Structure-selective accumulation of polychlorinated biphenyls in Cucurbita pepo

Nine zucchini cultivars (Cucurbita pepo subspecies ovifera and pepo) were grown in soil containing a mixture of dioxins and dioxin-like compounds. Plants of subspecies pepo accumulated polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in their aerial parts at higher concentrations than did plants of subspecies ovifera. In all cultivars, the accumulation of PCDDs and PCDFs in the aerial parts decreased with increasing hydrophobicity, whereas for PCBs, a negative correlation was observed in only two cultivars. The other seven cultivars selectively accumulated ortho-chlorinated biphenyls. Our results contribute to the understanding of the mechanisms underlying these phenomena, which should help in the development of efficient methods for phytoremediation of hydrophobic contaminants. (C) Pesticide Science Society of Japan