Novel Insights into Uptake, Translocation, and Transformation Mechanisms of 2,2′,4,4′-Tetra Brominated Diphenyl Ether (BDE-47) in Wheat (Triticum aestivum L.): Implication by Compound-Specific Stable Isotope and Transcriptome Analysis

Abstract

The uptake, translocation, and transformation of 2,2′,4,4′-tetra brominated diphenyl ether (BDE-47) in wheat (Triticum aestivum L.) were comprehensively investigated by hydroponic experiments using compound-specific stable isotope analysis (CSIA) and transcriptome analysis. The results indicated that BDE-47 was quickly adsorbed on epidermis of wheat roots and then absorbed in roots via water and anion channels as well as an active process dependent on energy. A small fraction of BDE-47 in roots was subjected to translocation acropetally, and an increase of δ 13 C values in shoots than roots implied that BDE-47 in roots had to cross at least one lipid bilayer to enter the vascular bundle via transporters. In addition, accompanied by the decreasing concentrations, δ 13 C values of BDE-47 showed the increasing trend with time in shoots, indicating occurrence of BDE-47 transformation. OH-PBDEs were detected as transformation products, and the hydroxyl group preferentially substituted at the ortho-positions of BDE-47. Based on transcriptome analysis, genes encoding polybrominated diphenyl ether (PBDE)-metabolizing enzymes, including cytochrome P450 enzymes, nitrate reductases, and glutathione S-transferases, were significantly upregulated after exposure to BDE-47 in shoots, further evidencing BDE-47 transformation. This study first reported the stable carbon isotope fractionation of PBDEs during translocation and transformation in plants, and application of CSIA and transcriptome analysis allowed systematically characterize the environmental behaviors of pollutants in plants.

Phloem Redistribution of Pesticide Phenamacril in Plants Followed by Extensive Biotransformation

“…For the seven genes, the transcriptome analysis results were also validated by qRT-PCR; for example, TraesCS7A03G0966600 encoding CYP450 in phenamacril treated roots was expressed by 3.0 times greater than that in untreated roots after 4 days of exposure (Figure S31). Higher activities of metabolic enzymes could be the key factors in modulating the transformation of phenamacril in plants …”

“…Higher activities of metabolic enzymes could be the key factors in modulating the transformation of phenamacril in plants. 45 Estimation of Environmental Persistence and Toxicity of Phenamacril and Its Metabolites. The prediction models were applied to evaluate the lipophilicity, environmental persistence, and toxicity of phenamacril and its metabolites.…”