The zucchini (Cucurbita pepo) cultivars 'Patty Green', 'Black Beauty', and 'Gold Rush' were cultivated on weathered dioxin-contaminated soil in pots, and concentrations of the 29 dioxin-like compounds that were assigned WHO-TEFs, three non-toxic polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), and two non-dioxin-like polychlorinated biphenyls (PCBs) were analyzed. Toxic equivalent (TEQ) values accumulated in 'Black Beauty' and 'Gold Rush' were about 180 times higher than those in 'Patty Green'. The bioconcentration factor (BCF) based on total mass concentration of the twelve dioxin-like PCBs was higher than those of the seven PCDDs and ten PCDFs in all the cultivars. The BCFs for PCDD and PCDF congeners were negatively correlated with octanol-water partition coefficients in all the plants. No correlations were observed in PCB congeners in the high accumulators, although in 'Patty Green' the BCFs for PCB congeners were significantly correlated with octanol-water partition coefficients. Our findings suggest that the high accumulators had unknown, unique mechanisms for uptake of PCBs, whereas PCDDs and PCDFs were absorbed based on their physicochemical properties.

No abstract

Chimeric repressor gene-silencing technology is a useful tool for changing morphology of ornamental plants. It has previously been demonstrated that the chimeric repressor TCP3SRDX, which consists of Arabidopsis TCP3 and an ERF-associated amphiphilic repression motif repression domain, perturbs the marginal morphology of Arabidopsis leaves and flowers. To obtain new rose cultivars that have ornamental values, we attempted to alter the morphology of Rosaϫ hybrida cv. Lavande with TCP3SRDX. The TCP3SRDX transgenic rose plants showed interesting phenotypes: the number of leaflets and the size of leaf teeth increased, the petals were wavy, and the sepals were compound-leafy. We succeeded in altering rose morphology using Arabidopsis TCP3 without the sequence information of a TCP3 homologue in the target plant species.

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.