Plant-Microbe Interactions
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Rescooped by Audrey Kalil from Plants and Microbes
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Science: Nonlegumes Respond to Rhizobial Nod Factors by Suppressing the Innate Immune Response (2013)

Science: Nonlegumes Respond to Rhizobial Nod Factors by Suppressing the Innate Immune Response (2013) | Plant-Microbe Interactions | Scoop.it

Virtually since the discovery of nitrogen fixing Rhizobium-legume symbioses, researchers have dreamed of transferring this capability into nonlegume crop species (e.g., corn). It has been generally assumed that nonlegumes lack the ability to respond to the rhizobial lipo-chitin Nod factors, which are the essential signal molecules that trigger legume nodulation. However, our data indicate that Arabidopsis thaliana, as well as other nonlegume plants, do indeed recognize the rhizobial Nod factor via a mechanism that results in strong suppression of microbe-associated molecular pattern (MAMP)–triggered immunity. The mechanism of action leads to reduced levels of pattern recognition receptors on the plasma membrane involved in MAMP recognition.


Via Kamoun Lab @ TSL
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Rescooped by Audrey Kalil from Plant-Microbe Symbiosis
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The role of mycorrhizal associations in plant potassium nutrition

Potassium (K+) is one of the most abundant elements of soil composition but its very low availability limits plant growth and productivity of ecosystems. Because this cation participates in many biological processes, its constitutive uptake from soil solution is crucial for the plant cell machinery. Thus, the understanding of strategies responsible of K+ nutrition is a major issue in plant science. Mycorrhizal associations occurring between roots and hyphae of underground fungi improve hydro-mineral nutrition of the majority of terrestrial plants. The contribution of this mutualistic symbiosis to the enhancement of plant K+ nutrition is not well understood and poorly studied so far. This mini-review examines the current knowledge about the impact of both arbuscular mycorrhizal and ectomycorrhizal symbioses on the transfer of K+ from the soil to the plants. A model summarizing plant and fungal transport systems identified and hypothetically involved in K+ transport is proposed. In addition, some data related to benefits for plants provided by the improvement of K+ nutrition thanks to mycorrhizal symbioses are presented.


Via Kevin Garcia, Jean-Michel Ané
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Rescooped by Audrey Kalil from Plant-Microbe Symbiosis
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The responses of two pea genotypes to Nod factors (LCOs) treatment

The responses of two pea genotypes to treatment with Rhizobium Nod factors were analysed in a pot experiment with a completely randomised design. The first-order factor was pea cultivar: Milwa and Klif, and the second-order factor was seed soaking: control (distilled water), solution-containing Nod factors (LCOs) at a concentration of 10-12M·dm-3 water. Pea plants were harvested at the flowering (BBCH 60) and at fully ripe stage (BBCH 90). In both pea cultivars, the application of Rhizobium Nod factors improved plant growth and yield. Nod factors (LCOs) accelerated seed germination and contributed to significant differences in seedling emergence patterns between days 7 and 11 after seed sowing. Nod factor treatment increased the number and weight of root nodules, thus stimulating the growth of vegetative and reproductive organs in pea plants. Nod factors had the greatest influence on the dry matter yield of peas at the fruit development stage, which is marked by intensive plant growth. The increase in seed yield observed after the application of Rhizobium LCOs resulted from a higher number of pods and seeds per plant and improved grain plumpness. It was found that the number of root nodules was highly correlated with seed yield. Several differences in the responses of the analysed genotypes to Nod treatment were observed, most significant being a higher number of root nodules and improved yield of peas cv. Klif.


