Can the agrochemical Oryzemate treatment control the uptake of pyrene by Cucurbita pepo through the regulation of major latex-like proteins?

Abstract

Members of the Cucurbitaceae family accumulate several hydrophobic organic pollutants in their above-ground parts at high concentrations. Major latex-like proteins (MLPs) identified in Cucurbita pepo bind to hydrophobic organic pollutants, such as pyrene and dieldrin, in roots, forming complexes that are transported via xylem vessels to the above-ground plant parts. However, soil remediation of hydrophobic organic pollutants utilizing MLPs has not been established. In this study, the uptake of the hydrophobic organic pollutant pyrene by C. pepo was promoted through the upregulation of the expression of MLP genes following agrochemical treatment. Probenazole, an active ingredient in the agrochemical Oryzemate, was previously found to upregulate the promoter activity of MLP genes in the roots of transgenic tobacco plants. Here, Oryzemate treatment increased the levels of MLPs in the roots and xylem sap of C. pepo. Oryzemate treatment slightly increased and significantly decreased the pyrene concentration in the xylem sap of C. pepo cultivated in high- and low-contamination soils, respectively. Probenazole competitively inhibited the binding of MLPs to pyrene in vitro, thereby likely suppressing its uptake by C. pepo in low-contamination soil. This study demonstrated that Oryzemate possesses dual effects: effective phytoremediation and safe crop production, depending on the soil contamination level.