Physiology combined with metabolomics reveal selenium acting as a mitigator for Perilla frutescens (L.) Britt. growth under oxytetracycline condition: by regulating photosynthesis, redox homeostasis and secondary metabolites.

The accumulation of antibiotics in soil threatens agricultural ecosystems and human health. Oxytetracycline (OTC), a plant-absorbable antibiotic, generally exerts inhibitory effects on plant growth. Selenium (Se) plays a crucial role in safeguarding plants resistant to a variety of abiotic stresses. However, the potential of Se to mitigate the toxic influences of antibiotics on plants remains unreported in the literature. This paper integrates physiology and metabolomics to study the effects of OTC (150 mg kg) alone and OTC combined with Se (1, 15, and 40 mg L) on the growth, quality and metabolites of perilla. OTC led to a reduction in total chlorophyll content (8.3 %), shoot and root biomass (19.9 and 12.8 %) of perilla. The 1 mg L Se combined with OTC treatment alleviated OTC damage on perilla by improving phenotype and photosynthesis (plant height: 11.0 %, total chlorophyll content: 9.9 %), and plant height and pigment content reached the level of the control. However, the 40 mg L Se combined with OTC treatment exacerbated the toxicity of perilla by inhibiting photosynthesis (chlorophyll a and b contents: 13.6 and 6.6 %) and antioxidant enzyme activity (SOD: 5.6 %). Metabolomics analysis revealed that when treated with OTC alone, the upregulation of adonixanthin indicated that OTC stimulated the antioxidant defense system of perilla. The results showed that OTC inhibited the growth of perilla by reducing photosynthesis and the content of active ingredients. 1 mg L Se can alleviate the inhibitory effect of OTC on the growth of perilla by improving photosynthesis and the content of secondary metabolites.