Via Jean-Michel Ané
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Rescooped by Audrey Kalil from Plant & Evolution
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Convergent Targeting of a Common Host Protein-Network by Pathogen Effectors from Three Kingdoms of Life

Convergent Targeting of a Common Host Protein-Network by Pathogen Effectors from Three Kingdoms of Life | Plant-Microbe Interactions | Scoop.it

Highlights

 

•Powdery mildew fungus G. orontii virulence effectors and their host-interactors identified•Integrated network map reveals interspecies effector convergence onto shared host proteins•Mutants of convergent effector-targeted host proteins display altered infection phenotypes•Host genes under balancing selection encode indirect targets of pathogen effectors

 

Summary

While conceptual principles governing plant immunity are becoming clear, its systems-level organization and the evolutionary dynamic of the host-pathogen interface are still obscure. We generated a systematic protein-protein interaction network of virulence effectors from the ascomycete pathogen Golovinomyces orontii and Arabidopsis thaliana host proteins. We combined this data set with corresponding data for the eubacterial pathogen Pseudomonas syringae and the oomycete pathogen Hyaloperonospora arabidopsidis. The resulting network identifies host proteins onto which intraspecies and interspecies pathogen effectors converge. Phenotyping of 124 Arabidopsis effector-interactor mutants revealed a correlation between intraspecies and interspecies convergence and several altered immune response phenotypes. Several effectors and the most heavily targeted host protein colocalized in subnuclear foci. Products of adaptively selected Arabidopsis genes are enriched for interactions with effector targets. Our data suggest the existence of a molecular host-pathogen interface that is conserved across Arabidopsis accessions, while evolutionary adaptation occurs in the immediate network neighborhood of effector targets.


Via Pierre-Marc Delaux
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Rescooped by Audrey Kalil from Plant-Microbe Symbiosis
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Lipochitooligosaccharide recognition: an ancient story

Lipochitooligosaccharide recognition: an ancient story | Plant-Microbe Interactions | Scoop.it
Chitin is the second most abundant polysaccharide in nature, found in crustacean shells, insect exoskeletons and fungal cell walls. The action of chitin and chitin derivatives on plants has become a very interesting story of late. Chitin is a β1-4-linked polymer of N-acetyl-d-glucosamine (GlcNAc). In this unmodified form, chitooligosaccharides (degree of polymerization (dp) = 6–8)) are strong inducers of plant innate immunity. By contrast, when these chitooligosaccharides are acylated (so-called lipochitooligosaccharides, LCOs) and further modified, they can act as Nod factors, the key signaling molecules that play an important role in the initiation of the legume–rhizobium symbiosis. In a similar form, these molecules can also act as Myc factors, the key signaling molecules involved in the arbuscular mycorrhizal (AM) symbiosis. It has been proposed that Nod factor perception might have evolved from the more ancient AM symbiosis. Increasing evidence now suggests that LCO perception might have evolved from plant innate immunity signaling. In this review, we will discuss the evolutionary origin of symbiotic LCO recognition.
Via Jean-Michel Ané
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Rescooped by Audrey Kalil from Rhizobium Research
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Evolution of the plant–microbe symbiotic ‘toolkit’

Evolution of the plant–microbe symbiotic ‘toolkit’ | Plant-Microbe Interactions | Scoop.it

Beneficial associations between plants and arbuscular mycorrhizal fungi play a major role in terrestrial environments and in the sustainability of agroecosystems. Proteins, microRNAs, and small molecules have been identified in model angiosperms as required for the establishment of arbuscular mycorrhizal associations and define a symbiotic ‘toolkit’ used for other interactions such as the rhizobia–legume symbiosis. Based on recent studies, we propose an evolutionary framework for this toolkit. Some components appeared recently in angiosperms, whereas others are highly conserved even in land plants unable to form arbuscular mycorrhizal associations. The exciting finding that some components pre-date the appearance of arbuscular mycorrhizal fungi suggests the existence of unknown roles for this toolkit and even the possibility of symbiotic associations in charophyte green algae.

 

Pierre-Marc Delaux, Nathalie Séjalon-Delmas, Guillaume Bécard, Jean-Michel Ané (2013).  Trends in Plant Sciences, In press. Available online 22 February 2013.


Via IvanOresnik
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