Plant Genotype Influences Physicochemical Properties of Substrate as Well as Bacterial and Fungal Assemblages in the Rhizosphere of Balsam Poplar

Abstract

Abandoned unrestored mines are an important environmental concern as they typically remain unvegetated for decades, exposing vast amounts of mine waste to erosion. Several factors limit the revegetation of these sites, including extreme abiotic and unfavorable biotic conditions. However, some pioneer tree species having high levels of genetic diversity, such as balsam poplar (Populus balsamifera), can naturally colonize these sites and initiate plant succession. This suggests that some tree genotypes are likely more suited for acclimation to the conditions of mine wastes. In this study, we selected two contrasting mine waste storage facilities (waste rock from a gold mine and tailings from a molybdenum mine) from the Abitibi region of Quebec (Canada), on which poplars were found to have grown naturally. First, we assessed in situ the impact of vegetation presence on each mine waste type. The presence of balsam poplars improved soil health locally by modifying the physicochemical properties (e.g., higher nutrient content and pH) of the mine wastes and causing an important shift in their bacterial and fungal community compositions, going from lithotrophic communities that dominate mine waste environments to heterotrophic communities involved in nutrient cycling. Next, in a greenhouse experiment we assessed the impact of plant genotype when grown in these mine wastes. Ten genotypes of P. balsamifera were collected locally, found growing either at the mine sites or in the surrounding natural forest. Tree growth was monitored over two growing seasons, after which the effects of genotype-by-environment interactions were assessed by measuring the physicochemical properties of the substrates and the changes in microbial community assembly. Although substrate type was identified as the main driver of rhizosphere microbiome diversity and community structure, a significant effect due to tree genotype was also detected, particularly for bacterial communities. Plant genotype also influenced aboveground tree growth and the physicochemical properties of the substrates. These results highlight the influence of balsam poplar genotype on the soil environment and the potential importance of tree genotype selection in the context of mine waste revegetation.

Universal microbial reworking of dissolved organic matter along environmental gradients

“…DNA was extracted from 250 mg of homogenised soil using the DNeasy PowerSoil Pro kit and the QIAcube® (Qiagen, Germany) automated platform. 16S rRNA and ITS2 libraries were prepared following 64 , except that the first set of PCR reactions were set up by mixing 25 μL of HotStarTaq Plus Master Mix, 19 µL RNase-Free Water (Qiagen, homogenised), 0.5 μL of 10 μM primer and 5 μL of gDNA at 5 ng μL -1 . Indexed and purified amplicons were quantified using the Synergy™ Mx Microplate Reader (BioTek Instruments, USA) before pooling at equimolar concentration.…”

Bioenergy Conversion Potential of Decaying Hardwoods

“…DNA was quantified with the Qubit dsDNA HS Assay Kit on a Qubit 3.0 Fluorometer (Thermo Fisher Scientific, Waltham, MA, USA). Amplicon library preparation for Illumina sequencing of the ITS2 region of the fungal ribosomal DNA was performed as previously described in Rheault, et al [31]. Briefly, the polymerization chain reaction (PCR) is first used to amplify the target fungal DNA, and the success of the PCR is validated by gel electrophoresis.…”

“…A second purification step is then performed before samples are normalized, pooled, and sequenced on an Illumina MiSeq system (Illumina, San Diego, CA, USA). Following DNA sequencing, bioinformatic analysis was carried out in QIIME (version 1.9.1 [32]) as previously described [31] to generate alpha and beta diversity metrics and taxa summary tables. The rarefaction was fixed at 3100 sequences per sample, which allowed us to keep 91 of the 92 samples in the analysis.…”

Distant somatic hybridization alters the structure of wheat root bacterial microbiota

“…Researchers have also demonstrated that the seed‐associated microbial community is affected by factors such as crop, plant genotype, and environmental conditions (Morales Moreira et al., 2021). Apart from affecting the physicochemical properties of substrate, the plant genotype was also found to regulate the rhizosphere fungal and bacterial communities associated with Balsam poplar ( Populus balsamifera L.) (Rheault et al., 2020). Host genotype‐dependent selection of microbial community has been also reported (Morella et al., 2020) and the rhizosphere microbial community profiles have been linked to genotypic characteristics of plants (Lumibao et al., 2020).…”