Benomyl modulates paracetamol bioaccumulation and endophytic microbiome diversity in zucchini

Paracetamol, a widely used analgesic and antipyretic, has emerged as a prevalent environmental pollutant that poses risks to various organisms, including plants. Phytoremediation, particularly the use of Cucurbitaceae family plants, offers a promising, eco-friendly approach to mitigate such pollutants. This study investigated the bioaccumulation of paracetamol in zucchini (Cucurbita pepo cv. Atena Polka) and explored the role of the fungicide benomyl in modulating paracetamol bioaccumulation. Additionally, the impacts of these compounds on zucchini health (measured by biomass, chlorophyll content, and phenolic compound concentrations) and on the diversity of the endophytic microbiome (assessed via the Biolog EcoPlate™ and identification of isolated endophytes via 16S rRNA gene sequencing) were evaluated. Four treatments were assessed over a 28-day cultivation period: control (no pharmaceutical or fungicide), paracetamol (25 mg/kg) (P), paracetamol + benomyl (P + B), and benomyl alone (B). The results revealed that paracetamol accumulated significantly more in the roots of the P variant, but notably, the P + B variant presented a 24-fold increase in paracetamol concentration in aboveground tissues compared with the P variant. The bioaccumulation factors indicated that benomyl significantly enhanced the translocation of paracetamol to aerial parts in the P + B variant. Compared with the control, all the treatments reduced plant biomass, with the lowest values observed in the P variant. The chlorophyll content, in turn, was the highest in the P + B treatment, suggesting that benomyl helped mitigate oxidative stress. The levels of phenolic compounds, particularly flavonoids and phenylpropanoids, were elevated in the P variant, indicating a stress response. Additionally, the endophytic microbial community showed diminished diversity in the P variant. In the P + B variant, in turn, the microbial diversity measured via Biolog Ecoplates and 16S rRNA gene sequencing was greater. Our findings demonstrate that benomyl significantly enhanced the accumulation of paracetamol in the aerial parts of zucchini while promoting the resilience of plants and their associated endophytic bacteria and improving their potential for the phytoremoval of pharmaceutical pollutants.