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Sara Correa Garcia

INRS Institut Armand Frappier
Functional convergence in the rhizosphere of poplars growing in various contaminated soils

Sara Correa-García, Karelle Rhault, Armand Séguin, Etienne Yergeau

Rhizodegradation is a promising cleanup technology where microorganisms degrade soil contaminants in the rhizosphere. A symbiotic relationship is expected to occur between plant roots and soil microorganisms in contaminated soils. However, little is known about the nature of this plant-microbe relationship, and how this varies with soil type/initial microbiota. Therefore, the aim of this study was to test the effects of different soil types on the development and the taxonomical and functional microbial communities of balsam poplars (Populus balsamifera) under phenanthrene contamination. We hypothesized that, regardless of the original soil type and microbial community composition, poplar trees under contaminated conditions will select for microorganisms carrying out similar functions associated with plant growth promotion and contaminant degradation. A 6L-pot full-factorial experiment with three factors has been carried out, each factor having two levels: soil type and initial microbial community: agricultural / forest soil; contamination status: 50mg·kg-1 phenanthrene (contaminated) / 0mg·kg-1 (non-contaminated); trees: planted / not planted. Twelve replicates per treatment were organized in 4 blocks containing 3 replicates each. After two months of growth, plant shoots, rhizosphere, and bulk soil were sampled for metagenomic analysis, plant morphological traits (biomass and plant size) and phenanthrene levels. Results highlighting key functions and taxa selected by poplars when facing contaminant stress, regardless of initial microbial community and soil type will be presented. This experiment will also inform us if certain community types or functional gene variants are more efficient than others in promoting poplar growth and phenanthrene degradation.