Fungicide-mediated modulation of dieldrin uptake in zucchini: effects on pollutant reduction, plant physiology, and endophytic microbiome

The contamination of agricultural soils with organochlorine pesticides (OCPs), such as dieldrin, poses significant risks to consumer health worldwide. This issue is particularly significant in crops like zucchini (Cucurbita pepo), which effectively accumulate hydrophobic organic pollutants. There is hence a pressing need to develop strategies to reduce OCP uptake in cucurbits. This study evaluated the efficacy of two fungicides, Benomyl (Be) and Daconil (Da), in reducing dieldrin (Di) accumulation in Cucurbita pepo cv. Atena Polka. Di concentrations were measured in soil and plant tissues, and bioconcentration factors (BCFs) were calculated to assess soil to plant pollutant transfer. It also assessed the effects of Di, and Di with Be or Da on plant health and endomicrobiome functional diversity. The applied fungicides significantly lowering pollutant levels in the crop. Initial soil Di level was 12.5 μg/kg, decreasing to 7.88 μg/kg after incubation. However, fungicide treatments resulted in higher residual Di levels in soil: 10.65 μg/kg for Di + Be and 8.68 μg/kg for Di + Da. Conversely, Di accumulation fell in the aboveground plant tissues, with Be reducing accumulation by 31 % and Da by 13 %. The role of major latex-like proteins (MLPs) in dieldrin binding and transport was also examined. Recombinant CpMLP-AP1 from Atena Polka showed strong dieldrin-binding affinity, confirming the important role of MLPs in OCP uptake. The fungicide treatments were found to improve physiological parameters, insofar that they reduced lipid peroxidation and oxidative stress markers, and increased chlorophyll content and biomass. They also influenced the functional diversity of endophytic microbiota, indicating a broader impact on plant-microbe interactions. This study proposes promising strategies for reducing OCP contamination in cucurbits, improving food safety and crop production, while advancing our understanding of molecular and ecological mechanisms in pollutant management.