Search results for "RELATION HOTE-PARASITE"
showing 8 items of 8 documents
Vigna mungo, V. radiata and V. unguiculata plants sampled in different agronomical-ecological-climatic regions of India are nodulated by Bradyrhizobi…
2009
International audience; Vigna mungo, Vigna radiata and Vigna unguiculata are important legume crops cultivated in India, but little is known about the genetic resources in native rhizobia that nodulate these species. To identify these bacteria, a core collection of 76 slow-growing isolates was built from root nodules of V. mungo, V. radiata and V. unguiculata plants grown at different sites within three agro-ecological-climatic regions of India. The genetic diversity of the bacterial collection was assessed by restriction fragment length polymorphism (RFLP) analysis of PCR-amplified DNA fragments of the 16S–23S rDNA intergenic spacer (IGS) region, and the symbiotic genes nifH and nodC. One …
Le syndrome des basses richesses de la betterave sucrière en Bourgogne, un modèle de maladies infectieuses émergentes - Bilan des recherches 1997-2007
2008
National audience; Une maladie inconnue de la betterave sucrière est apparue en Côte d'Or au début des années 1990 et a gagné le reste du bassin sucrier du Centre-est (Bourgogne et Jura). Les programmes d'étude financés par la filière betterave-sucre et Conseil régional de Bourgogne de 1997 à 2007, ont permis d'en élucider entièrement l'étiologie et la transmission, de développer des méthodes de diagnostic moléculaire, et de parvenir à une compréhension globale de son épidémiologie. Les méthodes de lutte directes et agronomiques préconisées ont montré leur efficacité pour limiter les pertes de rendement en sucre associées à cette maladie. Par ailleurs, la biologie de bactéries pathogènes ha…
Interactions between a mycorrhiza helper bacterium and arbuscular mycorrhizas
2009
Pseudomonas fluorescens C7R12 was shown to promote arbuscular mycorrhization and to act as a ‘Mycorrhiza Helper Bacteria’ (MHB). The complex interactions between this model strain, Arbuscular Mycorrhizal (AM) fungi and host-plants were analysed by assessing the specificity of these interactions and by characterizing bacterial cell organization on mycorrhizal roots. Evaluation of the interaction specificity relied on the comparison of the bacterial effect on (i) the in vitro saprophytic growth of Glomus mosseae and Gigasopora rosea and (ii) the root colonization of two different plant species (Medicago truncatula and Lycopersicon esculentum) by the two AM fungal species. Characterization of …
Host kairomone learning and foraging success in an egg parasitoid: a simulation model
2009
Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) is an egg parasitoid that recognises chemical residues left by its host the green stink bug Nezara viridula (L.) (Heteroptera: Pentatomidae) as kairomone signals, enabling it to find egg masses in which to lay eggs. 2. Kairomones are usually present as patches deposited by N. viridula females, and recent results (Peri et al. , Journal of Experimental Biology , 209 , 3629 - 3635, 2006) indicated that females of T. basalis are able to learn the features of their foraging environment and to adjust accordingly the amount of time spent on the patches of kairomones they are visiting, depending on whether or not host eggs are found. 3. In o…
Field evidence of host size-dependent parasitism in two manipulative parasites.
2007
5 pages; International audience; The distribution of parasites within host natural populations has often been found to be host age-dependent. Host mortality induced by parasites is the commonest hypothesis proposed for explaining this pattern. Despite its potential importance in ecology, the parasitism intensity in relation with the host age has rarely been studied in the field. The 2 manipulative acanthocephalans, Polymorphus minutus and Pomphorhynchus laevis, use the amphipod Gammarus pulex as an intermediate host, and their infection intensity and incidence among G. pulex populations were examined by analyzing 2 large samples of hosts collected in eastern France. Both parasites had low p…
Denitrification in pathogenic bacteria : for better or worst ?
2005
A large variety of physiological and taxonomic groups have the ability to use nitrogen oxides as alternative electron acceptors. Brucella spp. is an alpha-proteobacteriaceae that induces a persistent disease in some mammals. Recent work has revealed that a denitrifying gene cluster is important in the interaction of Brucella neotomoae with its host.
Are grapevine stomata involved in the elicitor-induced protection against downy mildew?
2009
Stomata, natural pores bordered by guard cells, regulate transpiration and gas exchanges between plant leaves and the atmosphere. These natural openings also constitute a way of penetration for microorganisms. In plants, the perception of potentially pathogenic microorganisms or elicitors of defense reactions induces a cascade of events, including H2O2 production, that allows the activation of defense genes, leading to defense reactions. Similar signaling events occur in guard cells in response to the perception of abscisic acid (ABA), leading to stomatal closure. Moreover, few elicitors were reported to induce stomatal closure in Arabidopsis and Vicia faba leaves. Because responses to ABA…
Emerging mutualisms: fungal endophytes and their relationships with mycorrhizal fungi
2011
National audience; De nombreuses maladies émergentes apparaissent qui sont dues à des champignons, aussi bien chez les plantes, les animaux que chez l’homme. Il est donc important de comprendre les mécanismes à l’origine de ces maladies, et la biologie évolutive fournit un cadre théorique indispensable, en particulier pour comprendre l’adaptation des pathogènes aux nouveaux environnements ou aux nouveaux hôtes.