Subspecies-Level Variation in the Phytoextraction of Weathered p,p‘-DDE by Cucurbita pepo

Abstract

Previous studies indicate that Cucurbita pepo can phytoextract highly weathered persistent organic pollutants (POPs) from soil and translocate large quantities to aerial tissues. To investigate intraspecific variability in uptake potential, a field study was conducted to quantify the phytoextraction of weathered p,p'-DDE by 21 cultivar varieties of summer squash from two distinct subspecies, C. pepo ssp texana and C. pepo ssp pepo. Significant differences exist between the two subspecies, with average root and stem to soil bioconcentration factors (BCF, dry weight ratio of contaminant concentration in the vegetation to that in the soil) of 7.22 and 5.40 for ssp pepo and of 2.37 and 0.454 for spp texana, respectively. The amounts of weathered p,p-DDE extracted from the soil by ssp pepo and ssp texana were 0.301 and 0.065%, respectively, with maximum values within each subspecies of 0.780 and 0.182%, respectively. The quantities of 14 inorganic elements were determined in both the soil and tissues (roots, stems, leaves, and fruit) of all 21 cultivar varieties. Phosphorus concentrations in the tissues of ssp pepo were 14 (fruit)-73% (stems) greater than those of ssp texana. These data support our hypothesis that the unique ability of certain cultivars of C. pepo to phytoextract highly weathered POPs from soil is the result of low molecular weight organic acid exudation as a unique phosphorus acquisition mechanism.

Structure-selective accumulation of polychlorinated biphenyls in Cucurbita pepo

“…Moreover, subspecies-level variation in phytoextraction of DDE by C. pepo has been reported. 10) Structure-selective accumulation has also been observed for chlordane 11) and dioxins and dioxin-like compounds.…”

Concomitant uptake of antimicrobials and Salmonella in soil and into lettuce following wastewater irrigation

“…This suggests that root exudates and endophyte population may be the dominant mechanisms affecting the variation in uptake between the two cultivars of lettuce. Organic acid exudates has been shown to play a key role in persistent organic contaminant uptake in 21 cultivars of squash from soil (White et al, 2003b) and differences in exudates between cultivars has also been demonstrated in rice (Aulakh et al, 2001). The mechanisms responsible for cultivar-specific differences in antimicrobial uptake in lettuce merits additional research.…”

A Major Latex-Like Protein Is a Key Factor in Crop Contamination by Persistent Organic Pollutants

“…2B). The band intensities and the BCFs of PCDDs and PCDFs and phytoextraction of p,p9-DDE were also significantly positively correlated (White et al, 2003;Matsuo et al, 2011; r = 0.711 for PCDDs, r = 0.742 for PCDFs, and r = 0.780 for p,p9-DDE, P , 0.05 in all cases; Supplemental Fig. S2).…”

“…Previous studies reported that members of the Cucurbitaceae family, particularly C. pepo, which includes pumpkin and zucchini, accumulated higher levels of PCDDs and PCDFs (Hülster et al, 1994;Inui et al, 2008), 2,2-bis(p-chlorophenyl) 1,1-dichloroethylene (p,p9-DDE; White et al, 2003), PCBs (Aslund et al, 2008;Inui et al, 2008), chlordane (Mattina et al, 2004), and drins (Otani et al, 2007) compared with the levels in other plant species. Thus, it appears that the Cucurbitaceae family has unique mechanisms of POP uptake and translocation.…”