Alain Trouvelot

Bio: Alain Trouvelot is an academic researcher from Institut national de la recherche agronomique. The author has contributed to research in topics: Sativum & Pisum. The author has an hindex of 1, co-authored 1 publications receiving 326 citations.

Plant recognition of symbiotic bacteria requires two LysM receptor-like kinases

Abstract: Although most higher plants establish a symbiosis with arbuscular mycorrhizal fungi, symbiotic nitrogen fixation with rhizobia is a salient feature of legumes. Despite this host range difference, mycorrhizal and rhizobial invasion shares a common plant-specified genetic programme controlling the early host interaction. One feature distinguishing legumes is their ability to perceive rhizobial-specific signal molecules. We describe here two LysM-type serine/threonine receptor kinase genes, NFR1 and NFR5, enabling the model legume Lotus japonicus to recognize its bacterial microsymbiont Mesorhizobium loti. The extracellular domains of the two transmembrane kinases resemble LysM domains of peptidoglycan- and chitin-binding proteins, suggesting that they may be involved directly in perception of the rhizobial lipochitin-oligosaccharide signal. We show that NFR1 and NFR5 are required for the earliest physiological and cellular responses to this lipochitin-oligosaccharide signal, and demonstrate their role in the mechanism establishing susceptibility of the legume root for bacterial infection.

A plant receptor-like kinase required for both bacterial and fungal symbiosis

Abstract: Most higher plant species can enter a root symbiosis with arbuscular mycorrhizal fungi, in which plant carbon is traded for fungal phosphate. This is an ancient symbiosis, which has been detected in fossils of early land plants. In contrast, the nitrogen-fixing root nodule symbioses of plants with bacteria evolved more recently, and are phylogenetically restricted to the rosid I clade of plants. Both symbioses rely on partially overlapping genetic programmes. We have identified the molecular basis for this convergence by cloning orthologous SYMRK ('symbiosis receptor-like kinase') genes from Lotus and pea, which are required for both fungal and bacterial recognition. SYMRK is predicted to have a signal peptide, an extracellular domain comprising leucine-rich repeats, a transmembrane and an intracellular protein kinase domain. Lotus SYMRK is required for a symbiotic signal transduction pathway leading from the perception of microbial signal molecules to rapid symbiosis-related gene activation. The perception of symbiotic fungi and bacteria is mediated by at least one common signalling component, which could have been recruited during the evolution of root nodule symbioses from the already existing arbuscular mycorrhiza symbiosis.

Mycorrhizas in Natural Ecosystems

Abstract: Publisher Summary This chapter discusses the ecological implications of mycorrhizal associations in natural ecosystems and the role of soil or environmental factors, mycorrhizal fungus characteristics or host plant properties. Mycorrhizal associations are regulated by features of the host plant and mycorrhizal fungus, as well as by soil conditions and environmental factors. Factors which can influence the occurrence and effectiveness of mycorrhizal associations include (1) root properties (2) edaphic or climatic factors (3) soil organisms, (4) soil disturbance, and (5) host-fungus compatibility. Several other complex ecological topics also discussed in the chapter include (1) mycorrhizal phenology , (2) factors responsible for varying degrees of mycorrhizal dependency in host plants, (3) the role of mycorrhizal hyphae in soil (4) nutrient competition involving mycorrhizal and non-mycorrhizal plants, and (5) mycorrhizal interactions involving pollution and other stresses, the rhizosphere, soil properties and allelopathy. Finally, the chapter also discusses the population ecology of mycorrhizal fungi and the influence of their associations on plant population ecology.

Signaling in the arbuscular mycorrhizal symbiosis

Abstract: Many microorganisms form symbioses with plants that range, on a continuous scale, from parasitic to mutualistic. Among these, the most widespread mutualistic symbiosis is the arbuscular mycorrhiza, formed between arbuscular mycorrhizal (AM) fungi and vascular flowering plants. These associations occur in terrestrial ecosystems throughout the world and have a global impact on plant phosphorus nutrition. The arbuscular mycorrhiza is an endosymbiosis in which the fungus inhabits the root cortical cells and obtains carbon provided by the plant while it transfers mineral nutrients from the soil to the cortical cells. Development of the symbiosis involves the differentiation of both symbionts to create novel symbiotic interfaces within the root cells. The aim of this review is to explore the current understanding of the signals and signaling pathways used by the symbionts for the development of the AM symbiosis. Although the signal molecules used for initial communication are not yet known, recent studi...

A putative Ca2+ and calmodulin-dependent protein kinase required for bacterial and fungal symbioses.

Abstract: Legumes can enter into symbiotic relationships with both nitrogen-fixing bacteria (rhizobia) and mycorrhizal fungi. Nodulation by rhizobia results from a signal transduction pathway induced in legume roots by rhizobial Nod factors. DMI3, a Medicago truncatula gene that acts immediately downstream of calcium spiking in this signaling pathway and is required for both nodulation and mycorrhizal infection, has high sequence similarity to genes encoding calcium and calmodulin-dependent protein kinases (CCaMKs). This indicates that calcium spiking is likely an essential component of the signaling cascade leading to nodule development and mycorrhizal infection, and sheds light on the biological role of plant CCaMKs.