Is growing buckwheat allelopathic?

The growth repressive effect of common buckwheat (Fagopyrum esculentum) on redroot pigweed (Amaranthus retroflexus) was studied by separating resource competition from root interactions between the two plant species in a pot trial in the phytotron. In order to verify this result in situ field trials were performed. A strong repression of redroot pigweed growth by buckwheat could be observed independently of shading. However, soil both from the field and phytotron trials in which buckwheat had been growing didn’t have an effect on redroot pigweed and lettuce (Lactuca sativa) growth. Assuming that allelopathic compounds are present in the soil solution supplementary experiments were conducted. Lettuce root length was measured after exposing seeds to different “buckwheat soil” extracts. Moreover, buckwheat and lettuce developed at the same time next to each other in petri dishes. In none of the experiments an influence on lettuce and redroot pigweed development could be observed. We conclude that there are either no allelopathic molecules in the soil solution (not soluble in water) or that they are rapidly degraded. The observed growth inhibiting effect seems to be due to a long term and constant exposure of small quantities of allelopathic molecules. However, it is also possible that growth repression of redroot pigweed by buckwheat is not due to allelopathy. Ist wachsender Buchweizen allelopatisch?Echter Buchweizen (Fagopyrum esculentum) unterdrückt das Wachstum von Zurückgebogenem Amarant (Amaranthus retroflexus). Dieser Effekt wurde in einem Topfversuch im Phytotron untersucht, indem die Konkurrenz um Ressourcen von den Wurzelinteraktionen zwischen den beiden Pflanzenarten getrennt wurde. Um dieses Ergebnis zu verifizieren, wurden in situ-Feldversuche durchgeführt. Eine starke, von der Beschattung unabhängige, Wachstumsunterdrückung von Amarant durch Buchweizen konnte beobachtet werden. Allerdings hatte Erde, in der Buchweizen gewachsen war, sowohl aus dem Feldversuch als auch aus einem Phytotron-Versuch, keinen Einfluss auf das Wachstum von Amarant und Salat (Lactuca sativa). Unter der Annahme, dass allelopathische Verbindungen in der Bodenlösung vorhanden sind, wurden zusätzliche Experimente durchgeführt: Salatsamen wurden verschiedenen Extrakten von „Buchweizen-Erde“ ausgesetzt um anschließend die Länge der Salatwurzeln zu messen. Ausserdem wurden Buchweizen und Salat gleichzeitig nebeneinander in Petrischalen angezogen. In keinem der Versuche konnte ein Effekt auf die Entwicklung von Amarant und Salat beobachtet werden. Wir schliessen daraus, dass in der Bodenlösung entweder keine (wasserlöslichen) allelopathischen Verbindungen sind oder, dass sie rasch abgebaut werden. Der beobachtete wachstumshemmende Effekt scheint durch das Vorhandensein konstant kleiner Mengen an allelopathischen Verbindungen, die über einen langen Zeitraum hinweg vorhanden sind, hervorgerufen zu werden. Allerdings ist es auch möglich, dass die Wachstumsunterdrückung von Amarant durch Buchweizen nicht auf allelopathische Effekte beruht

Réinventer l’institution parlementaire européenne

Cet article offre un éclairage sur la réinvention de l’institution parlementaire communautaire à la suite de l’introduction du suffrage universel direct en 1979. Il analyse la stratégie discursive des élus et de leur présidente, Simone Veil, qui firent valoir leur nouvelle légitimité démocratique pour asseoir leur autorité face aux fractions des élites européennes associées aux autres institutions communautaires ou à d’autres institutions transnationales. Il montre aussi comment les nouveaux élus mobilisèrent diverses ressources pour renforcer leur stratégie de légitimation : leurs compétences budgétaires limitées, mais aussi les visites et voyages officiels orchestrés par leur présidente et leur engagement sur un thème porteur dans l’opinion, les droits de l’Homme.This article shows how members of the European Parliament (EP) endeavoured to reinvent the EP after the introduction of direct election in 1979. It analyses the discursive strategy of EP members and EP President Simone Veil, who invoked their new democratic legitimacy to assert themselves vis-à-vis other Community and transnational European institutions. It also highlights how they marshalled their resources – their limited budgetary powers, the ritual of official visits and their commitment to an increasingly salient theme, namely, human rights – in order to strengthen their authority and their legitimacy

