Plant hosts control microbial denitrification activity

Wafa Achouak (1, 2) , Danis Abrouk (3) , Julien Guyonnet (3) , ​mohamed Barakat (1, 2) , Philippe Ortet (1, 2) , Laurent Simon (4) , Catherine Lerondelle (3) , Thierry Heulin (1, 2) , Feth El Zahar Haichar (3)

1 BIAM - Institut de Biosciences et Biotechnologies d'Aix-Marseille (ex-IBEB)
2 LEMIRE - Laboratoire d'Ecologie Microbienne de la Rhizosphère et d'Environnements Extrêmes
3 LEM - Laboratoire d'Ecologie Microbienne - UMR 5557
4 LEHNA - Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés

In the rhizosphere, complex and dynamic interactions occur between plants and microbial networks that are primarily mediated by root exudation. Plants exude various metabolites that may influence the rhizosphere microbiota. However, few studies have sought to understand the role of root exudation in shaping the functional capacities of the microbiota. In this study, we aimed to determine the impact of plants on the diversity of active microbiota and their ability to denitrify via root exudates. For that purpose, we grew four plant species, Triticum aestivum, Brassica napus, Medicago truncatula and Arabidopsis thaliana separately in the same soil. We extracted RNA from the root-adhering soil and the root tissues, and we analysed the bacterial diversity by using 16S rRNA metabarcoding. We measured denitrification activity and denitrification gene expression (nirK and nirS) from each root-adhering soil sample and the root tissues using gas chromatography and quantitative PCR, respectively. We demonstrated that plant species shape denitrification activity and modulate the diversity of the active microbiota through root exudation. We observed a positive effect of T. aestivum and A. thaliana on denitrification activity and nirK gene expression on the root systems. Together, our results underscore the potential power of host plants in controlling microbial activities.

Mots clés: nitrogen uptake; root-adhering soil; rhizosphere; root; denitrification; active microbiota; root exudates

Domaines: Sciences du Vivant [q-bio]; Sciences de l'environnement

Wafa Achouak, Danis Abrouk, Julien Guyonnet, ​mohamed Barakat, Philippe Ortet, et al.. Plant hosts control microbial denitrification activity. FEMS Microbiology Ecology, 2019, 95 (3), pp.fiz021. ⟨10.1093/femsec/fiz021⟩. ⟨cea-02096084⟩