the AM fungus Rhizophagus irregularis decrease micropropagated walnut rootstock dependency on Pi fertilization both at the acclimatization and post-acclimatization stages, together with improving adequate sapling development and quality, especially in the hybrid rootstocks VLACH, VX211, and WIP3. We also showed that these benefits are rootstock-dependent, indicating that walnut mycorrhizal dependency for Pi nutrition varies between cultivars, and that the symbiotic program may be differentially recruited depending on the chosen rootstock.

Ectopic expression of defensins in plants correlates with their increased capacity to withstand abiotic and biotic stresses(Carvalho & Gomes, 2011). However, few studies have explored the effects of decreased plant endogenous defensin transcripts on these stress responses.When over-expressed in Arabidopsis thaliana, some of the seven members of thePlant Defensin type 1 family (PDF1) are recognised to improve plant responses tonecrotrophic pathogens(De Conincket al.,2010)and increase seedling tolerance to excess zinc (Zn;Mirouzeet al., 2006). We carried out an extensive physiological and biochemical comparative characterisation of i) novel transgenic amiRNA lines silenced for the five most similarAtPDF1s, and ii) a double null mutant for the two most distant AtPDF1s. Silencing of fiveAtPDF1transcripts was specifically associated with increased aboveground dry mass production in mature plants under Zn excess conditions, and with increased plant tolerance to different pathogens–one fungus, one oomycete and one bacterium.These unexpected results challenge the current paradigm describing the role ofPDFs in the plant response to stresses.Additional roles of plant defensins are discussed, which open onto new perspectives for their functions(Nguyen et al., submitted).

The present invention relates to the use of 2-phenylbutyric acid or 3-phenylbutyric acid or 4-phenylbutyric acid, or a salt thereof, or a combination thereof, to combat cryptogamic diseases which are caused by fungi or oomycetes. The present invention also relates to the use of these compounds and these combinations as fungicidal or fungistatic agents in preventing or curing cryptogamic diseases., La présente invention concerne l'utilisation de l'acide 2-phénylbutyrique, ou de l'acide 3-phénylbutyrique, ou de l'acide 4-phénylbutyrique, ou de l'un de leurs sels, ou de l'une de leurs combinaisons, pour lutter contre les maladies cryptogamiques causées par les champignons et les oomycètes. La présente invention porte également sur l'utilisation de ces composés et de ces combinaisons comme agents fongicides ou fongistatiques pour la prévention ou le traitement curatif de maladies cryptogamiques.

International audience; We examine the influence of the acquirer’s reputation on investors’ reaction following the announcement of cross-border mergers and acquisitions. Drawing on signaling theory, we argue that the reputation sends a positive signal to investors when such deals are announced. Our empirical study is based on 134 cross-border M&As conducted by French multinationals. Our results confirm that reputation is positively related to M&A short-term value creation. However, the positive reaction of investors to the announcement of mergers and acquisitions is weaker for the most reputable companies. In addition, we show that the relationship between reputation and value creation is negatively moderated by the acquirer’s diversification strategy.; Estudiamos la influencia de la reputación del adquiriente sobre la reacción de los inversionistas frente al anuncio de fusiones y adquisiciones internacionales. Basándonos en la teoría de la señal, sugerimos que la reputación envía una señal positiva a los inversionistas al anunciarse este tipo de transacciones. Nuestro estudio empírico utiliza información de 134 fusiones y adquisiciones internacionales de empresas multinacionales francesas. Nuestros resultados confirman que la reputación aumenta la creación de valor asociada a las fusiones y adquisiciones en el corto plazo. Sin embargo, la reacción positiva de los inversionistas ante el anuncio de las fusiones y adquisiciones es menos fuerte para las empresas más reputadas. Además, mostramos que la estrategia de diversificación del sector del adquiriente modera negativamente la relación entre la reputación y la creación de valor.; Nous examinons l’influence de la réputation de l’acquéreur sur la réaction des investisseurs suite à l’annonce de fusions-acquisitions internationales. En nous appuyant sur la théorie du signal, nous avançons que la réputation envoie un signal positif aux investisseurs lorsque de telles opérations sont annoncées. Notre étude empirique est fondée sur 134 fusions-acquisitions internationales réalisées par des entreprises multinationales françaises. Nos résultats confirment que la réputation est positivement liée à la création de valeur à court terme des fusions-acquisitions. Toutefois, la réaction positive des investisseurs à l’annonce de fusions-acquisitions est de moindre intensité pour les entreprises les plus réputées. De plus, nous montrons que la relation entre réputation et création de valeur est négativement modérée par la stratégie de diversification sectorielle de l’acquéreur.