Search results for "Nitrogen"

Nitrogen cycling microbial communities: from diversity to interactions and functions

2019

Soil microorganisms form one of the largest biodiversity reservoirs on earth. They also play essential roles in ecosystem functions such as biogeochemical cycling. However, the importance of microbial community diversity and composition for ecosystem functioning is still debated. A sound understanding of the ecological processes governing the assembly of these communities in the environment is also missing. In this talk, I will give examples of how we addressed these knowledge gaps using nitrogen cycling microorganisms as model functional guilds. Nitrogen is the most limiting nutrient for crop production in agriculture. The nitrogen cycle is also one which was pushed by human activities out…

Traking nitrate reducers and denitrifiers in the environment

2005

The ability to respire nitrate when oxygen is limited has been described in taxonomically diverse microorganisms including members of the alpha-, beta-, gamma- and epsilon-proteobacteria, high and low GC Gram-positive bacteria and even Archaea. Respiratory nitrate reduction is the first step of the denitrification pathway, which is important since it is the main biological process responsible for the return of fixed nitrogen to the atmosphere, thus completing the nitrogen cycle. During the last decade, considerable knowledge has been accumulated on the biochemistry and genetics of the nitrate reductases. In this paper, we summarize the recent progress in molecular approaches for studying th…

Growth and development of Ambrosia artemisiifolia L. under different trophic conditions

2014

Ambrosia artemisiifolia L. (common ragweed) is an annual weed regarded as an invasive plant in France. This species can be found in a large range of soil types with regard to texture, pH or nutrient contents. Furthermore, its tolerance to different forms of stress increases its spread potential. This work was undertaken to evaluate the development and growth of common ragweed under different trophic conditions in a common garden. Three cohorts of 15 plants per treatments were sown in spring 2013 and the effects of nitrogen and irrigation were compared on each sowing dates. During the first weeks, vegetative appearance is strongly linked with the sum of temperature. For the first cohort, the…

Crosstalks between soil microbial communities and a nitrogen fixing legume species (medicago truncatula) during its Vegetative Stage

2010

International audience

Linking microbial diversity and ecosystem functioning: The nitrogen cycle example

2014

Microbial communities have a central role in ecosystem processes by driving the Earth’s biogeochemical cycles. However, the importance of microbial diversity for ecosystem functioning is still debated. While functional trait-based approaches are commonly used for at least two decades in microbiology, most microbial diversity studies are still carried out with the rRNA genes. This talk will show how metagenomic approaches targeting microbial guilds involved in nitrogen cycling can help bridging microbial community ecology and ecosystem processes in terrestrial environments.

Disentangling the complexity and diversity of crosstalks between S and other mineral nutrients in cultivated plants

2018

International audience

Genetic diversity for partner choice in a core collection of pea accessions inoculated by a mix of five Rhizobium leguminosarum bv. viciae genotypes

2013

National audience

Variabilité génétique pour la morphologie du système racinaire du pois. Impact sur la nutrition azotée

2012

Genetic diversity of nodulated root structure and nitrogen nutrition in a core collection of pea

2013

Pea (Pisum sativum) is the third most important grain legume worldwide, and the increasing demand for protein-rich raw material for animal feed or human nutrition has led to a greater interest in this crop as a protein source. Moreover, legumes do not need nitrogen (N) fertilizers, thanks to their natural ability to use, as main N resource, the atmospheric N2 from symbiosis in nodules with Rhizobiaceae spp. However, N nutrition can still be a limiting factor of yield and seed quality in legumes because nodules are very sensitive to their local environment, in particular to nitrate, and root systems of N2 fixing legumes are poorly developed, which makes them unable to explore a large soil vo…

Interaction between Medicago truncatula and the pathogenic oomycete Aphanomyces euteiches: effects of nitrogen nutrition and plant genotype

2015

Plants are under the constant threat of microbial pathogens. To defend themselves, plants have developed immune responses (including for example synthesis of antimicrobial secondary metabolites, production of PR proteins or reinforcement of cell wall) that can lead to resistance. However, these plant defense responses are costly and lead plants to continuously face a dilemma regarding the partitioning of their available resources. In order to better understand relationships between plant nutrition and defense, we analyzed the impact of nitrogen (N) nutrition on the capacity of different M. truncatula genotypes to resist against A. euteiches, the causal agent of legume root rot disease. N st…