ena-STUDY-INRA (INRA Rennes)-27-02-2018-12:51:49:271-706
Root Herbivory Shapes The Dynamic Of Oilseed Root And Rhizosphere Microbial Communities Through Chemical Changes
Interactions between plants and herbivorous insects are known to influence the evolution of plant defenses. Recent studies are unravelling the impact of microorganisms from the rhizosphere on such interactions and are gradually changing our perception, but the reverse effect has seldom been investigated. Herbivore attacks on plants could represent important perturbations for belowground communities. Our study aimed at determining how plant herbivory influences resistance and resilience of root and rhizosphere microbial community assemblages and whether potential changes in root metabolites and elemental compounds during herbivory can explain microbial community dynamics. We further questioned the influence of initial soil microbial diversity on these interactions. We conducted our study on a crop plant, oilseed rape (Brassica napus) and one of its major belowground pest, the cabbage root fly (Delia radicum). Soils of different initial microbial diversity were obtained through a removal-recolonization method. Root and rhizosphere sampling targeted different stages of the herbivore development: i) the hatching stage which corresponds to the initiation of herbivory, ii) the third larval instar which corresponds to the peak of herbivory and iii) adult emergence which corresponds to the end of herbivory. Bacterial communities were more affected by herbivory than fungi communities, which appeared very variable. Herbivory was associated to an increase of ?-Proteobacteria and of 5 bacterial dominant genera belonging to this phylum and Firmicutes. Root communities were more resilient than rhizosphere communities. This resilience was partly visible at the root metabolite and nutrient level, which reached back a more stable state at the end of herbivory. But herbivory also induced an increase of sulfur-containing compounds, as well as a couple amino acids and sugars. Three bacterial genera were positively correlated to most metabolites and negatively to nutrients. Further researches would help to identify the biological function of the microbial genera impacted by plant infestation and their potential implication in the plant defense.
Interactions between plants and herbivorous insects are known to influence the evolution of plant defenses. Recent studies are unravelling the impact of microorganisms from the rhizosphere on such interactions and are gradually changing our perception, but the reverse effect has seldom been investigated. Herbivore attacks on plants could represent important perturbations for belowground communities. Our study aimed at determining how plant herbivory influences resistance and resilience of root and rhizosphere microbial community assemblages and whether potential changes in root metabolites and elemental compounds during herbivory can explain microbial community dynamics. We further questioned the influence of initial soil microbial diversity on these interactions. We conducted our study on a crop plant, oilseed rape (Brassica napus) and one of its major belowground pest, the cabbage root fly (Delia radicum). Soils of different initial microbial diversity were obtained through a removal-recolonization method. Root and rhizosphere sampling targeted different stages of the herbivore development: i) the hatching stage which corresponds to the initiation of herbivory, ii) the third larval instar which corresponds to the peak of herbivory and iii) adult emergence which corresponds to the end of herbivory. Bacterial communities were more affected by herbivory than fungi communities, which appeared very variable. Herbivory was associated to an increase of ?-Proteobacteria and of 5 bacterial dominant genera belonging to this phylum and Firmicutes. Root communities were more resilient than rhizosphere communities. This resilience was partly visible at the root metabolite and nutrient level, which reached back a more stable state at the end of herbivory. But herbivory also induced an increase of sulfur-containing compounds, as well as a couple amino acids and sugars. Three bacterial genera were positively correlated to most metabolites and negatively to nutrients. Further researches would help to identify the biological function of the microbial genera impacted by plant infestation and their potential implication in the plant defense.