A new conceptual framework shows that plant genotype and soil nitrogen availability modify both plant nutritional strategies and diversity of their associated rhizosphere microbiome

International audienceIn the context of sustainable agriculture, it is desirable to lower the input of mineral fertilizers. Therefore, we need to select ‘new’ genotypes that are both adapted to ‘low fertilizer inputs’ and more efficient in nutrient use. A better understanding of plant-microbe interactions under low input of fertilizers is now needed. Nevertheless, in microbial ecology, conceptual frameworks or models are used to analyse plant-microbe interactions but plant phenotype is currently viewed as a “black box”. We developed a new conceptual framework to study plant-microbe interactions using a multidisciplinary approach combining Microbial Ecology and Plant Ecophysiology.The links among plant genotype, soil nitrogen availability and the plant associated rhizosphere microbiome were assessed at both structural and functional level. On the one hand, the influence of both Medicago truncatula genotype and soil nitrogen availability on the genetic structure of the soil microbiome was determined by DNA fingerprint and 454 pyrosequencing. On the other hand, the different nutritional strategies of the plant-microbe interactions were evaluated using an ecophysiological framework.We observed that nitrogen availability affected rhizosphere bacterial communities only in presence of the plant. Furthermore, we demonstrated the existence of a strong Medicago truncatula genotype x nitrogen availability effect on the rhizosphere bacterial communities. Finally, the nutritional strategies of the plant varied greatly in response to a modification of nitrogen availability. Three contrasted structural and functional adaptive responses of plant-microbe interactions to nitrogen availability were thus identified.With recent developments in statistics and high throughput genotyping, this new conceptual framework is now used in a genome-wide association studies (GWAS) to identify plant genetic determinants that may be linked to the selection of more beneficial microbiome for plant under low input of fertilizers

Soil Nitrogen Availability and Plant Genotype Modify the Nutrition Strategies of M. truncatula and the Associated Rhizosphere Microbial Communities

International audiencePlant and soil types are usually considered as the two main drivers of the rhizosphere microbial communities. The aim of this work was to study the effect of both N availability and plant genotype on the plant associated rhizosphere microbial communities, in relation to the nutritional strategies of the plant-microbe interactions, for six contrasted Medicago truncatula genotypes. The plants were provided with two different nutrient solutions varying in their nitrate concentrations (0 mM and 10 mM). First, the influence of both nitrogen availability and Medicago truncatula genotype on the genetic structure of the soil bacterial and fungal communities was determined by DNA fingerprint using Automated Ribosomal Intergenic Spacer Analysis (ARISA). Secondly, the different nutritional strategies of the plant-microbe interactions were evaluated using an ecophysiological framework. We observed that nitrogen availability affected rhizosphere bacterial communities only in presence of the plant. Furthermore, we showed that the influence of nitrogen availability on rhizosphere bacterial communities was dependent on the different genotypes of Medicago truncatula. Finally, the nutritional strategies of the plant varied greatly in response to a modification of nitrogen availability. A new conceptual framework was thus developed to study plant-microbe interactions. This framework led to the identification of three contrasted structural and functional adaptive responses of plant-microbe interactions to nitrogen availability

Sublethal dose effects of a neonicotinoid insecticide, clothianidin, on sex pheromone responses in the black cutworm moth

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ST1-5_and_SF_1-2 – Supplemental material for Efficacy of Sensory Interventions on School Participation of Children With Sensory Disorders: A Systematic Review

Supplemental material, ST1-5_and_SF_1-2 for Efficacy of Sensory Interventions on School Participation of Children With Sensory Disorders: A Systematic Review by Béatrice Ouellet, Emmanuelle Carreau, Valérie Dion, Anouk Rouat, Elyse Tremblay and Julien I. A. Voisin in American Journal of Lifestyle Medicine</p

Contrasted symbiotic microbial infection among different <i>Medicago truncatula</i> genotypes and soil N availability.

<p><b>a.</b> Intensity of nodulation of the six <i>Medicago truncatula</i> genotypes studied under contrasted soil N availability (0 mM and 10 mM N). The intensity of nodulation was evaluated using a visual scale <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047096#pone.0047096-Moreau3" target="_blank">[25]</a> which includes five scores: 0 (absence of nodules), 1 (only some white small size nodules), 2 (both white and pink small size nodules), 3 (mainly pink larger size nodules), and 4 (many pink large size nodules). <b>b.</b> Intensity of colonisation of the root cortex (M%) under contrasted soil N availability (0 mM and 10 mM N) for the group of genotype DZA315-16/DZA315-26 and the other genotypes.</p

Summary of statistical analysis (2- factor ANOVA) comparing the effect of genotype and N availability on the symbiotic microbial infection.

<p>Significance of ANOVA: ns, ** and *** indicate not significant and significant levels of 0.01 and 0.001 respectively.</p

Contrasted adaptive responses of different <i>Medicago truncatula</i> genotypes to nitrogen availability.

<p>Contrasted adaptive responses of different <i>Medicago truncatula</i> groups of genotypes to nitrogen availability was assessed using a conceptual framework of plant functioning <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0047096#pone.0047096-Moreau1" target="_blank">[15]</a> extended to plant-microbe interactions. Group 1 includes DZA315-16 and DZA315-26; Group 2 includes F83005-5 and SA028064; Group 3 includes Jemalong-A17, Jemalong-J6. State integrative variables are in grey boxes, efficiency variables are in white boxes and non-measured putative effects are in dotted boxes. The red and blue arrows represent respectively a significant increase and decrease, from low to high N availability.</p