The fou2 Gain-of-Function Allele and the Wild-Type Allele of Two Pore Channel 1 Contribute to Different Extents or by Different Mechanisms to Defense Gene Expression in Arabidopsis

The fatty acid oxygenation up-regulated 2 (fou2) mutant in Arabidopsis thaliana creates a gain-of-function allele in a non-selective cation channel encoded by the Two Pore Channel 1 (TPC1) gene. This mutant genetically implicates cation fluxes in the control of the positive feedback loop whereby jasmonic acid (JA) stimulates its own synthesis. In this study we observed extensive transcriptome reprogramming in healthy fou2 leaves closely resembling that induced by treatment with methyl jasmonate, biotic stresses and the potassium starvation response. Proteomic analysis of fou2 leaves identified increased levels of seven biotic stress- and JA-inducible proteins. In agreement with these analyses, epistasis studies performed by crossing fou2 with aos indicated that elevated levels of JA in fou2 are the major determinant of the mutant phenotype. In addition, generation of fou2 aba1-5, fou2 etr1-1 and fou2 npr1-1 double mutants showed that the fou2 phenotype was only weakly affected by ABA levels and unaffected by mutations in NPR1 and ETR1. The results now suggest possible mechanisms whereby fou2 could induce JA synthesis/signaling early in the wound response. In contrast to fou2, transcriptome analysis of a loss-of-function allele of TPC1, tpc1-2, revealed no differential expression of JA biosynthesis genes in resting leaves. However, the analysis disclosed reduced mRNA levels of the pathogenesis-related genes PDF1.2a and THI2.1 in healthy and diseased tpc1-2 leaves. The results suggest that wild-type TPC1 contributes to their expression by mechanisms somewhat different from those affecting their expression in fou

Microbial life in the grapevine: what can we expect from the leaf microbiome?

Recent studies have shown that plants harbor complex bacterial communities, the so- called “microbiome”. We are only beginning to unravel the origin of these bacterial plant inhabitants, their community structure and their roles, which, in analogy to the gut microbiome, are likely to be of essential nature. The aim of this work was to analyze the abundance and diversity of the cultivable members of the bacterial microbiome living in and on the leaves of grapevine, and to identify microbiome members with putative plant-protective activities against phytopathogenic organisms.Methods and results: Grapevine leaves were sampled three times during the growing season at one location and used to quantify the abundance and isolate representative members of the epiphytic and endophytic bacterial communities. Results were compared for three grapevine cultivars: Pinot noir, Chasselas and Solaris. Greater bacterial abundance and diversity was observed among epiphytes than among endophytes. Leaf imprints revealed a higher colonization density for the upper than for the lower surface of leaves. A high relative frequency of strains belonging to the genera Staphylococcus and Bacillus was observed, especially in the endophytic communities.Conclusions: The first results of this ongoing study led to the conclusion that epiphytic bacteria of the cultivable grapevine microbiome were more abundant and diverse than endophytic bacteria. A tendency towards more abundant bacteria in the resistant variety Solaris than in the susceptible varieties Chasselas and Pinot noir contrasted with a higher diversity of epiphytic bacteria in the Pinot noir variety. A trend for higher frequency of strains showing antagonistic activity towards the grapevine pathogen Botrytis cinerea among isolates from the resistant variety Solaris could indicate a putative contribution of microbiome bacteria to this resistant phenotype, even though this remains to be confirmed.Significance and impact of the study: This study constitutes a first step in characterizing the endo- and epiphytic cultivable bacterial communities of three grapevine varieties grown at the same location. Further, presently ongoing studies shall reveal i) the true complexity of these leaf-associated communities through cultivation-independent, next generation sequencing techniques, and ii) their potential as a source of biofungicidal agents. In this last point, the contribution of the emission of volatile organic compounds (VOCs) as a newly discovered type of bacterial weapon against fungal and oomycetal pathogens shall be quantified

