Relationship between bacterial communities via UniFrac distances.

<p>(A): Hierarchical clustering of weighted pairwise UniFrac distances between microbial communities of the different samples based on their distribution of bacterial 16S rDNA gene sequences (v4-v5 region). (B): Principal coordinates plot (PCoA) generated using weighted UniFrac distances between the bacterial communities for each sample analysed. Different shapes represent species: inverted triangle = <i>D</i>. <i>radicum</i>, upright triangle = <i>T</i>. <i>rapae</i>, square = <i>A</i>. <i>bipustulata</i>, circle = <i>A</i>. <i>bilineata</i>. Colours represent sampling zones: white = western, grey = eastern, black = central (for <i>A</i>. <i>bilineata</i> only). Two technical replicates are used, but with the exception of eastern <i>D</i>. <i>radicum</i> they are so similar as to appear superposed on the graph.</p

Maximum likelihood tree of Wolbachia spp. obtained from 16S V4-V5, 16S wspec and fbpA fragments.

<p>The Wolbachia hosts and the supergroup of the Wolbachia (when available) are indicated. Bootstrap values are given for each branch. Scaling is expressed in the proportion of substituted bases per site.</p

Details about samples: <i>Species</i>, <i>sites sampled</i>, <i>corresponding area</i>, <i>number of generations reared in the laboratory and</i> number of individuals used in 454 sequencing.

<p>Details about samples: <i>Species</i>, <i>sites sampled</i>, <i>corresponding area</i>, <i>number of generations reared in the laboratory and</i> number of individuals used in 454 sequencing.</p

Maximum likelihood tree of Spiroplasma spp. obtained from the 16S V4-V5 fragment.

<p>Information is presented in the following order: bacteria name; host name in brackets (when available); OTU number for <i>Delia radicum</i>, <i>Aleochara bilineata</i>, <i>Aleochara bipustulata</i> and <i>Trybliographa rapae</i>. Bootstrap values (≥60; black) are given for each branch. Scaling is expressed in the proportion of substituted bases per site. Roman letters indicate serological groups.</p

Abundance of bacterial taxa from each samples: Abundance of dominant species in our dataset based on 97% similarity OTU assignments.

<p>‘Western’, ‘central’ and ‘eastern’ populations refer respectively to Finistère, Côtes d’Armor and Ille & Vilaine regions of Brittany. Numbers indicate the number of reads associated to each genus. Known heritable symbionts are marked by an asterisk (results of both PCR replicates are pooled).</p

Distribution of OTUs (97% similarity) among the four host species.

<p>Distribution of OTUs (97% similarity) among the four host species.</p

Bacterial diversity indexes: Richness and diversity indexes associated with each sample and replicate.

<p>‘Western’, ‘central’ and ‘eastern’ populations refer respectively to the Finistère, Côtes d’Armor and Ille & Vilaine regions of Brittany. Coverage = estimated percentage of (Chao 1) richness identified.</p

Maximum likelihood tree of Rickettsia spp. obtained from the 16S V4-V5 fragment.

<p>Information is presented in the following order: bacteria name; host name in brackets (when available); OTU number for <i>Aleochara bilineata</i> and <i>Trybliographa rapae</i>. Bootstrap values (≥60; black) are given for each branch. Scaling is expressed in the proportion of substituted bases per site.</p

Image_2_Influence of Belowground Herbivory on the Dynamics of Root and Rhizosphere Microbial Communities.PDF

<p>Recent studies are unraveling the impact of microorganisms from the roots and rhizosphere on interactions between plants and herbivorous insects and are gradually changing our perception of the microorganisms' capacity to affect plant defenses, but the reverse effect has seldom been investigated. Our study aimed at determining how plant herbivory influences the dynamics of root and rhizosphere microbial community assemblages and whether potential changes in root metabolites and chemical elements produced during herbivory can be related to microbial community diversity. We conducted our study on oilseed rape (Brassica napus) and its major belowground herbivore, the cabbage root fly (Delia radicum). We further assessed the influence of initial soil microbial diversity on these interactions. Different microbial diversities based on a common soil matrix were obtained through a removal-recolonization method. Root and rhizosphere sampling targeted different stages of the herbivore development corresponding to different perturbation intensities. Root bacterial communities were more affected by herbivory than some rhizosphere bacterial phyla and fungal communities, which seemed more resistant to this perturbation. Root herbivory enhanced the phylum of γ-Proteobacteria in the roots and rhizosphere, as well as the phylum of Firmicutes in the rhizosphere. Herbivory tended to decrease most root amino acids and sugars, and it increased trehalose, indolyl glucosinolates, and sulfur. Higher abundances of four bacterial genera (Bacillus, Paenibacillus, Pseudomonas, and Stenotrophomonas) were associated following herbivory to the increase of trehalose and some sulfur-containing compounds. Further research would help to identify the biological functions of the microbial genera impacted by plant infestation and their potential implications in plant defense.</p

Table_5_Influence of Belowground Herbivory on the Dynamics of Root and Rhizosphere Microbial Communities.xlsx

<p>Recent studies are unraveling the impact of microorganisms from the roots and rhizosphere on interactions between plants and herbivorous insects and are gradually changing our perception of the microorganisms' capacity to affect plant defenses, but the reverse effect has seldom been investigated. Our study aimed at determining how plant herbivory influences the dynamics of root and rhizosphere microbial community assemblages and whether potential changes in root metabolites and chemical elements produced during herbivory can be related to microbial community diversity. We conducted our study on oilseed rape (Brassica napus) and its major belowground herbivore, the cabbage root fly (Delia radicum). We further assessed the influence of initial soil microbial diversity on these interactions. Different microbial diversities based on a common soil matrix were obtained through a removal-recolonization method. Root and rhizosphere sampling targeted different stages of the herbivore development corresponding to different perturbation intensities. Root bacterial communities were more affected by herbivory than some rhizosphere bacterial phyla and fungal communities, which seemed more resistant to this perturbation. Root herbivory enhanced the phylum of γ-Proteobacteria in the roots and rhizosphere, as well as the phylum of Firmicutes in the rhizosphere. Herbivory tended to decrease most root amino acids and sugars, and it increased trehalose, indolyl glucosinolates, and sulfur. Higher abundances of four bacterial genera (Bacillus, Paenibacillus, Pseudomonas, and Stenotrophomonas) were associated following herbivory to the increase of trehalose and some sulfur-containing compounds. Further research would help to identify the biological functions of the microbial genera impacted by plant infestation and their potential implications in plant defense.</p