Cadmium Exposure-Sedum alfredii Planting Interactions Shape the Bacterial Community in the Hyperaccumulator Plant Rhizosphere

Abstract

Rhizospheric bacteria play important roles in plant tolerance and activation of heavy metals. Understanding the bacterial rhizobiome of hyperaccumulators may contribute to the development of optimized phytoextraction for metal-polluted soils. We used 16S rRNA gene amplicon sequencing to investigate the rhizospheric bacterial communities of the cadmium (Cd) hyperaccumulating ecotype (HE) in comparison to its nonhyperaccumulating ecotype (NHE). Both planting of two ecotypes of and elevated Cd levels significantly decreased bacterial alpha-diversity and altered bacterial community structure in soils. The HE rhizosphere harbored a unique bacterial community differing from those in its bulk soil and NHE counterparts. Several key taxa from ,, and TM7 were especially abundant in HE rhizospheres under high Cd stress. The actinobacterial genus was responsible for the majority of the divergence of bacterial community composition between the HE rhizosphere and other soil samples. In the HE rhizosphere, the abundance of was 3.31- to 16.45-fold higher than that in other samples under high Cd stress. These results suggested that both the presence of the hyperaccumulator and Cd exposure select for a specialized rhizosphere bacterial community during phytoextraction of Cd-contaminated soils and that key taxa, such as the species affiliated with the genus, may play an important role in metal hyperaccumulation. is a well-known Cd hyperaccumulator native to China. Its potential for extracting Cd relies not only on its powerful uptake, translocation, and tolerance for Cd but also on processes underground (especially rhizosphere microbes) that facilitate root uptake and tolerance of the metal. In this study, a high-throughput sequencing approach was applied to gain insight into the soil-plant-microbe interactions that may influence Cd accumulation in the hyperaccumulator Here, we report the investigation of rhizosphere bacterial communities of in phytoremediation of different levels of Cd contamination in soils. Moreover, some key taxa in its rhizosphere identified in the study, such as the species affiliated with genus , may shed new light on the involvement of bacteria in phytoextraction of contaminated soils and provide new materials for phytoremediation optimization.

New Data Set of Polychlorinated Dibenzo-p-dioxin and Dibenzofuran Half-Lives: Natural Attenuation and Rhizoremediation Using Several Common Plant Species in a Weathered Contaminated Soil

“…In fact, all the treatments apart from P8 and P9 showed a significantly lower richness value compared to their correspondent unplanted control. This result, in agreement with previous studies, 50 seems to reflect a prolonged selective pressure exerted by the plants on the bacterial populations in the rhizosphere, which was of course absent in the nonplanted controls. Taken together, the analyzed α-diversity indices indicated that the microbial communities associated with P1 ( P. arundinacea ) and P3 ( F. arundinacea ) were the most impacted by the applied treatment and showed the higher number of significantly different indices compared to the related unplanted control (C2).…”

Characterization and comparison of the bacterial communities of rhizosphere and bulk soils from cadmium-polluted wheat fields

“…For example, the inoculation of Pseudomonas aeruginosa and Burkholderia gladioli enhanced Cd tolerance in the seedlings of Lycopersicon esculentum ( Khanna et al, 2019 ). Moreover, many reports have shown that bacterial-community structure and diversity respond to direct heavy-metal contamination in soil ( Abdu, Abdullahi & Abdulkadir, 2017 ; Luo et al, 2018 ; Hou et al, 2018 ). For example, the bacterial community of soils contaminated with Pb, Zn, and Cr significantly differ, with Zn decreasing both diversity and species richness at the species and family levels, while plant-species richness was not correlated with bacterial diversity ( Golebiewski et al, 2014 ).…”

The Effects of Different Lead Pollution Levels on Soil Microbial Quantities and Metabolic Function with/without Salix integra Thunb. Planting

“…Zhu et al [48] also suggested heavy metal contamination could play a more important role in shaping bacterial diversity. The bacterial growth rate and biomass in soils was found to consistently diminish along the Cd gradient, regardless of planting Sedum alfredii [49]. Similarly, Golebiewski et al [50] found that species richness, diversity, and bacterial communities in soils with low levels of Pb contamination were higher than in highly polluted soils.…”