Rethinking European integration history in light of capitalism: the case of the long 1970s

This introduction outlines the possibilities and perspectives of an intertwining between European integration history and the history of capitalism. Although debates on capitalism have been making a comeback since the 2008 crisis, to date the concept of capitalism remains almost completely avoided by historians of European integration. This introduction thus conceptualizes ‘capitalism’ as a useful analytical tool that should be used by historians of European integration and proposes three major approaches for them to do so: first, by bringing the question of social conflict, integral to the concept of capitalism, into European integration history; second, by better conceptualizing the link between European governance, Europeanization and the globalization of capitalism; and thirdly by investigating the economic, political and ideological models or doctrines that underlie European cooperation, integration, policies and institutions. Finally, the introduction addresses the question of the analytical benefits of an encounter between capitalism and European integration history, focusing on the case of the 1970s. This allows us to qualify the idea of a clear-cut rupture, and better highlight how the shift of these years resulted from a complex bargaining that took place in part at the European level

Building a European Identity: France, the United States, and the Oil Shock, 1973-74

The Arab-Israeli war of 1973, the first oil price shock, and France’s transition from Gaullist to centrist rule in 1974 coincided with the United States’ attempt to redefine transatlantic relations. As the author argues, this was an important moment in which the French political elite responded with an unprecedented effort to construct an internationally influential and internally cohesive European entity. Based on extensive multi-archival research, this study combines analysis of French policy making with an inquiry into the evolution of political language, highlighting the significance of the new concept of a political European identity.-- Acknowledgements -- Acronyms and abbreviations -- Introduction -- Chapter 1. Meeting the American Challenge: France and the Year of Europe -- Chapter 2. Constructing a European Identity -- Chapter 3. War in the Middle East. The Europeanization of France’s Arab Policy -- Chapter 4. Kissinger, Jobert and the Oil Shock -- Chapter 5. From a European Common Voice Towards Atlanticism? -- Chapter 6. Building a Political Europe in a Changed International Context: Giscard and the Twin Summits of Paris and Martinique -- Conclusions -- Bibliograph

Imagining European Identity: French Elites and the American Challenge in the Pompidou-Nixon Era

Charles de Gaulle has cast a long shadow over French political history and history writing. In exploring the French response to the United States' 1973 'Year of Europe' initiative, this article challenges the dominant scholarly paradigm, which emphasises continuity between the 19605 and the 1970s. Drawing on a wide range of French and US archives, it demonstrates that renewed concerns about US power spurred the French elites both to reappraise the value of collective European action in foreign policy and to foster a pioneering concept: a politically anchored as opposed to a geographically circumscribed 'European identity'

Volatile organic compounds of barley roots : belowground communication ?

Cette présentation résume les avancées du projet Rhizovol après une année de travaux de recherche.Projet Rhizovo

Fagopyrum esculentum Alters Its Root Exudation after Amaranthus retroflexus Recognition and Suppresses Weed Growth

Weed control by crops through growth suppressive root exudates is a promising alternative to herbicides. Buckwheat (Fagopyrum esculentum) is known for its weed suppression and redroot pigweed (Amaranthus retroflexus) control is probably partly due to allelopathic root exudates. This work studies whether other weeds are also suppressed by buckwheat and if the presence of weeds is necessary to induce growth repression. Buckwheat and different weeds were co-cultivated in soil, separating roots by a mesh allowing to study effects due to diffusion. Buckwheat suppressed growth of pigweed, goosefoot and barnyard grass by 53, 42, and 77% respectively without physical root interactions, probably through allelopathic compounds. Root exudates were obtained from sand cultures of buckwheat (BK), pigweed (P), and a buckwheat/pigweed mixed culture (BK-P). BK-P root exudates inhibited pigweed root growth by 49%. Characterization of root exudates by UHPLC-HRMS and principal component analysis revealed that BK and BK-P had a different metabolic profile suggesting that buckwheat changes its root exudation in the presence of pigweed indicating heterospecific recognition. Among the 15 different markers, which were more abundant in BK-P, tryptophan was identified and four others were tentatively identified. Our findings might contribute to the selection of crops with weed suppressive effects