Identifying the Specific Root Microbiome of the Hyperaccumulator Noccaea brachypetala Growing in Non-metalliferous Soils

Abstract

Noccaea brachypetala is a close relative of Noccaea caerulescens, a model plant species used in metal hyperaccumulation studies. In a previous survey in the Catalan Pyrenees, we found two occidental and two oriental N. brachypetala populations growing on non-metalliferous soils, with accumulated high concentrations of Cd and Zn. Our hypothesis was that the microbiome companion of the plant roots may influence the ability of these plants to absorb metals. We performed high-throughput sequencing of the bacterial and fungal communities in the rhizosphere soil and rhizoplane fractions. The rhizobiomes and shoot ionomes of N. brachypetala plants were analyzed along with those from other non-hyperaccumulator Brassicaceae species found at the same sampling locations. The analyses revealed that microbiome richness and relative abundance tended to increase in N. brachypetala plants compared to non-hyperaccumulator species, regardless of plant location. We confirmed that the root compartment is a key factor in describing the community composition linked to the cohabiting Brassicaceae species, and the rhizoplane fraction contained the specific and rare taxa associated with each species. N. brachypetala plants harbored a similar relative abundance of fungi compared to the other plant hosts, but there was a notable reduction in some specific taxa. Additionally, we observed an enrichment in the hyperaccumulator rhizoplane of previously described metal-tolerant bacteria and bacteria involved in nitrogen cycling. The bacteria involved in the nitrogen cycle could contribute indirectly to the hyperaccumulator phenotype by improving soil quality and fertility. Our results indicate that N. brachypetala captures a particular prokaryotic community from the soil. This particular prokaryotic community may benefit the extraction of metal ions and/or improve plant nutrition. Our research identified satellite groups associated with the root niche of a hyperaccumulator plant that may assist in improving biological strategies in heavy metal remediation.

Molybdenum Trioxide Nanoparticles as Promising Stimulators for Facilitating Phytoremediation by Cd Hyperaccumulator Solanum nigrum L

“…For the shoots of S. nigrum, the increasing levels of Mo stimulated Cd accumulation for both MoO 3 NPs and Mo 6+ treatments, where the highest Cd concentration was observed at 34.06 ± 6.88 mg kg −1 in the NP-40 group, followed by 29.06 ± 4.98 mg kg −1 in the I-40 group compared to CK (11.96 ± 2.30 mg kg −1 ), while for the plant roots, Cd concentrations (7.10 ± 0.47 mg kg −1 in CK) climbed to 36.89 ± 4.59 and 32.28 Nevertheless, excessive Mo amendment jeopardized the homeostasis of heavy-metal translocation and normal functioning in vascular systems, which contribute to excessive accumulation of nonessential elements (as indicated by the Cd, As, and Pb contents displayed in Table S3) in S. nigrum shoots for the NP/I-40 groups compared to CK (p < 0.05). 50 Similar to plant growth, MoO 3 NPs also exhibited stronger stimulation in Cd uptake of S. nigrum than that exhibited by ion treatment under the same dose.…”

“…In the present study, we observed that the application of micronutrient Mo materials significantly stimulated Cd uptake by the root tissue of S. nigrum , and the transport of Cd to the above-ground part was to avoid root damage by excessive Cd accumulation. Nevertheless, excessive Mo amendment jeopardized the homeostasis of heavy-metal translocation and normal functioning in vascular systems, which contribute to excessive accumulation of nonessential elements (as indicated by the Cd, As, and Pb contents displayed in Table S3) in S. nigrum shoots for the NP/I-40 groups compared to CK ( p < 0.05) . Similar to plant growth, MoO 3 NPs also exhibited stronger stimulation in Cd uptake of S. nigrum than that exhibited by ion treatment under the same dose.…”

Metaphors as design tools for microbial consortia: An analysis of recent peer‐reviewed literature

“…It is also occasionally explicit in, e.g., studies of root‐associated microbiota (e.g. Martos et al., 2021 ). At least as understood in social sciences, this frame does not necessarily stem from an ecological framework or rest on ecological assumptions.…”