AUTHOR=Pivato Barbara , Semblat Amélie , Guégan Thibault , Jacquiod Samuel , Martin Juliette , Deau Florence , Moutier Nathalie , Lecomte Christophe , Burstin Judith , Lemanceau Philippe 

TITLE=Rhizosphere Bacterial Networks, but Not Diversity, Are Impacted by Pea-Wheat Intercropping

JOURNAL=Frontiers in Microbiology

VOLUME=Volume 12 - 2021

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.674556

DOI=10.3389/fmicb.2021.674556

ISSN=1664-302X

ABSTRACT=Plant-plant associations, notably cereal-legume intercropping (IC), have been proposed in agroecology to better value resources and thus reduce the use of chemical inputs in agriculture. Wheat-pea IC allows to decreasing the use of nitrogen fertilization through ecological processes such as niche complementarity and facilitation. Rhizosphere microbial communities may account for these processes, since they play a major role in biogeochemical cycles and impact plant nutrition. Still, knowledge on the effect of IC on the rhizosphere microbiota remains scarce. Especially, it is an open question whether rhizosphere microbial communities in cereal-legume intercropping are the sum or not of the microbiota of each plant species cultivated in sole cropping (SC).
In the present study, we assessed the impact of wheat and pea in IC on the diversity and structure of their respective rhizosphere microbiota. For this purpose, several cultivars of wheat and pea were cultivated in SC and IC. Roots of wheat and pea were collected separately in IC for microbiota analyses to allow deciphering the effect of IC on the bacterial community of each plant species/cultivar tested.
Our data confirmed the well-known specificity of the rhizosphere effect and further stress the differentiation of bacterial communities between pea genotypes (Hr and hr). As regards the IC effect, diversity and structure of the rhizosphere microbiota were comparable to SC. Thus, a specific co-occurrence pattern in each crop rhizosphere due to IC was revealed through network analysis. Bacterial co-occurrence network of wheat rhizosphere in IC was dominated by OTUs belonging to Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria. We also evidenced a common network simultaneously found in both rhizosphere under IC, indicative of the interaction between the crops, dominated by Acidobacteria, Alphaproteobacteria and Bacteroidetes, and three OTUs belonging to Acidobacteria, Betaproteobacteria and Chloroflexi were identified as keystone taxa.
These findings indicate more complex rhizosphere bacterial networks in IC. Possible implications of these conclusions are discussed in relation with the functioning of rhizosphere microbiota in IC accounting for the beneficial effects of IC.