Oilseed rape cultivation increases the microbial richness and diversity in soils contaminated with cadmium

This investigation aimed to estimate and characterize the microbial diversity in soils with cadmium (Cd) at different concentrations and to evaluate whether Brassica napus can restore the soil microbial diversity. We conducted the pot experiment to analyze the composition of microbial communities in the soil contaminated with 0, 1, and 2 mg/kg Cd, as well as planted with oilseed rape. The bacterial and fungal communities were characterized via next-generation sequencing based on 16S and 18S rRNA gene fragments pyrosequencing, respectively. The results show that cadmium contamination decreased both the microbial richness and diversity in the soil, while the cultivation of oilseed rape increased the richness and diversity. In bacteria, Proteobacteria was the most abundant phylum in all the samples accounting for 39.62 to 46.14%, followed by Bacteroidetes, Actinobacteria, and Chloroflexi. These phyla collectively comprised more than 70% of all phyla. Ascomycota was the most abundant phylum in all samples in fungi (89.65 to 96.00%), and it was the only phylum whose abundance was increased with the rise of Cd concentration. Microbial richness and diversity were affected by the combined action of Cd and B. napus. Cd contamination decreased the microbial richness and diversity, while cropping with oilseed rape increased the microbial richness and diversity, which alleviated the deleterious effect of the Cd pollution in soils. These reflected that oilseed rape played a positive role in maintaining species diversity of microorganism from the side

Editing of a Novel Cd Uptake-Related Gene CUP1 Contributes to Reducing Cd Accumulations in Arabidopsis thaliana and Brassica napus

Brassica napus is a Cd hyperaccumulator, which is a serious threat to food and fodder safety. However, no related studies on developing Cd-safe B. napus have been reported yet. Here, we screened out a novel Cd uptake-related gene, AtCUP1, from the major facilitator superfamily in Arabidopsis thaliana. The mutation of AtCUP1 decreased Cd accumulation, both in roots and shoots of A. thaliana. Furthermore, the disruption of the AtCUP1 gene by the CRISPR/Cas9 system significantly reduced Cd accumulation in A. thaliana. Interestingly, the disruption of the BnCUP1 gene, an orthologous gene of AtCUP1, by the CRISPR/Cas9 system also diminished Cd accumulation in both roots and shoots of B. napus based on the hydroponics assay. Furthermore, for the field experiment, the Cd accumulations of BnCUP1-edited lines were reduced by 52% in roots and 77% in shoots compared to that of wild-type (WT) lines, and the biomass and yield of BnCUP1-edited lines increased by 42% and 47% of that of WT, respectively. Noteworthily, agronomic characteristics of B. napus were not apparently affected by BnCUP1-editing. Thus, BnCUP1-edited lines are excellent non-transgenic germplasm resources for reducing Cd accumulation without a distinct compromise in yield, which could be applied to agricultural production in Cd-contaminated soils

Metagenomic analysis of microbial community and function involved in cd-contaminated soil

Background: Soil contaminated with the heavy metal Cadmium (Cd) is a widespread problem in many parts of the world. Based on metagenomic analysis, we investigated the functional potential and structural diversity of the microbial community in Cd-contaminated and non-contaminated soil samples and we explored the associated metabolic pathway network in cluster of orthologous groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Results: The results showed that microorganisms in these soils were quite abundant, and many of them possessed numerous physiological functions. However, Cd-contamination has the potential to reduce the microbial diversity and further alter the community structure in the soil. Notably, function analysis of the crucial microorganisms (e.g. Proteobacteria, Sulfuricella and Thiobacillus) indicated that these bacteria and their corresponding physiological functions were important for the community to cope with Cd pollution. The COG annotation demonstrated that the predominant category was the microbial metabolism cluster in both soil samples, while the relative abundance of metabolic genes was increased in the Cd-contaminated soil. The KEGG annotation results exhibited that the non-contaminated soil had more genes, pathways, modules, orthologies and enzymes involved in metabolic pathways of microbial communities than the Cd-contaminated soil. The relative abundance of some dominant KEGG pathways increased in the Cd contaminated soil, and they were mostly enriched to the metabolism, biosynthesis and degradation of amino acids, fatty acids and nucleotides, which was related to Cd tolerance of the microorganisms. Conclusions: Cd-contamination can decrease the taxonomic species of microbes in soil and change the soil microbial composition. The functional pathways involved in the soil change with microbial structure variation, many of which are related to the heavy metal tolerance of soil microbes. The Cd-contaminated soil microbes is a potential resource for exploring cadmium resistant or tolerant bacteria

Additional file 1: of Metagenomic analysis of microbial community and function involved in cd-contaminated soil

Definition of the KEGG pathways in the two soil samples. (DOCX 22 kb

A protein-independent fluorescent RNA aptamer reporter system for plant genetic engineering

Fluorescent RNA aptamers could potentially be used as protein-independent reporters of transgene expression in plants. Here, the authors report that an optimized RNA aptamer, developed from Broccoli, can be used to detect transgene expression in stable and transiently transformed plant tissue