Enantioselective Biotransformation of Chiral PCBs in Whole Poplar Plants

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Peer Reviewed


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Environmental science & technology

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Chiral PCBs have been used as molecular probes of biological metabolic processes due to their special physical, chemical, and biological properties. Many animal studies showed the enantioselective biotransformation of chiral PCBs, but it is unclear whether plants can enantioselectively biotransform chiral PCBs. In order to explore the enantioselectivity of chiral PCBs in whole plants, poplars (Populus deltoides nigra, DN34), a model plant with complete genomic sequence, were hydroponically exposed to 2,20 ,3,50 ,6-pentachlorobiphenyl (PCB95) and 2,20 ,3,30 ,6,60 -hexachlorobiphenyl (PCB136) for 20 days. PCB95 and PCB136 were shown to be absorbed, taken-up and translocated in whole poplars, and they were detected in various tissues of whole poplars. However, the enantioselectivity of poplar for PCB95 and PCB136 proved to be quite different. The first eluting enantiomer of PCB95 was enantioselectively removed in whole poplar, especially in the middle and bottom xylem. It was likely enantioselectively metabolized inside poplar tissues, in contrast to racemic mixtures of PCB95 remaining in hydroponic solutions in contact with plant roots of whole and dead poplars. Unlike PCB95, PCB136 remained nearly racemic in most parts of whole poplars after 20 days exposure. These results suggest that PCB136 is more difficult to be enantioslectively biotransformed than PCB95 in whole poplars. This is the first evidence of enantioselectivity of chiral PCBs in whole plants, and suggests that poplars can enantioselectively biotransform at least one chiral PCB.


This work was supported by the Iowa Superfund Basic Research Program (SBRP), National Institute of Environmental Health Science, Grant Number P42ES013661. We thank Collin Just, Civil and Environmental Engineering, University of Iowa, for supporting this experiment and also the Center for Global and Regional Environmental Research (CGRER) for financial support. This paper is a contribution from the W. M. Keck Phytotechnology Laboratory at the University of Iowa.

Three figures, including the experiment setup, background signals of blank poplar tissues at the retention times of PCB95 and PCB136 on GC-ECD, some selected typical chromatograms of PCB95, are shown. Two tables contain the data of PCB136 and metabolic mechanisms of chiral PCBs in animals potentially applicable to poplars. This material is available free of charge via the Internet at es1033662_si_001.pdf (439.33 kb)

Published Article/Book Citation

Environmental science & technology, 45:6 (2011) pp.2308-2316.

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